Phenols, Volatile Compounds from Vegetables, Medicinal and Aromatic Plants

foods

Review Bioactive (Poly)phenols, Volatile Compounds from Vegetables, Medicinal and Aromatic Plants

Teresa Pinto 1,*,† , Alfredo Aires 2,† , Fernanda Cosme 3 , Eunice Bacelar 1 , Maria Cristina Morais 2, Ivo Oliveira 1, Jorge Ferreira-Cardoso 1 , Rosário Anjos 1 , Alice Vilela 3 and Berta Gonçalves 1

1 CITAB, Centre for the Research and Technology of Agro-Environmental and Biological Sciences, Department of Biology and Environment, School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, P-5000-801 Vila Real, Portugal; [email protected] (E.B.); [email protected] (I.O.); [email protected] (J.F.-C.); [email protected] (R.A.); [email protected] (B.G.) 2 CITAB, Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás-os-Montes and Alto Douro, P-5000-801 Vila Real, Portugal; [email protected] (A.A.); [email protected] (M.C.M.) 3 CQ-VR, Chemistry Research Centre, Department of Biology and Environment, School of Life Sciences and Environment, University of Trás-os-Montes and Alto Douro, P-5000-801 Vila Real, Portugal; [email protected] (F.C.); [email protected] (A.V.) * Correspondence: [email protected]; Tel.: +351-259-350-345 † Contributed equally to this work.

Abstract: Polyphenols, as well as volatile compounds responsible for aromatic features, play a critical role in the quality of vegetables and medicinal, and aromatic plants (MAPs). The research conducted in recent years has shown that these plants contain biologically active compounds, mainly polyphenols, that relate to the prevention of inﬂammatory processes, neurodegenerative diseases, cancers, and cardiovascular disorders as well as to antimicrobial, antioxidant, and antiparasitic properties. Throughout the years, many researchers have deeply studied polyphenols and volatile

Citation: Pinto, T.; Aires, A.; compounds in medicinal and aromatic plants, particularly those associated with consumer’s choices Cosme, F.; Bacelar, E.; Morais, M.C.; or with their beneﬁcial properties. In this context, the purpose of this review is to provide an overview Oliveira, I.; Ferreira-Cardoso, J.; of the presence of volatile and nonvolatile compounds in some of the most economically relevant and Anjos, R.; Vilela, A.; Gonçalves, B. consumed vegetables and medicinal and aromatic plants, with an emphasis on bioactive polyphenols, Bioactive (Poly)phenols, Volatile polyphenols as prebiotics, and, also, the most important factors that affect the contents and proﬁles Compounds from Vegetables, of the volatile and nonvolatile compounds responsible for the aromatic features of vegetables and Medicinal and Aromatic Plants. Foods MAPs. Additionally, the new challenges for science in terms of improving polyphenol composition 2021, 10, 106. https://doi.org/ and intensifying volatile compounds responsible for the positive characteristics of vegetables and 10.3390/foods10010106 medicinal and aromatic plants are reported.

Received: 3 December 2020 Keywords: aromatic plants; bioactive compounds; consumers; medicinal plants; phenolic com- Accepted: 1 January 2021 Published: 6 January 2021 pounds; plant breeders; volatile compounds; vegetables

Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- 1. Introduction nal affiliations. The concept of “quality” is wide, but in horticulture, it can be defined as the degree of excellence given by the combination of different attributes or characteristics that give each product value in terms of its proposed use [1]. In this concept, visual appearance, ability to endure postharvest processing operations, chemical and nutritional composition, and Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. aroma can be included [2]. Advances have been made in horticultural breeding, and now This article is an open access article it is possible to find fruits and vegetables with characteristics that growers and retailers distributed under the terms and con- desire, such as high yield, high resistance to pest attacks and disease, attractive appearance, ditions of the Creative Commons At- and capacity to support different handling and processing operations. However, most tribution (CC BY) license (https:// of the time, many of these horticultural crops fail to achieve top nutritional and flavour creativecommons.org/licenses/by/ characteristics [3]. Increasing horticultural crops’ flavour by breeding is still not an easy 4.0/).

Foods 2021, 10, 106. https://doi.org/10.3390/foods10010106 https://www.mdpi.com/journal/foods Foods 2021, 10, 106 2 of 29

task, due to the multitude of factors that affect the synthesis of volatile and nonvolatile compounds responsible for flavour attributes such as climate, cultural practices, agricultural practices (organic vs. conventional), and pre- and postharvest processing operations [4]. Additionally, the astringency, dryness, viscosity, heat, coolness, prickling, and pain, often referred to as the “texture” of foods, can affect the flavour of vegetables and medicinal and aromatic plants (MAPs) [5]. This review presents a discussion of the most important factors that affect the contents and profiles of the volatile and nonvolatile compounds responsible for the aromatic features of vegetables and MAPs, as well as the recent advances in plant breeding regarding the achievement of chemical compounds responsible for the typical aromatic features’ sensory attributes.

2. Plant Bioactive Phenolic Compounds Vegetables and MAPs are important sources of bioactive phenolic compounds and have a key role in the development of compounds eliciting beneficial health effects [6]. Phenolic bioactive compounds of plant origin are those secondary metabolites possessing desired health benefit effects [7]. They might be produced from two distinct pathways: (i) shikimic acid (phenylpropanoids) and (ii) acetic acid (phenols) [8]. Due to their abundance in vegetables and MAPs, the study of phenolic compounds’ (simple phenolics, coumarins, lignans, flavonoids, isoflavonoids, anthocyanins, proanthocyanidins, and stilbenes) effects on health has increased in recent years, due to the growing evidence indicating that polyphenols are a major class of bioactive phytochemicals. Their consumption may play a role in the prevention of several chronic diseases as potent antioxidant properties, prevention of diseases induced by oxidative stress, and prevention of some specific cardiovascular (mainly high cholesterol levels, high blood pressure) and neurodegenerative diseases (such as Alzheimer’s or Parkinson’s, type II diabetes, cancers, urinary tract infections) [9–13]. However, the health effects of phenolic compounds are dependent on their type, quantity consumed, as well as on their bioavailability. The amount of total phenolic compounds is greater in dark vegetables, such as red kidney beans, black beans (Phaseolus vulgaris), and black gram (Vigna mango). Bravo [9] determined (by regarding dry matter, mg/100 g) the amount of total phenolic compounds in several vegetables such as black gram (540–1200), chickpeas (78–230), cowpea (175–590), common beans (34–280), green gram (440–800), pigeon peas (380–1710), Brussel sprouts (6–15), cabbage (25), leek (20–40), onion (100–2025), parsley (55–180), and celery (94). Phenolic acids have been recently widely studied because of their potential protective roles. Phenolic acids have a benzene ring, a carboxylic group, and one or more hydroxyl and/or methoxyl groups. They are usually divided into benzoic acid derivatives (i.e., hydroxybenzoic acids, C6-C1) (Figure1a) and cinnamic acid derivatives (i.e., hydroxycinnamic acids, C6-C3) (Figure1b), based on the constitutive carbon structures. The amount

of hydroxybenzoic acid (C6-C1 derivatives) (e.g., gallic acid, salicylic acid, salicylaldehyde, and protocatechuic acid) is typically low in edible plants [14]. Phenolic acids may make up about one-third of the phenolic compounds in the human diet; these substances have a powerful antioxidant activity that may help protect the body from free radicals [9,15].

(a) (b)

FigureFigure 1. Chemical 1. Chemicalstructures of hydroxy structuresbenzoic acids (a) of and hydroxybenzoic hydroxycinnamic acids (b). acids (a) and hydroxycinnamic acids (b).

According to Khadem and Marles [16], gallic acid has antineoplastic and bacteriostatic activities, and salicylic acid exerts anti-inflammatory, analgesic, antipyretic, antifungal, and antiseptic properties. Protocatechuic acid has also been described as having several bioac-

Foods 2021, 10, x FOR PEER REVIEW 3 of 28

According to Khadem and Marles [16], gallic acid has antineoplastic and bacterio- Foods 2021, 10, 106 static activities, and salicylic acid exerts anti-inflammatory, analgesic, antipyretic, antifun-3 of 29 gal, and antiseptic properties. Protocatechuic acid has also been described as having several bioactivities such as anti-inflammatory, antifungal, and antioxidant ones [17]. For instance, p-hydroxybenzoic acid has been isolated from many sources including carrots tivities such as anti-inflammatory, antifungal, and antioxidant ones [17]. For instance, p- (Daucus carota) [18] and protocatechuic acid from onion, garlic, and relatives (Allium spp.) hydroxybenzoic acid has been isolated from many sources including carrots (Daucus carota) [19]. [18] and protocatechuic acid from onion, garlic, and relatives (Allium spp.) [19]. The hydroxycinnamic acids (C6-C3 derivatives) are more abundant than the hy- The hydroxycinnamic acids (C -C derivatives) are more abundant than the hydrox- droxybenzoic acids. The four most common6 3 hydroxycinnamic acids are ferulic acid, caf- ybenzoic acids. The four most common hydroxycinnamic acids are ferulic acid, caffeic feic acid, coumaric acid, and sinapic acid. These acids are frequently present in plants in acid, coumaric acid, and sinapic acid. These acids are frequently present in plants in the the combined forms such as glycosylated derivatives or esters of tartaric acid, shikimic combined forms such as glycosylated derivatives or esters of tartaric acid, shikimic acid, acid, and quinic acid rather than in the free form. Hydroxycinnamic acids are recognized and quinic acid rather than in the free form. Hydroxycinnamic acids are recognised as as powerful antioxidants playing an essential role in protecting the bodybody fromfrom freefree radicals.radicals.Several Several hydroxycinnamic hydroxycinnamic acid acid derivatives, derivatives, such such as as caffeic caffeic acid, acid, chlorogenicchlorogenic acid,acid, ferulicfer- ulicacid, acid,p -coumaricp-coumaric acid, acid, and and sinapic sinapic acid, acid, present present strong strong antioxidant antioxidant activities activities by by inhibiting inhib- itinglipid lipid oxidation oxidation and and scavenging scavenging reactive reactive oxygen oxygen species species (ROS) (ROS) [10 [10].]. Chlorogenic Chlorogenic acid acid and andcaffeic caffeic acid acid inhibit inhibit the the N-nitrosation N-nitrozation reaction reaction and and prevent prevent the the formation formation of of mutagenic mutagenic and andcarcinogenic carcinogenic N-nitroso N-nitroso compounds compounds [20 [20].]. RosemaryRosemary (Rosmarinus (Rosmarinus officinalis ofﬁcinalis L.) L.)extracts extracts have have been been used used as asdiuretic, diuretic, analgesic, analgesic, expectorant,expectorant, antirheumatic, antirheumatic, and and antimutageni antimutagenicc agents. agents. Caffeic Caffeic acid acid and and its itsderivatives, derivatives, suchsuch as rosmarinic as rosmarinic acid acid (Figure (Figure 2) 2and) and chloro chlorogenicgenic acid, acid, have have been been thought thought to tobe bethe the most most importantimportant ones ones responsible responsible for forthe the therapeutic therapeutic properties properties of rosemary of rosemary extracts, extracts, as asthey they havehave antioxidant antioxidant effects effects and and contribute contribute to the to the bioactive bioactive function function of rosemary of rosemary [21]. [21 ].

Figure 2. Chemical structures of rosmarinic acid and chlorogenic acid. Figure 2. Chemical structures of rosmarinic acid and chlorogenic acid. Among the phenolic compounds identified by Zheng and Wang [22], rosmarinic acid wasAmong the predominant the phenolic phenolic compounds compound identified in Salvia by Zheng officinalis and Wangand Thymus [22], rosmarinic vulgaris (Table acid 1). was the predominant phenolic compound in Salvia officinalis and Thymus vulgaris (Table Table 1. Phenolic compounds1). in Salvia officinalis, Thymus vulgaris, and Rosmarinus officinalis (mg/100 g of fresh weight). Data from Zheng and Wang [22]. Table 1. Phenolic compounds in Salvia officinalis, Thymus vulgaris, and Rosmarinus officinalis (mg/100 g of fresh weight). Data from PhenolicZheng and Compounds Wang [22]. Salvia officinalis Thymus vulgaris Rosmarinus officinalis ± ± Vanillic acid 2.27 0.48Thymus vul- Rosmarinus 1.73 0.08 offici- Caffeic acidPhenolic Compounds 7.42 ± 0.35Salvia officinalis 11.7 ± 1.04 2.95 ± 0.12 garis nalis Luteolin 33.4 ± 1.32 39.5 ± 1.53 VanillicRosmarinic acid acid 117.8 ± 1.01 2.27 ± 91.8 0.48± 2.75 32.8 1.73± ±1.69 0.08 CaffeicHispidulin acid 16.3 ± 1.07 7.42 ± 20.8 0.35± 0.96 11.7 ± 1.04 19.7 2.95± ±1.12 0.12 LuteolinCirsimaritin 14.3 ± 0.8333.4 ± 1.32 39.5 ± 1.53 24.4 ± 0.87 RosmarinicCarnosic acid acid 117.8 ± 1.01 91.8 ± 2.75 126.6 32.8± ±6.00 1.69 HispidulinApigenin 2.4 ± 0.07 16.3 ± 1.07 20.8 ± 0.96 1.1 19.7± 0.15± 1.12 CirsimaritinNaringin 14.3 ± 0.83 53.1 24.4± ±2.09 0.87 CarnosicRosmanol acid 124.1 126.6± ±3.19 6.00 Total phenolic (mg of GAE/g of fresh weight) 1.34 ± 0.09 2.13 ± 0.11 2.19 ± 0.15 Apigenin 2.4 ± 0.07 1.1 ± 0.15 ORAC (Oxygen Radical Absorbance Naringin 13.28 ± 0.40 19.49 ± 0.21 19.15 53.1± ±0.63 2.09 Capacity—µmol of TE/g of fresh weight) Rosmanol 124.1 ± 3.19 Total phenolic (mg of GAE/g of fresh weight) 1.34 ± 0.09 2.13 ± 0.11 2.19 ± 0.15 ORAC (Oxygen Radical Absorbance Capacity—µmolIn previous of years, TE/g theof fresh use ofweight) the active 13.28 phenolic ± 0.40 acid 19.49 compounds ± 0.21 (such 19.15 as chlorogenic± 0.63 acid, ferulic acid, cinnamic acid, and rosmarinic acid) in food has increased. Thus, the study of plants’ phytochemicals is important and essential [23]. Coumarins are a large class of C6-C3 derivatives belonging to the benzo-α-pyrone group, which exist in the free or combined form as heterosides and glycosides in certain plants; most of them are isolated from chlorophyll-containing plant materials [24]. Species Foods 2021, 10, x FOR PEER REVIEW 4 of 28

In previous years, the use of the active phenolic acid compounds (such as chlorogenic acid, ferulic acid, cinnamic acid, and rosmarinic acid) in food has increased. Thus, the study of plants’ phytochemicals is important and essential [23]. Coumarins are a large class of C6-C3 derivatives belonging to the benzo-α-pyrone Foods 2021, 10, 106 group, which exist in the free or combined form as heterosides and glycosides in certain4 of 29 plants; most of them are isolated from chlorophyll-containing plant materials [24]. Species rich in coumarins included Aesculus hippocastanum (Horsechestnut), Passiflora incarnata (Passionflower), Lawsonia inermis (Henna), Hypericum perforatum (Saint John Wort), Tilia cordatarich in(Lime coumarins Tree), and included UncariaAesculus tomentosa hippocastanum (Cat’s Claw)(Horsechestnut), [25]. CoumarinsPassiflora can be categorised incarnata (Pas- intosionflower), four types.Lawsonia Simple coumarins inermis (Henna), are theHypericum hydroxylated, perforatum alkoxylated,(Saint Johnand alkylated Wort), Tilia deriv- cordata Uncaria tomentosa atives(Lime of the Tree), benzene and ring of coumarin,(Cat’s and the Claw) corresponding [25]. Coumarins glycosides. can be Furanocouma- categorised into four types. Simple coumarins are the hydroxylated, alkoxylated, and alkylated derivatives rins compounds consist of a five-member furan ring attached to the coumarin nucleus, of the benzene ring of coumarin, and the corresponding glycosides. Furanocoumarins com- divided into linear and angular types with a substituent at one or both remaining ben- pounds consist of a five-member furan ring attached to the coumarin nucleus, divided into zenoid positions. Pyrano coumarins are analogous to the furanocoumarins but contain a linear and angular types with a substituent at one or both remaining benzenoid positions. six-member ring. The last type is coumarins substituted in the pyrone ring [26]. Several Pyrano coumarins are analogous to the furanocoumarins but contain a six-member ring. products that contain a coumarin moiety show excellent biological activities such as anti- The last type is coumarins substituted in the pyrone ring [26]. Several products that contain tumor, antibacterial, antifungal, anticoagulant, vasodilator, analgesic, and anti-inflamma- a coumarin moiety show excellent biological activities such as antitumor, antibacterial, an- tory activities [24,27,28]. tifungal, anticoagulant, vasodilator, analgesic, and anti-inflammatory activities [24,27,28]. Lignans are a diverse group of bioactive phenolic compounds formed of two β-β- Lignans are a diverse group of bioactive phenolic compounds formed of two β-β- linked phenylpropane units; they are present in different parts of plant species in free linked phenylpropane units; they are present in different parts of plant species in free formform or combined or combined form form as glycoside as glycoside derivatives derivatives.. Lignans Lignans are found are found in vegetables in vegetables such suchas in asthe in brassica the brassica family family where where fresh freshedible edible weights weights (mg/100 (mg/100 g) between g) between 0.185 to 0.185 2.32to of2.32 can of be canfound, be found, for instance, for instance, for broccoli for broccoli (98.51), (98.51), Brussels Brussels sprouts sprouts (50.36 (50.36),), cauliflower cauliflower (9.48), (9.48), greengreen cabbage cabbage (0.03), (0.03), red red cabbage cabbage (18.1), (18.1), white white cabbage cabbage (21.51), (21.51), and and kale kale (63). (63). They They can can alsoalso be befound found in ingreen green beans beans (22.67), (22.67), tomato tomato (2.15), (2.15), cucumber cucumber (3.8), (3.8), zucchini zucchini (7.02), (7.02), green green lettucelettuce (1.17), (1.17), and and carrot carrot (7.66). (7.66). However, However, spinach, spinach, white white potatoes, potatoes, and mushrooms containcon- tainan an amount amount below below 0.1 0.1 mg/100 mg/100 gg (fresh(fresh edibleedible weight) of lignin [29,30]. [29,30]. Lignan Lignan presents presents a a greatgreat antioxidant antioxidant activity activity and may be effectiveeffective inin thethe treatmenttreatment of of cardiovascular cardiovascular disease, disease,coronary coronary heart heart disease, disease, and and diabetes diabetes [31 [31].]. 6 3 6 6 FlavonoidsFlavonoids have have the the general general structural structural C C-C6-C-C3-C, in6, which in which the the two two C Cunits6 units are are phe- phe- nolicnolic and and linked linked by bya C a3 Cgroup.3 group. They They can can be bedivided divided into into flavones, flavones, flavonols, flavonols, flavanones, flavanones, andand flavanols, flavanols, according according to the to theoxidation oxidation state state of the of central the central pyran pyran ring, ring,as well as as well in an- as in thocyaninsanthocyanins and isoflavonoids, and isoflavonoids, with different with different antioxidant, antioxidant, antibacterial, antibacterial, antiviral, antiviral, and an- and ticanceranticancer activities activities [15,32]. [15 ,32]. FlavonesFlavones usually usually occur occur as asglycosides glycosides of ofapigenin apigenin and and luteolin luteolin in inplants plants (Figure (Figure 3).3 ). FlavonesFlavones are are found found in incelery celery (22–108 (22–108 mg/kg mg/kg fresh fresh weight) weight) and and showed showed the the proprieties proprieties of of loweringlowering the the levels levels of oftotal total and and low-density low-density lipoprotein lipoprotein (LDL) (LDL) cholesterol cholesterol and and also also have have anti-inflammatoryanti-inflammatory and and anticancer anticancer activities activities [33]. [33 In]. Inother other vegetables, vegetables, the the amounts amounts are are (mg/kg(mg/kg of luteolin of luteolin and and apigenin, apigenin, respectively): respectively): 0.41 0.41 and and 0.05 0.05 in inwater water spinach; spinach; 0.09 0.09 and and 0.030.03 in incucumber; cucumber; 0.16 0.16 and and 1.07 1.07 in inpurple purple cabbage; cabbage; 1.18 1.18 and and 0.31 0.31 in inchinese Chinese cabbage; cabbage; 0.16 0.16 andand 0.92 0.92 in inwhite white cabbage cabbage and and 0.22 0.22 and and 0.04 0.04 in inonion onion [34]. [34 ].

Figure 3. Structures of the major ﬂavones. Figure 3. Structures of the major flavones. Flavonols have been extensively studied and are extensively distributed in plants [35–44]. They are frequently the conjugated form of glycosides such as kaempferol, quercetin, and myricetin (Figure4). Quercetin levels in the edible parts of most vegetables are generally (of fresh weight, mg/kg) below 10, except for onions (284–486), kale (110), broccoli (30), French beans (32–45), and slicing beans (28–30) [35]. Kaempferol could only be detected (fresh edible weight, mg/kg) in kale (211), endive (15–91), leek (11–56), and turnip tops (31–64) [35]. A rich source of flavonols are onion leaves that contain (fresh weight, mg/kg) 1.497 of quercetin and 832 of kaempferol [37], and also sweet potato leaves (purple) showed Foods 2021, 10, x FOR PEER REVIEW 5 of 28

Flavonols have been extensively studied and are extensively distributed in plants [35–44]. They are frequently the conjugated form of glycosides such as kaempferol, quercetin, and myricetin (Figure 4). Quercetin levels in the edible parts of most vegetables are generally (of fresh weight, mg/kg) below 10, except for onions (284–486), kale (110), broccoli (30), French beans (32–45), and slicing beans (28–30) [35]. Kaempferol could only be detected (fresh edible weight, mg/kg) in kale (211), endive (15–91), leek (11–56), and turnip Foods 2021, 10, 106 5 of 29 tops (31–64) [35]. A rich source of flavonols are onion leaves that contain (fresh weight, mg/kg) 1.497 of quercetin and 832 of kaempferol [37], and also sweet potato leaves (purple) showed 156 mg/kg of myricetin and 267 mg/kg of quercetin [34]. According to Erlund [45],156 quercetin mg/kg ofis myricetinan antioxidant and 267 protecting mg/kg of quercetin against [reactive34]. According oxygen to Erlundspecies [45 and], quercetin shows also antiatherosclerosis,is an antioxidant protecting anticancer, against anti-inflamma reactive oxygentory, species and and cholesterol-lowering shows also antiatherosclerosis, properties. anticancer, anti-inflammatory, and cholesterol-lowering properties. Flavanones are colourless Flavanones are colorless compounds characterized by the absence of a double bond in the compounds characterised by the absence of a double bond in the 2, 3-position of the pyrone 2, 3-positionring, and areof the isomeric pyrone with ring, chalcones. and are Low isomeric concentrations with chalcones. of flavanones, Low namely concentrations naringenin, of flavanones,are found namely in tomatoes naringenin, [46]. are found in tomatoes [46].

FigureFigure 4. Structures 4. Structures of the of the major major flavonol ﬂavonol aglycones. aglycones.

Monomeric flavan-3-ols include catechin, epicatechin, gallocatechin, catechin gal- Monomeric flavan-3-ols include catechin, epicatechin, gallocatechin, catechin gallate, late, epicatechin gallate, epigallocatechin, epigallocatechin-3-gallate, and gallocatechin epicatechingallate (Figure gallate,5). epigallocatechin, Catechin and epicatechin epigallocatechin-3-gallate, are the most abundant and flavanols gallocatechin found gallate in (Figurefruits, 5). while Catechins in the seedsand epicatechin of some leguminous, are the most the most abundant abundant flavanols flavanols found are gallocat- in fruits, whileechin, in the epigallocatechin, seeds of some and leguminous, epigallocatechin the most gallate abundant [47]. In flavanols fava beans are (Vicia gallocatechin, faba L.), epigallocatechin,(−)-epicatechin and and epigallocatechin epigallocatechin were gallate detected [47]. In by fava Helsper beans et al. (Vicia [48]. faba A general L.), (− trend)-epicat- echinof and increasing epigallocatechin “total catechin were equivalent” detected contentby Helsper with et increasing al. [48]. A darkness general of trend the legumes of increasing “totalwithin catechin one family equivalent” can be observed content [49 with,50]. Allincreasing types of darkness beans, and of mature the legumes seeds con- within one tainfamily flavan-3-ols can be observed (mg/100 g,[49,50]. edible All portion)—namely, types of beans, (+)-catechin and mature (1.66); seeds (−)-epicatechin contain flavan- (0.35) [51] and beans, pinto, mature seeds, raw (Phaseolus vulgaris) (+)-catechin (5.07); (−)- 3-ols (mg/100 g, edible portion)—namely, (+)-catechin (1.66); (−)-epicatechin (0.35) [51] epicatechin (0.14); (−)-epigallocatechin (0.05 mg/100 g) [52], broad beans, immature seeds, and rawbeans, (Vicia pinto, faba ),mature (−)-epicatechin seeds, raw (28.96); (Phaseolus (−)-epigallocatechin vulgaris) (+)-catechin (15.47); (+)-catechin(5.07); (−)-epicatechin (14.29); (0.14);(+)-gallocatechin (−)-epigallocatechin (4.15) [51 (0.05,52]. Catechinmg/100 g) prevents [52], broad protein beans, oxidation immature by its free seeds, radical raw scav- (Vicia faba),enging (−)-epicatechin capacity. Furthermore, (28.96); (−)-epigallocatechin it possesses the ability (15.47); to reduce (+)-catechin the covalent (14.29); modification (+)-gallocat- echinof (4.15) protein [51,52]. induced Catechin by reactive prevents oxygen protei speciesn (ROS) oxidation or by-products by its free of radical oxidative scavenging stress [53]. capacity. Furthermore, it possesses the ability to reduce the covalent modification of protein induced by reactive oxygen species (ROS) or by-products of oxidative stress [53].

Foods 2021, 10, 106 6 of 29

Foods 2021, 10, x FOR PEER REVIEW 6 of 28

Figure 5. Structures of monomeric flavan-3-ols. Figure 5. Structures of monomeric flavan-3-ols. FigureIsoflavonoids 5. Structures are flavonoidsof monomeric that flavan-3-ols. have their B ring fused with the C3 position of ring C, whichIsoflavonoids are phenolics are with flavonoids phytoestrogenic that have their activity B ring (Figure fused with6). The the concentrations C3 position of ring of iso-

flavonesC, which in soybean are phenolics products with ranged phytoestrogenic from 580 activityto 3800 (Figuremg/kg6 of). Thefresh concentrations weight [54]. of isoﬂavones in soybean products ranged from 580 to 3800 mg/kg of fresh weight [54].

Figure 12. Chemical structure of (E)-2-nonenal and (Z)-3-hexenal.

Figure 6. Chemical structures of isoﬂavonoids. Figure 6. Chemical structures of isoflavonoids. The basic structures of anthocyanins are anthocyanidins, in which the two aromatic ringsThe basic A and structures B are linked of byanthocyanins a heterocyclic are ring anthocyanidins, C that possesses in oxygen. which the More two than aromatic 23 ringsdifferent A and anthocyanidinsB are linked by have a beenheterocyclic found with ring pelargonidin, C that possesses cyanidin, oxygen. peonidin, More delphini- than 23 differentdin, petunidin, anthocyanidins and malvidin have beingbeen thefound most with common pelargonidin, (Figure7). Anthocyanins cyanidin, peonidin, in plants delphinidin,mainly petunidin, exist in conjugated and malvidin form as being glycosides. the most Monomeric common anthocyanin (Figure 7). changed Anthocyanins the hy- in droxylation and methoxylation patterns on the B ring; the nature, position, and the number plants mainly exist in conjugated form as glycosides. Monomeric anthocyanin changed of conjugated sugar units; the nature and number of conjugated aliphatic or aromatic acid the hydroxylationgroups; the existence and methoxylation or lackFigure of an acyl 13patterns. Chemical aromatic on the group structure B ring; in the ofthe molecule3-butylphthalide. nature, [position,55]. They and are the numberusually of conjugated present in any sugar pink units; to purple the nature vegetables andsuch number as black of conjugated beans (Phaseolus aliphatic vulgaris or) aromatic(delphinidin acid groups; (11.98); the malvidinexistence (6.45); or lack petunidin of an (9.57)acyl aromatic in mg/100 group g, edible in portion);the molecule kidney [55]. Theyred are beans usually (Phaseolus present vulgaris in any) (pelargonidin pink to purple (2.42); vegetables cyanidin (1.19) such in as mg/100 black beans g, edible (Phaseolus por- vulgaristion)) [(delphinidin56]; common raw(11.98); beans malvidin (Phaseolus (6.45); vulgaris petunidinvar. Zolﬁno) (9.57) (delphinidin in mg/100 (2.50); g,malvidin edible portion);(0.10); kidney petunidin red beans (0.14) (Phaseolus in mg/100 vulgaris g, edible) portion)(pelargonidin [38]; redraw (2.42); cabbage cyanidin(Brassica (1.19) oleracea in mg/100) g, edible(cyanidin portion) (72.86), [56]; delphinidin common (0.01); raw pelargonidin beans (Phaseolus (0.02) in vulgaris mg/100 var. g, edible Zolfino) portion) (delphinidin [42,56] (2.50); malvidin (0.10); petunidin (0.14) in mg/100 g, edible portion) [38]; redraw cabbage (Brassica oleracea) (cyanidin (72.86), delphinidin (0.01); pelargonidin (0.02) in mg/100 g, edible portion) [42,56] and in cowpeas (blackeyes, crowder, southern) (Vigna unguiculata) (cyanidin (94.72); delphinidin (94.60); malvidin (34.28); peonidin (11.07); petunidin (27.82) in mg/100 g, edible portion) [57]. The protective effects of anthocyanins include an-

tiedema, antioxidant, anti-inflammatory, and anticarcinogenic activities [58]. Figure 14. Chemical structure of 2-isobutyl 3-methoxypyrazine and 3-sec-butyl-2-methoxypyrazine.

Figure 7. Chemical structures of anthocyanidins.

Condensed tannins, also recognized as proanthocyanidins, mainly comprise a flavan-3-ol unit to form dimers, oligomers, and polymers of up to 50 monomer units (Figure 8). Proanthocyanidins have complex structures depending on the number of the flavan-3- ol units, the location and type of interflavan linkage in the molecule, and the nature and position of substituents on the flavan-3-ol unit. Proanthocyanidins can be classified into procyanidins and prodelphinidins based on their hydroxylation patterns of A and B rings [33]. The proanthocyanidin contents in spinach (Spinacea oleracea) and radish leaves

Foods 2021, 10, x FOR PEER REVIEW 6 of 28

Figure 5. Structures of monomeric flavan-3-ols.

Isoflavonoids are flavonoids that have their B ring fused with the C3 position of ring C, which are phenolics with phytoestrogenic activity (Figure 6). The concentrations of isoflavones in soybean products ranged from 580 to 3800 mg/kg of fresh weight [54].

Figure 6. Chemical structures of isoflavonoids.

The basic structures of anthocyanins are anthocyanidins, in which the two aromatic rings A and B are linked by a heterocyclic ring C that possesses oxygen. More than 23 different anthocyanidins have been found with pelargonidin, cyanidin, peonidin, delphinidin, petunidin, and malvidin being the most common (Figure 7). Anthocyanins in plants mainly exist in conjugated form as glycosides. Monomeric anthocyanin changed the hydroxylation and methoxylation patterns on the B ring; the nature, position, and the number of conjugated sugar units; the nature and number of conjugated aliphatic or aromatic acid groups; the existence or lack of an acyl aromatic group in the molecule [55]. They are usually present in any pink to purple vegetables such as black beans (Phaseolus vulgaris) (delphinidin (11.98); malvidin (6.45); petunidin (9.57) in mg/100 g, edible portion); kidney red beans (Phaseolus vulgaris) (pelargonidin (2.42); cyanidin (1.19) in mg/100 g, edible portion) [56]; common raw beans (Phaseolus vulgaris var. Zolfino) (delphinidin Foods 2021, 10, 106 (2.50); malvidin (0.10); petunidin (0.14) in mg/100 g, edible portion) [38]; redraw7 of 29cabbage (Brassica oleracea) (cyanidin (72.86), delphinidin (0.01); pelargonidin (0.02) in mg/100 g, edible portion) [42,56] and in cowpeas (blackeyes, crowder, southern) (Vigna unguiculata) (cyanidinand in cowpeas (94.72); (blackeyes, delphinidin crowder, (94.60); southern) malvidin (Vigna (34.28); unguiculata peonidin) (cyanidin (11.07); petunidin (94.72); del- (27.82) inphinidin mg/100 (94.60); g, edible malvidin portion) (34.28); [57]. peonidin The protective (11.07); petunidin effects (27.82) of anthocyanins in mg/100 g, edibleinclude antiedema,portion) antioxidant, [57]. The protective anti-inflammatory, effects of anthocyanins and anticarcinogenic include antiedema, activities antioxidant, [58]. anti- inﬂammatory, and anticarcinogenic activities [58].

Figure 7. Chemical structures of anthocyanidins. Figure 7. Chemical structures of anthocyanidins. Condensed tannins, also recognised as proanthocyanidins, mainly comprise a flavan- 3-olCondensed unit to form tannins, dimers, oligomers,also recognized and polymers as proanthocyanidins, of up to 50 monomer mainly units (Figurecomprise8). a flavan-3-olProanthocyanidins unit to form have dimers, complex oligomers, structures and depending polymers on of theup numberto 50 monomer of the flavan-3- units (Figure ol units, the location and type of interflavan linkage in the molecule, and the nature 8). Proanthocyanidins have complex structures depending on the number of the flavan-3- and position of substituents on the flavan-3-ol unit. Proanthocyanidins can be classified olinto units, procyanidins the location and and prodelphinidins type of interflava basedn on linkage their hydroxylation in the molecule, patterns and of the A andnature B and positionrings [33 of]. Thesubstituents proanthocyanidin on the flavan-3-ol contents in spinachunit. Proanthocyanidins (Spinacea oleracea) and can radish be classified leaves into procyanidins(Raphanus sativus and) areprodelphinid 88.46 and 13.57ins based proanthocyanidins on their hydroxylat in mg/100ion g patterns fresh weight, of A respec- and B rings [33].tively The [59 ].proantho Proanthocyanidinscyanidin contents have antioxidant in spinach activity (Spinacea responsible oleracea for cardioprotection,) and radish leaves cancer chemoprevention, and lowering cholesterol amounts [33].

Procyanidins: n > 0

Oligomeric procyanidins: n = 0–7

Figure 8. Chemical structure of procyanidins. Figure 8. Chemical structure of procyanidins Quinones are phenolic compounds with conjugated cyclic dione structures, such as that of benzoquinones, derived from aroma compounds by the conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double bonds. The most common skeletal structures of quinones found in plants are p-quinone, o-quinone, anthraquinone, naphthoquinone, and naphtodianthrone (Figure9). Foods 2021, 10, x FOR PEER REVIEW 7 of 28

(Raphanus sativus) are 88.46 and 13.57 proanthocyanidins in mg/100g fresh weight, respectively [59]. Proanthocyanidins have antioxidant activity responsible for cardioprotection, cancer chemoprevention, and lowering cholesterol amounts [33].

Figure 8. Chemical structure of procyanidins.

Quinones are phenolic compounds with conjugated cyclic dione structures, such as that of benzoquinones, derived from aroma compounds by the conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of dou- Foods 2021, 10, 106 ble bonds. The most common skeletal structures of quinones found in plants8 of are 29 p-quinone, o-quinone, anthraquinone, naphthoquinone, and naphtodianthrone (Figure 9).

Figure 9. Quinone structures. Figure 9. Quinone structures. Stilbenes are a group of phenolic compounds that share a similar chemical structure to flavonoids,Stilbenes in are which a group the two of phenolic aromatic rings compound (A and B)s that are linkedshare bya similar a methylene chemical bridge. structure toOne flavonoids, of the most in aromawhichcompounds the two aromatic stilbenes rings is present (A and mostly B) are inlinked glycosylated by a methylene forms is bridge. Onetrans -resveratrolof the most (Figure aroma 10 compounds). Resveratrol isstilbenes a phytoalexin is present that has mostly been particularly in glycosylated studied forms is transas it-resveratrol shows several (Figure biological 10). activities, Resveratrol reduces is a phytoalexin the formation that of atherosclerotic has been particularly plaque, stud- present neuroprotective, antidiabetic, anti-inflammatory, antioxidant, anticarcinogenic Foods 2021, 10, x FOR PEER REVIEWied as it shows several biological activities, reduces the formation of atherosclerotic 8 of 28 effects, and antiviral activity [60,61]. It was also shown in several studies that trans-piceid plaque, present neuroprotective, antidiabetic, anti-inflammatory, antioxidant, anticar- a 3-β-glucosylated form of trans-resveratrol could inhibit platelet aggregation [62,63] and cinogenicoxidation ofeffects, human and low-density antiviral lipoprotein activity [60,61 (LDL).]. Peng It was et al. also [64] shown showed in that severaltrans-piceid studies that transwas the-piceid major a form3-β-glucosylated existing in most form vegetables, of trans-resveratrol and most of the could samples inhibit contained platelet higher aggregation in µg/100 g fresh weight lies between 1.14 and 0.70 in cauliflower and 1.78 and 23.12 in [62,63]trans-piceid and oxidation than trans-resveratrol. of human low-density The concentration lipoprotein of trans (LDL).-resveratrol Peng inetµ al.g/100 [64]g showed thatcelery,fresh trans weight as-piceid well lies betweenas was 8.8 the and 1.14 major 19.74 and form 0.70 in inblackexisting cauliflower soya in most bean. and vegetables, 1.78 As and for 23.12 trans-piceid, and in celery,most of as itthe well is samples between 43.04 containedandas 8.8 783.29 and higher 19.74 in celery, in trans black-piceid 0.80 soya and bean.than 9.22 trans As forin-resveratrol. leaftrans -piceid,lettuce, The it 1.10 is concentration between and 12.0 43.04 in of and tomato,trans 783.29-resveratrol and 18.16 and 194.40in celery, in 0.80 red and radish 9.22 in [64]. leaf lettuce,According 1.10 and to 12.0Sebastià in tomato, et al. and [65], 18.16 the and concentration 194.40 in of trans- resveratrolred radish [64 in]. Accordingtomatoes tois Sebasti0.2 µg/g.à et al. [65], the concentration of trans-resveratrol in tomatoes is 0.2 µg/g.

Figure 10. Chemical structure resveratrol. Figure 10. Chemical structure resveratrol. Flavonoids are largely distributed in vegetables and they have been studied mainly because of their potential health benefits as antioxidants and chemopreventive agents [48]. However,Flavonoids until now are no largely recommended distributed daily intake in vegeta of thesebles compounds and they has have been been estab- studied mainly becauselished mainly of their because potential the composition health benefits data are as incomplete, antioxidants the biologicaland chemopreventive activities are agents [48]. However,not well determined, until now and no especially recommended because the daily bioavailability intake of and these pharmacokinetic compounds data has been estab- lishedare inconclusive. mainly because Emerging the science composition from some studiesdata are suggests incomplete, that flavonoid-rich the biological diets activities are may lower the risk of some diet-related chronic degenerative diseases [66–68] but a few notclinical well and determined, laboratory reports and indicateespecially that because very high dosesthe bioavailability of certain flavonoids and may pharmacokinetic have data areadverse inconclusive. effects [69,70 Emerging]. Therefore, science it is important from some to accurately studies assess suggests flavonoid that intakesflavonoid-rich diets mayfrom lower the perspectives the risk ofof bothsome disease diet-related prevention chro andnic safety degenerative [71,72]. The specificdiseases action [66–68] but a few clinicalof each phenolicand laboratory compound reports from vegetables indicate and that medicinal very high and aromaticdoses of plants certain is not flavonoids may have adverse effects [69,70]. Therefore, it is important to accurately assess flavonoid intakes from the perspectives of both disease prevention and safety [71,72]. The specific action of each phenolic compound from vegetables and medicinal and aromatic plants is not easy to measure since only a small part of it is truly absorbed and, also, it may potentially transform [73]. Numerous dietary phenolic compounds are antioxidants able to quench ROS and toxic free radicals formed from the peroxidation of lipids and, consequently, have anti-inflammatory and antioxidant properties. Flavonoids are recognized as preventing the production of free radicals by chelating iron and copper ions to directly scavenge ROS and toxic free radicals and inhibit lipid peroxidation, which may damage DNA, lipids, and proteins, linked to ageing, atherosclerosis, cancer, inflammation, and neurodegenerative diseases [74]. Many of these reported biological functions have been attributed to free radical scavenging activity and there has been intensive research on the natural antioxidants derived from plants [32,75–77]. Hundreds of epidemiological studies have correlated the antioxidant, anticancer, antibacterial, cardioprotective, anti-inflammation, and immune system promoting roles of plants enhanced by phenolic content. Tables 2 and 3 summarise important bioactivities related to the presence of phenolic identified in vegetables and MAPs widely consumed in the world. For example, Salem et al. [78] found that extracts of artichokes rich in polyphenols were capable of inhibiting the production of histamine, bradykinin, and chemokines. These authors discovered that polyphenols present in extracts were capable of acting synergistically, enhancing their anti-inflammatory potential. Ad- ditionally, Sharma et al. [79] observed that extracts of onion were capable of inhibiting the bacterial growth of Staphylococcus sp. and Escherichia coli, due to the presence of quercetin aglycone, quercetin-4′-O-monoglucoside, and quercetin-3,4′-O-diglucoside. However, the intensity of the antagonistic effect was dependent on the concentration of each compound in each onion variety assessed. In 2018, Dzotam et al. [80], using extracts of nutmeg rich in 7-trihydroxyflavone, observed an antibacterial activity of such extracts against the multidrug resistant Gram-negative bacteria Providencia stuartii and Escherichia coli. A recent study showed that thymus extract rich in rosmarinic acid and 3,4-dihydroxybenzoic acid was capable of exhibiting antiradical and antioxidant properties and enhanced gastrointestinal digestion [81].

Foods 2021, 10, 106 9 of 29

easy to measure since only a small part of it is truly absorbed and, also, it may potentially transform [73]. Numerous dietary phenolic compounds are antioxidants able to quench ROS and toxic free radicals formed from the peroxidation of lipids and, consequently, have anti-inflammatory and antioxidant properties. Flavonoids are recognised as preventing the production of free radicals by chelating iron and copper ions to directly scavenge ROS and toxic free radicals and inhibit lipid peroxidation, which may damage DNA, lipids, and proteins, linked to ageing, atherosclerosis, cancer, inflammation, and neurodegenerative diseases [74]. Many of these reported biological functions have been attributed to free radical scavenging activity and there has been intensive research on the natural antioxidants derived from plants [32,75–77]. Hundreds of epidemiological studies have correlated the antioxidant, anticancer, antibacterial, cardioprotective, anti-inflammation, and immune system promoting roles of plants enhanced by phenolic content. Tables2 and3 summarise important bioactivities related to the presence of phenolic identified in vegetables and MAPs widely consumed in the world. For example, Salem et al. [78] found that extracts of artichokes rich in polyphenols were capable of inhibiting the production of histamine, bradykinin, and chemokines. These authors discovered that polyphenols present in extracts were capable of acting synergistically, enhancing their anti-inflammatory potential. Addi- tionally, Sharma et al. [79] observed that extracts of onion were capable of inhibiting the bacterial growth of Staphylococcus sp. and Escherichia coli, due to the presence of quercetin aglycone, quercetin-40-O-monoglucoside, and quercetin-3,40-O-diglucoside. However, the intensity of the antagonistic effect was dependent on the concentration of each compound in each onion variety assessed. In 2018, Dzotam et al. [80], using extracts of nutmeg rich in 7- trihydroxyflavone, observed an antibacterial activity of such extracts against the multidrug resistant Gram-negative bacteria Providencia stuartii and Escherichia coli. A recent study showed that Thymus extract rich in rosmarinic acid and 3,4-dihydroxybenzoic acid was capable of exhibiting antiradical and antioxidant properties and enhanced gastrointestinal digestion [81]. Foods 2021, 10, 106 10 of 29

Table 2. Phenolic compounds present in some vegetables consumed worldwide and the main bioactivities pointed.

Vegetables Main Phenolics Bioactivities Pointed Ref. Anti-inflammatory activities of C. scolymus were found due to the Artichoke Hydroxytyrosol, verbascoside, apigenin-7-glucoside, oleuropein, synergistic effect of phenolic compounds. Inhibitory action of artichoke [78] (Cynara scolymus L.) quercetin, pinoresinol, and apigenin extracts in the inflammatory process such as histamine, bradykinin, and chemokine mediators’ processes was related to the phenolic content. Hydroxybenzoic acid, hydroxycinnamic acid, flavone, polymethoxylated flavone, kaempferol glycosylated and kaempferol Hydroalcoholic extracts were capable of directly reacting with and Broccoli florets derivatives, quercetin-3-O-glucoside and derivatives, quenching DPPH and Oxygen (ORAC) radicals. Flavonoids and derivatives [82] (Brassica oleracea L. var. italica) isorhamnetin-3-O-rutinoside, isorhamnetin glucoside, and related showed significant positive correlations to DPPH, and ORAC. compounds Antioxidant activity was highly correlated with the presence of apiin, Celery High content of apiin, apigenin, and rutin, 3,7-dihydroxyflavone, apigenin, and rutin, mainly due to the lower BDE of O–H bonds in their B [83] (Apium graveolens L.) cyanidin and diosmetin, and terpenes (α-ionone) rings, which enhanced their H atom donating ability. The high content of total phenolic content, A positive and significant correlation between the content of total phenolic Garlic vanillic acid, caffeic acid, content and antimicrobial and antioxidant activity was found. The highest [84,85] (Allium sativum L.) p-coumaric acid, ferulic acid, sinapic acid, total phenolics content was significantly correlated with the lowest EC50 cyanidin-3-(60-malonyl)-glucoside) values for all the tested antioxidant activity assays. The antioxidant capacity in the lipophilic fraction was higher than those in Ginseng leaves Gallic acid and galangin hydrophilic fractions and positive correlations between antioxidant capacity [86] (Panax ginseng C. A. Mey.) and total phenolic content, gallic acid, and galangin were found. Extracts showed a favourable antimicrobial activity against Staphylococcus Leek Rosmarinic acid, quercetin, and apigenin glycosylated forms and aureus, Bacillus subtilis, and Aspergillus niger. Extracts inhibit Hep2c, L2OB, [87] (Allium porrum L.) respective derivatives and RD tumor cells in a dose-dependent manner after 48 h treatment period. The antioxidant activity of onions was dependent on variation in the Onion Quercetin aglycone, quercetin-40-O-monoglucoside, and contents of quercetin compounds in all onion varieties assessed. [79] (Allium cepa L.) quercetin-3,40-O-diglucoside Antibacterial activity against Staphylococcus sp. and Escherichia coli was dependent on variation in both phenolic profile and content. The radical scavenging activity (RSA) of root, stem, and leaves of watercress Watercress Coumaric acid, sinapic acid, caftaric acid, quercetin, and quercetin methanolic extracts were highly correlated with the variation of phenolics. [88] (Nasturtium officinale L.) derivatives were the major phenolic compounds identified Watercress leaves had similar antioxidant potential to that of tocopherol. Foods 2021, 10, 106 11 of 29

Table 3. The key role of some important phenolics identiﬁed in some medicinal and aromatic plant (MAP) species extracts and respective bioactivities.

MAP Extracts Main Phenolics Identified Bioactivities Pointed Ref. Antimicrobial activity against Proteus mirabilis Hauser, Fern Proteus vulgaris Hauser, and Pseudomonas aeruginosa (Schroeter). 7-O-hexoside and quercetin-7-O-rutinoside [89] (Asplenium nidus L.) Migula was shown when fern extracts were applied at different concentrations. Ginkgo leaves Ginkgo leaf extracts were capable of decreasing sunburn symptoms Quercitin-3-O-glucoside [90] (Ginkgo biloba L.) in UVB-induced skin in vivo models. Procyanidin B1, B2, B3, procyanidin trimer, fangchengbisflavan A Green tea Antiradical and antioxidant activity against in vitro studies was and B, catechin 7-O-β-glucopyranoside, epicatechin, (−)-epicatechin [91] (Camellia fangchengensis Liang and Zhong) shown. gallate, epigallocatechin, and epicatechin 3-(3-O-methyl) gallate Haskap berry Cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside, chlorogenic acid, Extracts exhibited comparable anti-inflammatory effects to [92] (Lonicera caerulea L.) quercitin-3-O-rutinoside, quercitin-3-O-glucoside, and catechin diclofenac which is a COX inhibitory medicine. Antibacterial activity of nutmeg extracts against the multidrug Nutmeg 30,40,7-trihydroxyflavone resistant Gram-negative bacteria Providencia stuartii Ewing and [80] (Myristica fragrans Houtt) Escherichia coli was observed. Lavandula Exhibited highest anti-inflammatory activity in rat RAW 264.7 Caffeic acid, luteolin-7-O-glucuronide, and rosmarinic acid [93] (Lavandula pedunculata Mill.) macrophages by inhibiting nitric oxide production. Antioxidant and antiradical activities were observed. Exerted a Isorhamnetin-3-O-hexoside, carnosic acid, carnosol, rosmanol, Rosemary direct cytocidal effect via upregulation of nitric oxide (NO) in cancer epirosmanol, rosmaridiphenol, rosmarinic acid, and their methoxy [94] (Rosmarinus officinalis L.) cells, which in turn acts in a proapoptotic manner and induces cell derivatives apoptosis. The hydroalcoholic extract shows antioxidant activity in vitro and Oregano Rosmarinic acid, 3,4-dihydroxybenzoic acid in vivo models. The oral formulation of oregano preserves [81] (Origanum vulgare L.) antioxidant activity from gastrointestinal digestion. Rosmarinic acid, caffeoyl rosmarinic acid, eriodictyol hexoside, Methanolic extracts were found to possess substantial antioxidant Thymus kaempferol-O-hexoside, kaempferol-O-hexuronide, and antiacetylcholinesterase activities which were correlated to their [95] (Thymus algeriensis Boiss. and Reut) luteolin-O-hexuronide, apigenin-C-di-hexoside, and phenolic contents; however, significant variations were observed apigenin-O-hexuronide between populations. Antioxidant and antiradical activities were observed. Sage extracts Sage Apigenin, carnosic acid, carnosol, rosmanol, epirosmanol, were capable of exerting a direct cytocidal effect via upregulation of [94] (Salvia officinalis L.) rosmarinic acid, and their methoxy derivatives nitric oxide (NO) in cancer cells, in a proapoptotic manner which induced cell apoptosis. Foods 2021, 10, 106 12 of 29

2.1. Polyphenols as Prebiotics As mentioned previously, polyphenols are natural compounds present in many vegetables and MAPs. In the human body, the majority of polyphenols have poor absorptions and they are retained in the intestine for more time where they can promote beneficial effects, specifically by affecting the gut microbiota [96–98]. This leads to a mutual reaction between polyphenolic compounds and gut microbiota. The polyphenols are biotrans- formed into low-molecular-weight phenolic metabolites by gut microbiota resulting in an increase in polyphenol’s bioavailability, responsible for the health effects derived from the consumption of polyphenol-rich plants, which may differ from the native compound found in the plants [97–102]. The properties of polyphenols are dependent on the bioactive metabolites produced when they are metabolised by the microbiota [103]. At the same time, specific polyphenols can modulate the gut microbial composition frequently by the inhibition of pathogenic bacteria and increase the growth of beneficial bacteria resulting in changes of gut microbial composition [104–107]. Finally, they may act as prebiotic metabolites and enhance the beneficial bacteria. It was demonstrated in animal studies that the consumption of polyphenols, especially catechin, anthocyanins, and proanthocyanidins, increases the abundance of Lactobacillus, Bifidobacterium, Akkermansia, Roseburia, and Faecalibacterium spp. [108]. Prebiotics were defined in 1995 as “nondigestible food constituents that beneficially act in the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species, already resident in the colon” [109]. Later, in 2010, prebiotics was defined as “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora, benefits upon host well-being and health” [110]. Bioavailability of polyphenols is influenced by their structural characteristics, mainly by their degree of poly- merisation [111,112]—for example, proanthocyanidins are not absorbed by the intestinal mucosa [112], only aglycones and some glucosides can be absorbed [113]. Additionally, the prebiotic effect of each polyphenol can be influenced by the plant source and the characteristic of the chemical structure of the compound, along with the individual differences in gut microbiota compositions [114].

2.2. Advances in Phenolic Compounds and Future Research Perspectives As plant bioactive phenolic compounds have received increasing attention in recent years [115,116], the research concerning their biosynthesis, biological activities, extraction, purification processes, and chemical characterisations are of the utmost interest. New analytical strategies, such as Nuclear magnetic resonance (NMR) and Mass spectrometry (MS), have demonstrated their use in the identification of new molecular structures and characterisation of plant phenolic profiles [117]. Recently, Jacobo-Velázquez et al. [118] focused on most recent advances in plant phenolic research such as the functional characterisation of enzymes involved in the biosynthesis of flavonoids; the evaluation of pre- and postharvest treatments to increase the phenolic concentrations of different plants and the chemical characterisation of the phenolic profiles from different plants, and the evaluation of their bioactivities. Therefore, the development of analytical methods for exploring qualitative or quantitative approaches to analyse these bioactive phenolic compounds, in different plants, is essential. Sample preparation and optimisation of the extraction process (solid–liquid extraction, ultrasound-assisted extractions, microwave-assisted extractions, supercritical fluid extraction) are essential for achieving higher accuracy of results [119–121]. According to Swallah et al. [122] it is difficult to choose a universal method for the preparation and extraction of phenolic compounds from different plants, as they have different polarities, molecular structures, concentrations, hydroxyl groups, and several aromatic rings involved. Their analysis can be carried out by using different methods such as spectrophotometry, gas chromatography, liquid chromatography, thin-layer chromatography, capillary elec- trophoresis, and near-infrared spectroscopy, which are required to develop rapid, sensitive, and reliable methods [123,124]. Another challenge is the analysis of polymeric phenolic compounds, as their polydispersity results in poor resolution and detection, an example Foods 2021, 10, 106 13 of 29

of which is proanthocyanidins, which have polydisperse structures for which method development is needed; consequently, characterising the unknown phenolic is one of the main challenges in the research on plant polyphenols [117].

3. Plant Volatile Compounds Responsible for Aromatic Features 3.1. Vegetable Volatile Compounds More than 730 flavour compounds have been identified in vegetables [125–129], including some nonvolatile compounds. For example, in tomatoes more than 400 volatile and nonvolatile compounds are known, although only 30 are present in concentrations higher than 1 µL/L, as summarised in different studies [130–132]. Nonetheless, lower concentrations of volatile compounds must be considered, because one compound could be lower than 1µL/L but odour active. In pepper, the “sweetness”, “spicy”, “floral”, and “herbal” characteristics are caused by a mixture of volatile compounds—(Z)-3-hexenal, 2- heptanone, (Z)-2-hexenal, (E)-2-hexenal, hexanol, (Z)-3-hexanol, (E)-2-hexenol, and linalool and nonvolatile compounds (fructose and glucose) [133]. In vegetables, the presence of flavour and nonflavour compounds are diverse, but the key volatile compounds related to the typical sensory properties of vegetables and their respective aromatic features are summarised in Table4. Foods 2021, 10, 106 14 of 29

Table 4. Key volatile and nonvolatile compounds present in some vegetables largely consumed worldwide. The sensory attributes were adapted from Parker et al. [126] and Maarse [134].

Vegetables Key-Volatile Compounds Sensory Attributes Ref. Methanethiol, hydrogen sulphide, dimethyl disulphide, trimethyl disulphide, dimethyl Broccoli sulphide, hexanal, (Z)-3-hexen-1-ol, nonanal, ethanol, 4-methylthiobutyl isothiocyanate, butyl “Cabbage”, “radish” [135] (Brassica oleracea L. var. italica) isothiocyanate, 2-methyl butyl isothiocyanate, and 3-isopropyl-2-methoxypyrazine Cabbage 2-Propenyl isothiocyanate, methanethiol, dimethyl sulphide, dimethyl trisulphide, ethanol, “Sulphury”, “onion”, “sweet corn” [136,137] (Brassica oleracea L. var. capitate) methyl acetate, ethyl acetate, hexanal, (E)-2-hexenal, and (Z)-3-hexen-1-ol Cauliﬂower 2-Propenyl isothiocyanate, dimethyl trisulphide, dimethyl sulphide, and methanethiol “Sulphur”, “cauliﬂower”, “putrid” [138,139] (Brassica oleracea L. var. botrytis) Carrot α-Pinene, sabinene, myrcene, limonene, β-ocimene, γ-terpinene, p-cymene, terpinolene, “Earthy”, “fruity”, “citrus-like”, “woody”, [134] (Daucus carota L. subsp. sativus) β-caryophyllene, α-humulone, (E)-γ-bisabolene and β-ionone, 3-sec-butyl-2-methoxypyrazine and “sweet” 3-Butylphthalide and 3-butyltetrahydrophthalide (sedanolide), (Z)-3-hexen-1-ol, myrcene, Celery limonene, α-pinene, γ-terpinene, 1,4-cyclohexadiene, 1,5,5-trimethyl-6-methylene-cyclohexene, “Herbal” [140,141] (Apium graveolens L.) 3,7,11,15-tetramethyl-2-hexadecen-1-ol, and α-humulene Cucumber 3-Isopropyl-2-methoxypyrazine, (E, Z)-2,6-nonadienal, and (E)-2-nonenal “Fatty”, “green”, “cucumber” [140,142] (Cucumis sativus L.) Garlic Allicin, S-alk(en)yl-cysteine sulfoxides, di-2-propenyl disulphide, methyl 2-propenyl disulphide, “Ammonia”, “sulphur-like smell” [143] (Allium sativum L.) dimethyl trisulphide, methyl 2-propenyl trisulphide, and di-2-propenyl trisulphide Leek 1-Propanethiol, dipropyl disulphide, dipropyl trisulphide, methyl(E)-propenyl disulphide, and “Onion”, “green” [144,145] (Allium porrum L.) propyl (E)-propenyl disulphide S-alk(en)yl-cysteine sulfoxides, thiopropanal-S-oxide (the lachrymatory factor) Onion 3,4-dimethyl-2,5-dioxo-2,5-dihydrothiophene, propyl methanethiosulfonate, and propyl “Ammonia”, “sulphur-like smell” [144] (Allium cepa L.) propanethiosulfonate Hexanal, (E)-2-heptenal, (E)-2-octenal, 1-hexanol, (Z)-3-hexen-1-ol, 3-alkyl-2-methoxypyrazines, Pea 3-isopropyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine, 3-isobutyl-2-methoxypyrazine, “Green”, “herbal” [146] (Pisum sativum L.) 5-methyl-3-isopropyl-2-methoxypyrazine, and 6-methyl-3-isopropyl-2-methoxypyrazine Pepper (Z)-3-hexenal, 2-heptanone, (Z)-2-hexenal, (E)-2-hexenal, hexanol, (Z)-3-hexanol, (E)-2-hexenol, “Green pea”, “green bell pepper”, “spicy”, [133] (Capsicum annuum L.) and linalool, 2-Isobutyl 3-methoxypyrazine “herbal” Hexanal, cis -3-hexenal and trans -2-hexenal, hexanol, cis -3-hexenol, 1-penten-3-one, Tomato “Green”, “wasabi”, “privet”, “tomato leaf”, 2-isobutylthiazole, 6-methyl-5-hepten-2-one, β-ionone, 3-methylbutanal, 3-methyl butanol, [147,148] (Solanum lycopersicum L.) “fatty”, “grassy” 2-pentenal, acetone, ethanol and fureanol, (Z)-3-hexenal Foods 2021, 10, x FOR PEER REVIEW 14 of 28

Foods 2021, 10, 106 15 of 29

Table 5. The key role of some volatile compounds responsible for the sensory attributes of some vegetable species adapted from Parker et al. [126] and MaarseIn Table[134].5 are some examples of compounds responsible for typical sensory attributes found in vegetables. Vegetables Volatile compound Sensory attributes Table 5. The key roleAlcohols of some volatile compounds responsible for the sensory attributes of some vegetable species adapted Watermelonfrom Parker et al. [(Z,126 ]Z)-3,6-Nonadienol and Maarse [134]. “Fatty”, “soapy”, “cucumber”, “watermelon”, “rind” VegetablesAldehydes Volatile Compound Sensory Attributes Cucumber (E)-2-NonenalAlcohols “Fatty”, “green”, “cucumber” Tomato (Z)-3-Hexenal “Green”,“Fatty”, “fatty”, “soapy”, “grassy” “cucumber”, “watermelon”, Watermelon (Z, Z)-3,6-Nonadienol Lactones “rind” Celery 3-ButylphthalideAldehydes “Herbal” Cucumber (E)-2-nonenal “Fatty”, “green”, “cucumber” TomatoPyrazines (Z)-3-hexenal “Green”, “fatty”, “grassy” Green bell pepper, peas 2-Isobutyl 3-methoxypyrazine “Green pea”, “green bell pepper”, “spicy”, “herbal” Lactones Celery 3-Butylphthalide“Earthy”, “Herbal” “fruity”, “citrus-like”, “spicy”, “woody”, and Carrot 3-Sec-butyl-2-methoxypyrazine Pyrazines “sweet” “Green pea”, “green bell pepper”, “spicy”, Green bell pepper, peasTerpenoids 2-Isobutyl 3-methoxypyrazine Red beet Geosmin “Freshly“herbal” plowed soil”, “earthy” “Earthy”, “fruity”, “citrus-like”, “spicy”, “woody”, Carrot 3-sec-butyl-2-methoxypyrazine Sulphur compounds and “sweet” Asparagus, cabbage Dimethyl sulphideTerpenoids “Sulphury”, “onion”, “sweet corn” TomatoRed beet2-Isobutyl Geosminthiazole “Green”, “Freshly “wasabi”, plowed soil”, “privet”, “earthy” “tomato leaf” Turnip 3-Butenyl-glucosinolateSulphur compounds “Bitter taste and aftertaste” BroccoliAsparagus, cabbage 4-Methylthiobutyl Dimethyl sulphideisothiocyanate “Cabbage”, “Sulphury”, “radish” “onion”, “sweet corn” Tomato 2-Isobutyl thiazole “Green”, “wasabi”, “privet”, “tomato leaf” Onion Turnip Propyl propanethiosulfonate 3-Butenyl-glucosinolate “Roasted “Bitter alliaceous” taste and aftertaste” Radish Broccoli4-Methylthio-3-butenyl-isothiocyanate 4-Methylthiobutyl isothiocyanate “Sharp “Cabbage”, taste”, “mustard/horseradish-like” “radish” Garlic, onionOnion S-alk(en)yl-cysteine Propyl propanethiosulfonate sulfoxides “Ammonia”, “Roasted alliaceous”“sulphur-like smell” Radish 4-Methylthio-3-butenyl-isothiocyanate “Sharp taste”, “mustard/horseradish-like” Garlic, onion S-alk(en)yl-cysteine sulfoxides “Ammonia”, “sulphur-like smell” Branched-chain alcohols, which are a result of amino acid deamination and decar- boxylationBranched-chain [139,149], alcohols, are common which are in a plant result materials. of amino acid (Z, deamination Z)-3,6-Nonadienol and decar- (Figure 11) has beenboxylation described [139,149 as], arehaving common “fatty”, in plant “soapy”, materials. “cucumber”, (Z, Z)-3,6-Nonadienol “watermelon”, (Figure 11) has and “rind” sen- sorybeen attributes, described as havingin watermelon, “fatty”, “soapy”, but also “cucumber”, “boiled “watermelon”, leaf-like” and and “grassy” “rind” sensory attributes in fresh- cutattributes, melon in [150] watermelon, or “muskmelon-like” but also “boiled leaf-like” and “musky” and “grassy” flavors attributes in cantaloupe in fresh-cut [151]. melon [150] or “muskmelon-like” and “musky” ﬂavours in cantaloupe [151].

Figure 11. Chemical structure of (Z, Z)-3,6-nonadienol. Figure 11. Chemical structure of (Z, Z)-3,6-nonadienol. Volatile aldehydes, also a chemical class formed by the lipoxygenase pathway from fattyVolatile acids [139 ,aldehydes,149], are well-known also a chemical for their green class note formed odour. by (E)-2-nonenal the lipoxygenase and (Z)-3- pathway from fattyhexenal acids (Figure [139,149], 12), despite are well-known their different structures,for their green also originate note odour. from different (E)-2-Nonenal fatty and (Z)-3- acids ((E)-2-nonenal, from linoleic acid and (Z)-3-hexenal from linolenic acid) and are de- Hexenalscribed as (Figure presenting 12), other despite sensory their attributes. different “Penetrating”, structures, “waxy” also [150 originate] or “fatty” from [152] different fatty acidscharacteristics ((E)-2-Nonenal, have been linkedfrom tolinoleic (E)-2-nonenal, acid and while, (Z)-3-Hexenal for (Z)-3-hexenal, from “leafy”, linolenic “power- acid) and are describedful”, “strawberry as presenting leaf”, “winey”, other “green sensory leaves”, attribut “apple-like”,es. “Penetrating”, “leaf-like” and “waxy” “cut grass” [150] or “fatty” [152]attributes characteristics have also been have linked. been linked to (E)-2-Nonenal, while, for (Z)-3-Hexenal, “leafy”, “powerful”, “strawberry leaf”, “winey”, “green leaves”, “apple-like”, “leaf-like” and “cut grass” attributes have also been linked.

Figure 12. Chemical structure of (E)-2-Nonenal and (Z)-3-Hexenal.

Foods 2021, 10, x FOR PEER REVIEW 15 of 28

Foods 2021, 10, 106 Figure 5. Structures of monomeric flavan-3-ols. 16 of 29

Sesquiterpene lactones are among the most prevalent and biologically significant classes of secondary metabolites found across the plant kingdom, comprising over 5000 Foods 2021, 10, x FOR PEER REVIEW known compounds, being most common in families such as Cactaceae, Solanaceae, Araceae15 of 28 , Figure 5. Structures of monomeric flavan-3-ols. and the Euphorbiaceae. 3-Butylphthalide (Figure 13) is one of the most known lactones, and besides the “herbal” note associated with it, it is also mainly responsible for the “celery” aromaSesquiterpene [153]. lactones are among the most prevalent and biologically significant Figure 12. Chemical structure of (E)-2-nonenal and (Z)-3-hexenal. classes of secondary metabolites found across the plant kingdom, comprising over 5000

knownSesquiterpene compounds, lactones being are among most thecommon most prevalent in families and biologically such as significantCactaceae classes, Solanaceae, Araceae, of secondaryFigure metabolites 12. Chemical found structure across the of ( plantE)-2-nonenal kingdom, and comprising(Z)-3-hexenal. over 5000 known and the Euphorbiaceae. 3-Butylphthalide (Figure 13) is one of the most known lactones, and compounds, being most common in families such as Cactaceae, Solanaceae, Araceae, and the besidesEuphorbiaceae the. 3-Butylphthalide“herbal” note (Figureassociated 13) is one with of theit, mostit is knownalso mainly lactones, responsible and besides the for the “celery” aroma“herbal” [153] note associated. with it, it is also mainly responsible for the “celery” aroma [153].

Figure 13. Chemical structure of 3-Butylphthalide. Figure 12. Chemical structure of (E)-2-nonenal and (Z)-3-hexenal. Pyrazines are heterocyclic compounds found in a wide variety of foods and are mostly associatedFigure with 13 .nutty Chemical and structure roasty of 3-butylphthalide.flavors, as well as those of green vegetables. 2- Isobutyl 3-methoxypyrazine and 3-Sec-butyl-2-methoxypyrazine (Figure 14) are two well- FigureFigureknown 13. 13. Chemicalpyrazines Chemical structure structurethat ofpresent 3-butylphthalide. of 3-Butylphthalide. low sensory det ection thresholds, making them very important,Pyrazines as they are heterocyclic can be the compounds compounds found respon in a widesible variety for ofthe foods dominating and are mostly aromatic features associatedin severalPyrazines with vegetables nutty are andheterocyclic [154]. roasty ﬂavours, compounds as well as those found of green in a vegetables. wide variety 2-Isobutyl of foods and are mostly3-methoxypyrazine associated and with 3-sec nutty-butyl-2-methoxypyrazine and roasty flavors, (Figure as well 14) areas those two well-known of green vegetables. 2- Isobutylpyrazines 3-methoxypyrazine that present low sensory and detection 3-Sec-butyl-2-methoxypyrazine thresholds, making them very important, (Figure as14) are two well- they can be the compounds responsible for the dominating aromatic features in several knownvegetables pyrazinesFigure [154]. 13. thatChemical present structure low sensory of 3-butylphthalide. detection thresholds, making them very important, as they can be the compounds responsible for the dominating aromatic features in several vegetables [154]. Figure 14. Chemical structure of 2-isobutyl 3-methoxypyrazine and 3-sec-butyl-2-methoxypyrazine.

Figure 14. Chemical structure of 2-Isobutyl 3-methoxypyrazine and 3-Sec-butyl-2-methoxypyrazine.

Figure 14. Chemical structure of 2-Isobutyl 3-methoxypyrazine and 3-sec-butyl-2-methoxypyrazine. The chemical class of terpenoids includes compounds widely distributed in plants The chemical class of terpenoids includes compounds widely distributed in plants Figure 14. Chemicaland structure fruits and of 2-isobutyl can be divided 3-methoxypyrazine into two majo andr 3- groups:sec-butyl-2-methoxypyrazine. monoterpenes and sesquiterpenes andor irregular fruits and canterpenes, be divided which into two are major mostly groups: synthe monoterpenessized in andcatabolic sesquiterpenes reactions or and/or by au- Figureirregular 14. terpenes, Chemical which structure are mostly of 2-Isobutyl synthesised 3-meth in catabolicoxypyrazine reactions and and/or 3-Sec-butyl-2-methoxypyra- by autoxida- zine.tiontoxidation [ 155]. Geosmin [155]. (FigureGeosmin 15) is(Figure an irregular 15) is terpene, an irregular and its major terpene, sensory and attributes, its major as sensory attrib- referredutes, as to, referred are “earthy” to, are and “earthy” “freshly plowed and “freshly soil”. plowed soil”. The chemical class of terpenoids includes compounds widely distributed in plants and fruits and can be divided into two major groups: monoterpenes and sesquiterpenes or irregular terpenes, which are mostly synthesized in catabolic reactions and/or by au- toxidation [155]. Geosmin (Figure 15) is an irregular terpene, and its major sensory attributes, as referred to, are “earthy” and “freshly plowed soil”.

FigureFigure 15. 15.Chemical Chemical structure structure of geosmin. of geosmin.

Sulphur-containing compounds (Figure 16) are synthesized from methionine and cysteine and can be emitted due to an increased accumulation of free methionine. They are key trace volatiles and are a major factor in the sensory properties of fruits and vege- Figuretables 15.[156]. Chemical structure of geosmin.

Foods 2021, 10, 106 17 of 29

Sulphur-containing compounds (Figure 16) are synthesised from methionine and cysteine and can be emitted due to an increased accumulation of free methionine. They are key trace volatiles and are a major factor in the sensory properties of fruits and vegetables [156]. Foods 2021, 10, x FOR PEER REVIEW 16 of 28

Figure 16. Chemical structure of sulphur-containing volatile compounds. Figure 16. Chemical structure of sulphur-containing volatile compounds. FigureTheThe formation16. formation Chemical of of structure volatile volatile of andand sulphur-containing nonvolatilenonvolatile co compoundsmpounds volatile compounds. is is diverse, diverse, due due to to the the multitude multi- tudeof molecules of molecules that that convey convey flavor. ﬂavour. In general, In general, these these molecules molecules are synthesized are synthesised from from terpe- terpenoid,noid, apocarotenoid, apocarotenoid, and and lipoxygenase lipoxygenase pathways pathways and and are arederived derived from from amino amino and and fatty fattyacids acids [139,149] [139,149 (Figure] (Figure 17). 17 ).

Figure 17. The principal plantFigure volatile 17. compounds The principal are plant derived volatile from compounds four biosynthetic are derived classes from of precursors:four biosynthetic terpenoids, classes of fatty acid catabolites, aroma, andprecursors: amino acid terpenoids, derived products.fatty acid Manycatabolites, of these aroma, products and amino are made acid more derived lipophilic products. (storage Many of in membranes or oil bodies) beforethese theirproducts release are by made removing more orlipophilic masking (storage hydrophilic in membranes functional or groups oil bodies) through before reduction, their release by removing or masking hydrophilic functional groups through reduction, methylation, or acyla- methylation, or acylation reactions. Adapted from Baldwin et al. [157]. tion reactions. Adapted from Baldwin et al. [157]. Although many of the volatile and nonvolatile compounds responsible for aromatic featuresAlthough have been many identiﬁed, of the volatile many and of their nonvol biochemistryatile compounds pathways responsible are still for not aromatic well explained.features have Still, severalbeen identified, metabolic many pathways of thei arer biochemistry involved in the pathways biosynthesis are still of compounds not well ex- responsibleplained. Still, for theseveral aromatic metabolic features pathways and taste are in involved vegetables. in Manythe biosynthesis volatile compounds of compounds are responsible for the aromatic features and taste in vegetables. Many volatile compounds are synthesized from fatty acid, amino acid, and carotenoid pathways [130,158], others from isoprenoid substrates. However, it is well-known that primary metabolism is fundamental for the formation of nonvolatile compounds, which also contribute to the aromatic features and taste of vegetables [158] (Figure 18). Among these are sugars, organic acids,

Foods 2021, 10, 106 18 of 29

synthesised from fatty acid, amino acid, and carotenoid pathways [130,158], others from Foods 2021, 10, x FOR PEER REVIEW 17 of 28 isoprenoid substrates. However, it is well-known that primary metabolism is fundamental for the formation of nonvolatile compounds, which also contribute to the aromatic features and taste of vegetables [158] (Figure 18). Among these are sugars, organic acids, free freeamino amino acids, acids, provitamins, provitamins, minerals, minerals, and saltsand salts [159 ].[159]. For example,For example, sweetness sweetness is determined is deter- minedby the by concentrations the concentrations of the of predominant the predominant sugars, sugars, while while sourness sourness is determined is determined by theby theconcentrations concentrations of theof the predominant predominant organic organic acids acids [160 [160].].

Figure 18. Generalized pathways for the synthesis of some nonvolatile compounds present in plants. Figure 18. Generalized pathways for the synthesis of some nonvolatile compounds present in plants.Adapted Adapted from Ncube from Ncube and Staden and Staden [161]. [161]. In tomato, its characteristic sweet-sour taste is due to a combination of the sugars In tomato, its characteristic sweet-sour taste is due to a combination of the sugars and and organic acids, and positive correlations between perceived sweetness, reducing sugar organic acids, and positive correlations between perceived sweetness, reducing sugar con- content, and soluble solids have been found [162]. Therefore, to define what compounds tent, and soluble solids have been found [162]. Therefore, to define what compounds are are more critical to flavour is more complex than expected. Moreover, when vegetables are more critical to flavor is more complex than expected. Moreover, when vegetables are harvested, a catabolic process starts due to the disruption of plant tissues, affecting their harvested, a catabolic process starts due to the disruption of plant tissues, affecting their aroma and transforming their key flavours into different compounds. Some of them may aroma and transforming their key flavors into different compounds. Some of them may even turn into a new biologically active compound. For example, in brassica vegetables, even turn into a new biologically active compound. For example, in brassica vegetables, operations such as cutting, chewing, and cooking have an uncontrolled effect on volatile operations such as cutting, chewing, and cooking have an uncontrolled effect on volatile compounds, due to the mixture of enzymes. The brassica vegetables’ typical odours and compounds,tastes are mainly due to due the to mixture the presence of enzymes. of glucosinolates, The brassica which vegetabl whenes’ in contacttypical withodors the and en- tasteszyme are myrosinase mainly due (EC to 3.2.1.147, the presence thioglucoside of glucosinolates, glucohydrolase) which hydrolysewhen in contact into new with groups the enzymeof breakdown myrosinase products (EC such3.2.1.147, as isothiocyanates, thioglucoside glucohydrolase) organic cyanides, hydrolyze oxazolidinethiones, into new groupsand thiocyanate of breakdown [162 products], affecting such their as isothiocyana aroma and transformingtes, organic cyanides, their key oxazolidinethi- flavour into a ones,different and one.thiocyanate A similar [162], situation affecting occurs their with aromaAllium andspecies, transforming such as their onion, key shallot, flavor garlic, into aleek, different and others,one. A havesimilar in situation common occurs the presence with Allium of the species, sulphur-based such as Sonion,-alk(en)ylcysteine shallot, garlic,sulfoxide leek, and (alliin, others, I) inhave their in composition.common the presen In damagedce of the or sulfur-based disrupted tissue S-alk(en)ylcysteine transformation sulfoxideinto several (alliin, other I) compounds,in their composition. via alliinase In occurreddamaged [ 163or disrupte]. The initiald tissue hydrolysis transformation products intoare ammonia,several other pyruvate, compounds, and an via alk(en)ylthiosulphinate alliinase occurred [163]. (allicin, The initial II), andhydrolysis can undergo products fur- arether ammonia, nonenzymatic pyruvate, reactions and an to alk(en)ylthiosulphinate yield a variety of compounds (allicin, suchII), and as can thiosulphate undergo fur- [III] therand nonenzymatic di- and trisulphides reactions [IV] to [146 yield], which a variet givesy of tocompoundsAllium species such theiras thiosulfate typical odour [III] and of a di-sulphur-like and trisulphides smell. [IV] [146], which gives to Allium species their typical odor of a sulfur- like smell. Although most of such compounds are related to odor and flavor, some of them are also involved in important biochemical activities. Epidemiological studies have shown

Foods 2021, 10, 106 19 of 29

Although most of such compounds are related to odour and flavour, some of them are also involved in important biochemical activities. Epidemiological studies have shown that glucosinolate hydrolysis products (responsible for the bitterness and mustard/horseradish- like flavours) may act as an anticarcinogen agents and can exert antibacterial and antifungal activities against diverse human and plant pathogens [164]. Recently, allicin, a derived compound from alk(en)ylcysteine sulfoxide in Allium species, showed antimicrobial and anticarcinogenic activities [165,166]. Compounds such as lycopene and carotene, largely present in tomato, carrot, and spinach, have been associated with anti-inflammatory properties [167].

3.2. MAP Volatile Compounds Responsible for Aromatic Features Plants provide multiple ranges of aromatic features well-noticed by the most sensitive human senses—taste, and odour [168]. Over time, many plant species have been used to produce foods and medical or herbal formulations [169]. The use of MAPs began as an unselective wild-harvesting of plants, moving into a selective collection and then to the cultivation of the most useful. From ancient times to the present day, plants have been used as medicines and food preservers [170]. Nowadays, their cultivation, pharmacognosy, phytochemistry, biology, conservation, and sustainable use are matters of interest [171]. MAPs yield a wide variety of natural compounds, produced and stored in glands located in different parts of the plant: leaves, flowers, fruits, seeds, barks, and roots [172,173]. These natural compounds, most of which are essential oils, are volatile at room temperature, and important for plant adaptation and survival—namely as pollinator attractants, as herbivores restraints, or as a defence against pathogenic microorganisms. Because of their biological activities, they are also important to Man in both commercial and industrial resources—namely, in traditional medicine [172], which also provides raw materials for use in pharmaceuticals, cosmetics, food, and chemical industries [173]. What are the MAPs? According to Maiti and Geetha [174], MAPs are plants that provide “medicines” to humans that prevent disease, maintain health, or cure illnesses; “let food be your medicine”, attributed to Hippocrates, 460–377 B.C., is again a popular concept. New designations have emerged to classify the beneficial effects of the use of some plants or plant parts and products. According to Barata et al. [172], MAPs can be divided into four groups, based on their final usage: raw materials for essential oil extraction, which is the major use of MAPs around the world; spices, nonleafy parts of plants used as flavouring or seasoning; herbs, leafy or soft flowering parts of the plant used as flavouring or seasoning; miscellaneous group, MAPs used in different ways. The International Union for Conservation of Nature and the World Wildlife Fund estimated that about 50,000–80,000 flowering plant species are used in medicinal formulations across the world. Among these, only 1 to 10% has been studied chemically and pharmacologically for their potential value [175]. MAPs contain a wide variety of bioactive secondary metabolites, such as essential oils, alkaloids, phenolics (such as flavonoids), steroids, terpenes, sesquiterpenes, diterpenes, and saponins [176], that find uses in several perfumeries, flavourings, and pharmaceutical compounds [177]. Many secondary metabolites include aroma substances, and phenolic compounds or their oxygen-substituted derivatives such as tannins [178], and many of these compounds have anti-inflammatory and antioxidant properties. Plant secondary metabolites are characterised as exhibiting chemical polymorphism, which causes the occurrence of several chemotypes within the same species [179]. The chemotypes are of extreme importance when considering the safety, quality, and efficacy of herbal products derived from MAPs. There are numerous cases of plant species showing a great variety of chemotypes. The genus Thymus shows many examples since many Thymus species are chemically heterogeneous. Thymus vulgaris is among the most popular plants having chemotypes. Six different chemotypes are known, depending on the main component of the essential oil: thymol, carvacrol, linalool, geraniol, borneol, sabinete hydrate, and multiple component chemotypes [180]. Foods 2021, 10, 106 20 of 29

FoodsFoods 2021 2021, ,10 10, ,x x FOR FOR PEER PEER REVIEW REVIEW 1919 of of 28 28 Foods Foods 20212021,,, 1010,,, xxx FORFORFOR PEERPEERPEER REVIEWREVIEWREVIEW Table6 summarises some important MAPs and their main volatile compounds.1919 ofof 2828 Re-

garding the data presented in this table, a different type of compound is responsible for the aromatic features of MAPs. For example, Lee et al. [181] identify a high content of linalool,linalool, methylmethyl cinnamate,cinnamate, estragole,estragole, eugenol,eugenol, andand 1,8-cineole1,8-cineole compoundscompounds inin basilbasil culti-culti- linalool,linalool,linalool, methylmethyl methylcinnamate,cinnamate, cinnamate, estragole,estragole, estragole, eugenol,eugenol, eugenol, andand 1,8-cineole1,8-cineole and 1,8-cineole compoundscompounds compounds inin basilbasil inculti-culti- basil culti- varsvars andand reportedreported thatthat thesethese compoundscompounds werewere responsibleresponsible forfor thethe typicaltypical aromaaroma ofof basilbasil varsvars andandvars reportedreported and reported thatthat thesethese that compoundscompounds these compounds werewere responsibleresponsible were responsible forfor thethe typical fortypical the typicalaromaaroma of aromaof basilbasilof basil perceivedperceived byby consumers.consumers. SimilarSimilar resultsresults werewere presentedpresented byby ShahwarShahwar etet al.al. [182],[182], whowho re-re- perceivedperceivedperceived byby consumers.consumers. by consumers. SimilarSimilar resultsresults Similar werewere results presentedpresented were presented byby ShahwarShahwar by etet Shahwar al.al. [182],[182], et whowho al. [ re-182re- ], who portedported thatthat thethe typicaltypical aromaaroma ofof coriandercoriander isis duedue toto aa mixturemixture ofof differentdifferent compoundscompounds inin portedported thatreportedthat thethe typicaltypical that the aromaaroma typical ofof aroma coriandercoriander of coriander isis duedue toto is aa duemixturemixture to a mixtureofof differentdifferent of different compoundscompounds compounds inin in whichwhich decenaldecenal andand relatedrelated compoundscompounds (Table(Table 6)6) assumeassume aa highhigh preponderance.preponderance. SeveralSeveral whichwhich decenaldecenalwhich decenal andand relatedrelated and relatedcompoundscompounds compounds (Table(Table 6)6) (Table assumeassume6) assume aa highhigh a preponderance.preponderance. high preponderance. SeveralSeveral Several otherother authorsauthors [181–191][181–191] havehave reportedreported thatthat thethe typicaltypical aromaticaromatic featuresfeatures exhibitedexhibited byby otherother authorsauthorsother authors [181–191][181–191] [181 have–have191] reported havereported reported thatthat thatthethe thetypicaltypical typical aromaticaromatic aromatic featuresfeatures features exhibitedexhibited exhibited byby by MAPs MAPsMAPs areare a a result result ofof aa combinedcombinedcombined effect effecteffect of ofof several severalseveral compounds compoundscompounds rather ratherrather than thanthan a a singlea singlesingle compound, com-com- as MAPsMAPs areare aa resultresult ofof aa combinedcombined effecteffect ofof severalseveral compoundscompounds ratherrather thanthan aa singlesingle com-compound,pound, shown asas shownshown by by Kizhakkayilby KizhakkayilKizhakkayil and andand Sasikumar SasikuSasikumarmar [185 [185][185]] for forfor ginger. ginger.ginger. These TheseThese authors authorsauthors reported reportedreported that the pound,pound, asas shownshown byby KizhakkayilKizhakkayil andand SasikuSasikumarmar [185][185] forfor ginger.ginger. TheseThese authorsauthors reportedreported thatthat the thetypical typical typical “spicy” “spicy” “spicy” and and and “fresh” “fresh” “fresh” aromas aromas aromas exhibited exhi exhibitedbited by by by ginger ginger ginger is is is due due due to to to the the the simultaneous simultaneous simultaneous presence thatthat thethe typicaltypical “spicy”“spicy” andand “fresh”“fresh” aromasaromas exhiexhibitedbited byby gingerginger isis duedue toto thethe simultaneoussimultaneous presencepresenceof ofof different differentdifferent compounds compoundscompounds such such such as as zingiberene,as zingzingiberene,iberene, 6-gingerol, 6-gingerol,6-gingerol, 8-gingerol, 8-gingerol,8-gingerol, 10-gingerol, 10-gingerol, 10-gingerol, 6-shogaol, presencepresence ofof differentdifferent compoundscompounds suchsuch asas zingzingiberene,iberene, 6-gingerol,6-gingerol, 8-gingerol,8-gingerol, 10-gingerol,10-gingerol, 6-shogaol,6-shogaol,8-shogaol, 8-shogaol,8-shogaol, geranial, geranial,geranial, and andand neral. neral.neral. These TheseThese compounds, compounds,compounds, even eveneven in lower inin lowerlower amounts, amounts,amounts, are are criticalare for 6-shogaol,6-shogaol, 8-shogaol,8-shogaol, geranial,geranial, andand neral.neral. TheseThese compounds,compounds, eveneven inin lowerlower amounts,amounts, areare criticalcritical for thefor the the consumer consumer consumer to perceiveto to perceive perceive the the the typical typi typicalcal aroma aroma aroma of of ginger,of ginger, ginger, all all ofall of themof them them are are are important important important to deﬁne criticalcritical forfor thethe consumerconsumer toto perceiveperceive thethe typitypicalcal aromaaroma ofof ginger,ginger, allall ofof themthem areare importantimportant toto definedefinethe thethe ginger gingerginger “bouquet”. “bouquet”.“bouquet”. toto definedefine thethe gingerginger “bouquet”.“bouquet”. TableTableTable 6.6. 6.KeyKeyKey volatilevolatile volatile compoundscompounds compounds presentpresent present inin in somesome some medicinalmedicinal medicinal andand ar aromaticaromaticomatic plantsplants (MAPs).(MAPs). InInIn bold boldbold are areare the thethemajor majormajor volatile volatilevolatile compounds of TableTable 6.6. KeyKey volatilevolatile compoundscompounds presentpresent inin somesome medicinalmedicinal andand araromaticomatic plantsplants (MAPs).(MAPs). InIn boldbold areare thethe majormajor volatilevolatile compoundscompoundseach MAP. of of The each each names MAP. MAP. of The The the names names compounds of of the the incompound compound bold ares thoses in in bold bold represented are are those those inrepresented represented the ﬁgures. in in the the figures. figures. compoundscompounds ofof eacheach MAP.MAP. TheThe namesnames ofof thethe compoundcompoundss inin boldbold areare thosethose representedrepresented inin thethe figures.figures. Chemical Structure of Ma- MAP Main Volatile Compounds ChemicalChemicalChemical Structure Structure Structure of of of Major Ma- Ma- Ref. MAPMAP MAPMainMain Main Volatile Volatile Volatile Compounds Compounds Compounds Chemical Structure of Ma- Ref.Ref. Ref. MAPMAP MainMain VolatileVolatile CompoundsCompounds jorjorVolatile Volatile Volatile Compounds Compounds Compounds Ref.Ref. jorjor VolatileVolatile CompoundsCompounds

BasilBasil BasilBasil Basil LinaloolLinalool, ,methyl methylLinalool cinnamate, cinnamate,, methyl estragole, cinnamate,estragole, eugenol, eugenol, estragole, and and eugenol, 1,8-cineole 1,8-cineole and [181][181] ((OcimumOcimum basilicum basilicum L.) L.) LinaloolLinalool,, methylmethyl cinnamate,cinnamate, estragole,estragole, eugenol,eugenol, andand 1,8-cineole1,8-cineole [181][181] [ 181] ((OcimumOcimum basilicum(basilicumOcimum L.) basilicumL.) L.) 1,8-cineole

(E)-2-Decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2- Coriander (E)-2-Decenal(E)-2-Decenal(E)-2-Decenal(E,,)-2-Decenal , linalool, linalool,linalool, (E)-2-dodecenal (E)-2-dodecenal(E)-2-dodecenal, linalool, (E)-2-dodecenal,,, , (E)-2-tetradecenal, (E)-2-tetradecenal,(E)-2-tetradecenal, 2- 2-2- CorianderCoriander (E)-2-Decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2- CorianderCorianderCoriander decen-1-ol,decen-1-ol, (E)-2-undecenal, ((E)-2-undecenal,E)-2-tetradecenal, dodecanal, dodecanal, 2-decen-1-ol, (E)-2-tridecenal, (E)-2-tridecenal, (E)-2-undecenal, (E)-2- (E)-2- [182][182] ((CoriandrumCoriandrum sativum sativum L.) L.) decen-1-ol,decen-1-ol, (E)-2-undecenal,(E)-2-undecenal, dodecanal,dodecanal, (E)-2-tridecenal,(E)-2-tridecenal, (E)-2-(E)-2- [182][182] [ 182] ((CoriandrumCoriandrum(Coriandrum sativumsativum L.)L.) sativum hexadecenal,hexadecenal,L.) dodecanal, pentadecenal, pentadecenal, (E)-2-tridecenal, and and α α-pinene-pinene (E )-2-hexadecenal, hexadecenal,hexadecenal, pentadecenal,pentadecenal, andand αα-pinene-pinene pentadecenal, and α-pinene FennelFennel FennelFennel Fennel transtrans-Anethole-Anetholetrans, ,estragole, estragole,-Anethole fenchone fenchone, estragole,, ,and and fenchone, 1-octen-3-ol 1-octen-3-ol and [183][183] ((FoeniculumFoeniculum vulgare vulgare (Mill.) (Mill.) transtrans-Anethole-Anethole,, estragole,estragole, fenchonefenchone,, andand 1-octen-3-ol1-octen-3-ol [183][183] [ 183] ((FoeniculumFoeniculum(Foeniculum vulgarevulgare (Mill.)(Mill.) vulgare (Mill.) 1-octen-3-ol

ZingibereneZingibereneZingiberene, ,6-gingerol, 6-gingerol, ,8-gingerol, 8-gingerol, 6-gingerol, 10-gingerol, 8-gingerol,10-gingerol, 10-gingerol,6-shogaol, 6-shogaol, 8- 8- ZingibereneZingiberene,, 6-gingerol,6-gingerol, 8-gingerol,8-gingerol, 10-gingerol,10-gingerol, 6-shogaol,6-shogaol, 8-8- GingerGinger Ginger shogaol,shogaol, 10-shogaol, 10-shogaol,6-shogaol, geranial, geranial, 8-shogaol, neral, neral, 10-shogaol, 1,8-cineole, 1,8-cineole, geranial, β β-bisabolene,-bisabolene, neral, β β-- GingerGinger shogaol,shogaol, 10-shogaol,10-shogaol, geranial,geranial, neral,neral, 1,8-cineole,1,8-cineole, ββ-bisabolene,-bisabolene, ββ-- [184,185][184,185][184 , 185] ((ZingiberZingiber officinale (officinaleZingiber Rosc.) Rosc.) ofﬁcinale sesquiphellandrene,sesquiphellandrene,Rosc.) 1,8-cineole, (E)(E)- (E)(E)-β-bisabolene,αα-farnesene,-farnesene,β-sesquiphellandrene, viridiflorol, viridiflorol, and and (E)(E)-far- (E)(E)-far- [184,185][184,185] ((ZingiberZingiber officinaleofficinale Rosc.)Rosc.) sesquiphellandrene,sesquiphellandrene,α (E)(E)-(E)(E)-αα-farnesene,-farnesene, viridiflorol,viridiflorol, andand (E)(E)-far-(E)(E)-far- nesalnesal (E)(E)- -farnesene, viridiﬂorol, and (E)(E)-farnesal nesalnesal

LavenderLavender Lavender LavenderLavender ((LavandulaLavandula(Lavandula angustifolia angustifolia angustifolia 1,8-Cineole1,8-Cineole,1,8-Cineole ,camphor camphor and and, camphor borneol borneol and borneol [186][186] [ 186 ] ((LavandulaLavandula angustifoliaangustifolia 1,8-Cineole1,8-Cineole,, camphorcamphor andand borneolborneol [186][186] Mill.)Mill.) Mill.) Mill.)Mill.)

MelissaMelissa Melissa GeranialGeranial, ,neral, neral,Geranial alloaromadendrene, alloaromadendrene,, neral, alloaromadendrene, geranyl geranyl acetate, acetate, geranyl 6-methyl-5- 6-methyl-5- acetate, MelissaMelissa GeranialGeranial,, neral,neral, alloaromadendrene,alloaromadendrene, geranylgeranyl acetate,acetate, 6-methyl-5-6-methyl-5- [187][187] [ 187 ] (Melissa officinalis(Melissa L.) ofﬁcinalis hepten-2-one,L.) 6-methyl-5-hepten-2-one, and β-caryophyllene and β-caryophyllene [187][187] (((MelissaMelissa officinalis officinalis L.) L.) hepten-2-one,hepten-2-one, and and β β-caryophyllene-caryophyllene-caryophyllene [187] (Melissa officinalis L.) hepten-2-one, and β-caryophyllene

Oregano Sabinene, 1,8-cineole,Sabinene, caryophyllene 1,8-cineole, caryophyllene oxide, (E)-β-caryophyllene, oxide, p- OreganoOregano Oregano SabineneSabinene,, , 1,8-cineole, 1,8-cineole,1,8-cineole, caryophyllene caryophyllenecaryophyllene oxide, oxide,oxide, (E)- (E)-(E)-ββ-caryophyllene,-caryophyllene,-caryophyllene, p p--- OreganoOregano SabineneSabinene,, 1,8-cineole,1,8-cineole,(E)-β-caryophyllene, caryophyllenecaryophyllenep-cymene, oxide,oxide, (E)-α(E)--terpineol,ββ-caryophyllene,-caryophyllene, and pp-- [188][188] [ 188 ] ((OriganumOriganum(Origanum vulgare vulgare L L.). vulgare) cymene,cymene,L.) α α-terpineol,-terpineol, and and germacrene germacrene D D [188][188] ((OriganumOriganum vulgarevulgare LL..)) cymene,cymene, αα-terpineol,-terpineol,germacrene andand D germacrenegermacrene DD

αα-Pinene-Pinene, ,sabinene, sabinene, myrcene, myrcene, β β-pinene,-pinene, cis cis-3-hexenyl-3-hexenyl acetate, acetate, α α-- ParsleyParsley αα-Pinene-Pinene,, sabinene,sabinene, myrcene,myrcene, ββ-pinene,-pinene, ciscis-3-hexenyl-3-hexenyl acetate,acetate, αα-- ParsleyParsley phellandrene,phellandrene, p p-cymene,-cymene, limonene, limonene, β β-phellandrene,-phellandrene, trans trans--ββ-- ((PetroselinumPetroselinum crispum crispum phellandrene,phellandrene, pp-cymene,-cymene, limonene,limonene, ββ-phellandrene,-phellandrene, transtrans--ββ-- [189][189] ((PetroselinumPetroselinum crispumcrispum ocimene,ocimene, γ γ-terpinene,-terpinene, terpinolene, terpinolene, 1,3,8-p-menthatriene, 1,3,8-p-menthatriene, α α-terpin--terpin- [189][189] (Mill(Mill.).) Nym. Nym. Ex Ex A.W.Hill A.W.Hill ocimene,ocimene, γγ-terpinene,-terpinene, terpinolene,terpinolene, 1,3,8-p-menthatriene,1,3,8-p-menthatriene, αα-terpin--terpin- (Mill(Mill..)) Nym.Nym. ExEx A.W.HillA.W.Hill eol,eol, trans trans--ββ-caryophylle,-caryophylle, germacrene-D, germacrene-D, nerolidol, nerolidol, and and myristcin myristcin eol,eol, transtrans--ββ-caryophylle,-caryophylle, germacrene-D,germacrene-D, nerolidol,nerolidol, andand myristcinmyristcin

Foods 2021, 10, x FOR PEER REVIEW 19 of 28

linalool, methyl cinnamate, estragole, eugenol, and 1,8-cineole compounds in basil cultivars and reported that these compounds were responsible for the typical aroma of basil perceived by consumers. Similar results were presented by Shahwar et al. [182], who reported that the typical aroma of coriander is due to a mixture of different compounds in which decenal and related compounds (Table 6) assume a high preponderance. Several other authors [181–191] have reported that the typical aromatic features exhibited by MAPs are a result of a combined effect of several compounds rather than a single compound, as shown by Kizhakkayil and Sasikumar [185] for ginger. These authors reported that the typical “spicy” and “fresh” aromas exhibited by ginger is due to the simultaneous presence of different compounds such as zingiberene, 6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, geranial, and neral. These compounds, even in lower amounts, are critical for the consumer to perceive the typical aroma of ginger, all of them are important to define the ginger “bouquet”.

Table 6. Key volatile compounds present in some medicinal and aromatic plants (MAPs). In bold are the major volatile compounds of each MAP. The names of the compounds in bold are those represented in the figures.

Chemical Structure of Ma- MAP Main Volatile Compounds Ref. jor Volatile Compounds

Basil Linalool, methyl cinnamate, estragole, eugenol, and 1,8-cineole [181] (Ocimum basilicum L.)

(E)-2-Decenal, linalool, (E)-2-dodecenal, (E)-2-tetradecenal, 2- Coriander decen-1-ol, (E)-2-undecenal, dodecanal, (E)-2-tridecenal, (E)-2- [182] (Coriandrum sativum L.) hexadecenal, pentadecenal, and α-pinene

Fennel trans-Anethole, estragole, fenchone, and 1-octen-3-ol [183] (Foeniculum vulgare (Mill.)

Zingiberene, 6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8- Ginger shogaol, 10-shogaol, geranial, neral, 1,8-cineole, β-bisabolene, β- [184,185] (Zingiber officinale Rosc.) sesquiphellandrene, (E)(E)-α-farnesene, viridiflorol, and (E)(E)-farnesal

Lavender (Lavandula angustifolia 1,8-Cineole, camphor and borneol [186] Mill.)

Melissa Geranial, neral, alloaromadendrene, geranyl acetate, 6-methyl-5- Foods 2021, 10, 106 [187] 21 of 29 (Melissa officinalis L.) hepten-2-one, and β-caryophyllene

Table 6. Cont. Oregano Sabinene, 1,8-cineole, caryophyllene oxide, (E)-β-caryophyllene, p- [188] (Origanum vulgare L.) cymene, α-terpineol, and germacrene D Chemical Structure of Major MAP Main Volatile Compounds Ref. Volatile Compounds

α-Pinene, sabinene, myrcene, β-pinene, α-Pinene, sabinene,cis-3-hexenyl myrcene, acetate, β-pinene,α-phellandrene, cis-3-hexenylp-cymene, acetate, α- Parsley Parsley phellandrene,limonene, p-cymene,β-phellandrene, limonene, β-phellandrene,trans-β-ocimene, trans-β- (Petroselinum(Petroselinum crispum crispum [189] [ 189] Foods 2021, 10, x FOR PEER REVIEWocimene, γ-terpinene,γ-terpinene, terpinolene, terpinolene, 1,3,8-p-menthatriene, 1,3,8-p-menthatriene, α-terpin- 20 of 28 (Mill .) Nym.(Mill.) Ex A.W.Hill Nym. Ex A.W.Hill Foods 2021,, 10,, xx FORFOR PEERPEER REVIEWREVIEW α-terpineol, trans-β-caryophylle, germacrene-D, 20 of 28 Foods 2021, 10, x FOR PEER REVIEWeol, trans -β-caryophylle, germacrene-D, nerolidol, and myristcin 20 of 28 nerolidol, and myristcin Santene, camphene, β-pinene, myrcene, Santene, camphene,cis-3-hexenyl β-pinene, acetate, myrcene,p-cymene, cis-3-hexenylα-terpinene, acetate, p-cy- PeppermintPeppermint Santenemene, α-terpinene,,, camphene,camphene,limonene, limonene, β-pinene,trans-β -ocimene,trans myrcene,-β-ocimene,γ cis-terpinene,-3-hexenyl γ-terpinene, acetate, trans p-cy-- Peppermint mene, α-terpinene, limonene, trans-β-ocimene, γ-terpinene, trans- [189] [ 189] Peppermint(Mentha x( Menthapiperita L.)x piperita mene,sabineneL.) α-terpinene, hydrate,trans-sabinene nonanal, limonene, hydrate,linalool, trans-β nonanal,cis-ocimene,-limonene linalool, γ-terpinene, oxide, trans trans-limo-- [189] ( Mentha x piperita L.) sabinene hydrate, nonanal, linalool, cis-limonene oxide, trans-limo- [189] (Mentha xx piperita L.) sabinenenene oxide, hydrate, cisand-limonene cis nonanal,-p-mentha-2,8-dien-1-ol oxide, linalool,trans cis-limonene-limonene oxide, oxide, and trans-limonene oxide, andcis-p -mentha-2,8-dien-1-olcis-p-mentha-2,8-dien-1-ol nene oxide, and cis-p-mentha-2,8-dien-1-ol Rosemary α-Pinene, myrcene, 1,8 cineole, camphor, caryophyllene, α-hu- α-Pinene, myrcene, 1,8 cineole, camphor, [190] Rosemary(RosmarinusRosemary officinalis L.) αmulene,-Pinene nerolidol,,, myrcene,myrcene, spathulenol, 1,81,8 cineole,cineole, camphor,andcamphor, rosmarinic caryophyllene,caryophyllene, acid α-hu- Rosemary α-Pinene, myrcene,caryophyllene, 1,8 cineole,α-humulene, camphor, nerolidol, caryophyllene, spathulenol, α-hu- [190] [ 190] (Rosmarinus(Rosmarinus officinalis L ofﬁcinalis..) mulene,L.) nerolidol, spathulenol, and rosmarinic acid [190] (Rosmarinus officinalis L.) mulene, nerolidol,and rosmarinic spathulenol, acid and rosmarinic acid

Thymus Thymol, carvacrol, linalool, geraniol, borneol, and sabinete hydrate [180] Thymus(Thymus vulgarisThymus L.) Thymol, carvacrol, linalool, geraniol, borneol, and Thymol,, carvacrol,carvacrol, linalool,linalool, geraniol,geraniol, borneol, and sabinete hydrate [180] [180] (Thymus vulgaris(Thymus L.) vulgaris L.) sabinete hydrate

Sage α-Thujone, 1,8 cineole, β-caryophyllene, α-humulene, α-pinene, β- α-Thujone, 1,8 cineole, β-caryophyllene, [191] Sage(Salvia officinalisSage L.) αthujone,-Thujone β-pinene,,, 1,81,8 cineole,cineole, camphene, β-caryophyllene, camphor, and α-humulene, p-cymene α-pinene, β- α-humulene, α-pinene, β-thujone, β-pinene, [191] [ 191] (Salvia officinalis(Salvia L ofﬁcinalis..) L.)thujone, β-pinene, camphene, camphor, andand p-cymene camphene, camphor, and p-cymene

For better exploitation of any MAP species, it is necessary to evaluate the genetic stabilityFor ofbetter their exploitation populations, of i.e., any whether MAP species,such populations it is necessary continue to evaluateto produce the the genetic same For betterFor exploitation better exploitation of any MAP of any species, MAP species, it is necessary it is necessary to evaluate to evaluate the genetic the genetic stabilitycharacteristic of their products populations, after beingi.e., whether transplanted such populations to and grown continue in habitats to produce with thedifferent same stabilitystability of their ofpopulations, their populations, i.e., whether i.e., whether such populations such populations continue continue to produce to produce the same the same characteristic products after being transplanted to and grown in habitats with different characteristicedaphoclimaticcharacteristic products conditions. products after In being all, after for transplanted beingeach species, transplanted to it and is crucial grown to and to ingrownperform habitats in a habitats detailedwith different withstudy, different edaphoclimatic conditions. In all, for each species, it is crucial to perform a detailed study, edaphoclimaticwhich addresses,edaphoclimatic conditions. for instance, conditions. In all, the for Ininfluence each all, for species, each of seasonal species,it is crucial and it is to crucialgeographic perform to perform a detailedvariations a detailed study, and study, which addresses, for instance, the influence of seasonal and geographic variations and whichlocal environmental addresses,which addresses, for conditions. instance, for instance, the The influence theresults influence ob oftained seasonal of seasonal will and provide andgeographic geographic the scientific variations variations basis and for and local local environmental conditions. The results obtained will provide the scientific basis for localthe selection environmentalenvironmental and cultivation conditions. conditions. of species The The results showin results obgtained obtained better will qualities, will provide provide thus the bringing thescientific scientific some basis basis eco- for for the the selection and cultivation of species showing better qualities, thus bringing some eco- thenomic selection andselection social and and benefitscultivation cultivation for oflocal species of growers. species showin showing g better better qualities, qualities, thus thus bringing bringing some some eco- economic nomic and social benefits for local growers. nomic andand social social benefits benefits for for local local growers. growers. 3.3. Advances in Aromatic Features and Future Research Perspectives 3.3. Advances in Aromatic Features and Future Research Perspectives 3.3. AdvancesFrom3.3. the Advances in aromatic Aromatic in Aromaticfeatures Features Features perspective,and Future and Research Future the actual Research Perspectives challenges Perspectives in research are multifold: From(a) overcome theFrom aromatic the the aromatic crop features defects; features perspective, (b) perspective,refinement the actual of the aroma actual challenges deviations; challenges in research (c) in researchmodulate are multi- are vol- multifold: fold:atile (a)and(a) overcome nonvolatile overcome the the compounds’crop crop defects; defects; biosynthes(b) (b)refin refinementementes to of produce aroma of aroma deviations; high-potency deviations; (c) modulate (c)aromatic modulate vol-fea- volatile atiletures; and (d)and nonvolatileincrease nonvolatile the compounds’accuracy compounds’ of aromaticbiosynthes biosyntheses featureses to to produce producesignature; high-potency (e) understand aromaticaromatic how features;pre-fea- (d) tures;harvest (d)increase and increase postharvest the the accuracy accuracy factors of aromaticcanof aromatic affect featuresvegetable features signature; and signature; MAP (e) aromatic understand(e) understand features how how or preharvest tastes. pre- and harvestThe flavor postharvestand is postharvest the result factors of factors a cancomplex affect can affect metabolic vegetable vegetable andnetwork MAPand thatMAP aromatic can aromatic be features influenced features or tastes. by or several tastes. The flavour Thefactors, flavor issuch the is the resultas genetics,result of a of complex aenvironment, complex metabolic metabolic agricultural network network that practices, canthat be can influencedand be postharvestinfluenced by several by handling several factors, such factors,and storage. assuch genetics, However,as genetics, environment, recent environment, findings agricultural show agricultural that practices, the practices, biosynthesis and postharvest and ofpostharvest the compounds handling handling and can storage. andbe remarkably storage.However, However, influenced recent recent findings by other findings show factors, thatshow such the that biosynthesis as the enzyme biosynthesis specificity of thecompounds of the of genecompounds canadaptation be remarkablycan be[192,193] remarkablyinfluenced leading influenced to by the other research by factors, other of suchfactors, new as steps. enzyme such Untilas specificityenzyme recently, specificity of the gene research adaptation of gene focus adaptation [192 was,193 to] leading [192,193]understandto leading the how research agricultureto the of research new practices steps. of new Until affect steps. recently, plant Until composition the recently, research the and focus research interfere was focus to in understand the was con- to how understandsumer´sagriculture perception how agriculture practices of aromatic affectpractices features plant affect composition[126,1 plant94], but composition and the interferelatest researchand in interfere the studies consumer in arethe´ shift-scon- perception sumer´sing fromof perception yield aromatic to quality of features aromatic factors. [126 features Nowadays,,194], but [126,1 the the94], latest trends but research the in consumption latest studies research areare studies mostly shifting are defined from shift- yield to ingby consumer’sfrom yield to preferences quality factors. (sustainability, Nowadays, nu thetrition, trends aromatic in consumption features, are novelty) mostly anddefined not byexclusively consumer’s by preferencesthe producer’s (sustainability, priorities [194]. nutrition, Genomic aromatic and metabolomic features, novelty) analysis and with not exclusivelyclarification byof thethe fundamentalproducer’s priorities metabolism [194]. of volatileGenomic compounds and metabolomic with aromatic analysis features with clarificationand their biosynthetic of the fundamental mechanisms, metabolism regulations, of volatile and localization compounds is with a hot aromatic topic [194]. features So, andlinkages their of biosynthetic the biosynthesis mechanisms, of aromatic regulations, features andand with localizationlocalization enzymatic isisendogenous aa hothot topictopic processes[194].[194]. So,So, linkageswill provide of the new biosynthesis insights into of the aromatic flavor cofeaturesntrol mechanism. with enzymatic Moreover, endogenous the association processes of willgenome provide and newmetabolome insights intoanalysis the flavor with identification control mechanism. of key enzymaticMoreover, changesthe association occurred of genomein physiological and metabolome processes analysis would addresswith identification new opportunities of key enzymatic to increase changes the contents occurred of inspecific physiological compounds, processes particularly would thoseaddress with new importance opportunities for consumerto increase acceptance. the contents This of specific compounds, particularly those with importanceimportance forfor consumerconsumer acceptance.acceptance. ThisThis

Foods 2021, 10, 106 22 of 29

quality factors. Nowadays, the trends in consumption are mostly defined by consumer’s preferences (sustainability, nutrition, aromatic features, novelty) and not exclusively by the producer’s priorities [194]. Genomic and metabolomic analysis with clarification of the fundamental metabolism of volatile compounds with aromatic features and their biosynthetic mechanisms, regulations, and localisation is a hot topic [194]. So, linkages of the biosynthesis of aromatic features with enzymatic endogenous processes will provide new insights into the flavour control mechanism. Moreover, the association of genome and metabolome analysis with identification of key enzymatic changes occurred in physiological processes would address new opportunities to increase the contents of specific compounds, particularly those with importance for consumer acceptance. This approach will open the possibility to produce vegetables and MAP species with an enhanced content of a specific volatile or nonvolatile compound, with greater biological properties. Additionally, it will speed up the discovery of new or unknown chemosensory-active molecules and understanding of their biochemical interactions with main food matrix constituents. Likewise, it will open ways of direct improvement of foods by adapting processing parameters that can help to overcome taste defects or undesirable aromatic features, without the addition of any artificial ingredients.

4. Final Remarks Vegetables and MAPs are two important sources of bioactive and volatile compounds that are responsible for consumer perceptions on their importance in human health. Hun- dreds of studies using in vitro and in vivo models have shown that phenolics and volatile compounds are directly involved in different degenerative cellular mechanisms and thus are being considered as key compounds to reduce or to inhibit pro-oxidant and inflammatory processes. The combination of such compounds gives us an important view on the quality of vegetables and MAPs. Thus, it is important to understand what types of compounds are present in vegetables and MAPs, the relations between them, and how they can be affected by biotic or abiotic factors. This review summarises all these aspects. This information is important to a better understanding of all the processes behind the formation of volatile and nonvolatile compounds as well as their bioactivities, their interaction with other compounds, but, more importantly, how they influence the consumer’s perception of quality. Moreover, their influence on the human tendency to buy vegetables and MAPs is also supported by this type of information. This is true to all plant species reported in this work, but also to those not included here, and a continuous effort to identify volatile and nonvolatile compounds is ongoing. Furthermore, the improvement of aromatic features is fundamental and must be achieved without compromising other quality traits of crops.

Author Contributions: Conceptualization, T.P. and A.A.; writing—original draft preparation, T.P., A.A., F.C., E.B., M.C.M., I.O., J.F.-C., A.V., R.A. and B.G.; writing—review and editing, T.P. and A.A. and F.C. and B.G.; supervision, T.P. and A.A. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the CQ-VR under [grant number UIDB/00616/2020 and UIDP/00616/2020]; CITAB [grant number UIDB/04033/2020]; FCT—Portugal and COMPETE and by FEDER/COMPETE/POCI–Operational Competitiveness and Internationalization Program under Project POCI-01-0145-FEDER-006958. Institutional Review Board Statement: Not applicable. Informed Con sent Statement: Not applicable. Data Availability Statement: Not applicable. Conﬂicts of Interest: The authors declare no conﬂict of interest. Foods 2021, 10, 106 23 of 29

References 1. Kyriacou, M.C.; Rouphael, Y. Towards a new definition of quality for fresh fruits and vegetables. Sci. Hortic. 2018, 234, 463. [CrossRef] 2. Klee, H.J. Improving the flavour of fresh fruits: Genomics, biochemistry, and biotechnology. New Phytol. 2010, 187, 44. [CrossRef] [PubMed] 3. Dias, J.S.; Ryder, E.J. World vegetable industry: Production, breeding, trends. In Horticultural Reviews; Janick, J., Ed.; Wiley- Blackwell: Hoboken, NJ, USA, 2011; pp. 299–356. 4. Gonçalves, B.; Oliveira, I.; Bacelar, E.; Morais, M.C.; Aires, A.; Cosme, F.; Ventura-Cardoso, J.; Anjos, R.; Pinto, T. Aromas and flavours of fruits. In Generation of Aromas and Flavours; Vilela, A., Ed.; IntechOpen: London, UK, 2018; pp. 9–31. 5. Mouritsen, O.; Styrbaek, G.; Mouthfeel, K. Crucial to Whether We Like the Food or not. Available online: http://www.taste-for- life.org/artikler/mouthfeel-crucial-whether-we-food-or-not (accessed on 26 June 2019). 6. Gurib-Fakim, A. Medicinal plants: Traditions of yesterday and drugs of tomorrow. Mol. Aspects Med. 2006, 27, 1–93. [CrossRef] [PubMed] 7. Kaur, S.; Das, M. Functional foods: An overview. Food Sci. Biotechnol. 2011, 20, 861. [CrossRef] 8. Sánchez-Moreno, C. Compuestos polifenólicos: Estructura y classificación: Presencia en alimentos y consumo: Biodisponibilidad y metabolismo. Alimentaria 2002, 329, 19–28. 9. Bravo, L. Polyphenols: Chemistry, dietary sources, metabolism, and nutritional significance. Nutr. Rev. 1998, 56, 317. [CrossRef] 10. Teixeira, J.; Gaspar, A.; Garrido, E.M.; Garrido, J.; Borges, F. Hydroxycinnamic acid antioxidants: An electrochemical overview. Biomed. Res. Int. 2013.[CrossRef] 11. Vilela, A.; Pinto, T. Grape Infusions: The Flavour of Grapes and Health-Promoting Compounds in Your Tea Cup. Beverages 2019, 5, 48. [CrossRef] 12. Lutz, M.; Fuentes, E.; Ávila, F.; Alarcón, M.; Palomo, I. Roles of Phenolic Compounds in the Reduction of Risk Factors of Cardiovascular Diseases. Molecules 2019, 24, 366. [CrossRef] 13. Llano, D.G.; Liu, H.; Khoo, K.; Moreno-Arribas, M.V.; Bartolomé, B. Some New Findings Regarding the Antiadhesive Activity of Cranberry Phenolic Compounds and Their Microbial-Derived Metabolites against Uropathogenic Bacteria. J. Agric. Food Chem. 2019, 67, 2166–2174. [CrossRef] 14. Robbins, R. Phenolic acids in foods: An overview of analytical methodology. J. Agric. Food Chem. 2003, 51, 2866–2887. [CrossRef] [PubMed] 15. Giada, M.L.R. Food phenolic compounds: Main classes, sources and their antioxidant power. In Oxidative Stress and Chronic Degenerative Diseases—A Role for Antioxidants; González, J.A.M., Ed.; InTech: Rijeka, Croatia, 2013; pp. 87–112. 16. Khadem, S.; Marles, R.J. Monocyclic phenolic acids; hydroxy- and polyhydroxybenzoic acids: Occurrence and recent bioactivity studies. Molecules 2010, 15, 7985. [CrossRef][PubMed] 17. Sroka, Z.; Cisowski, W. Hydrogen peroxide scavenging, antioxidant and anti-radical activity of some phenolic acids. Food Chem. Toxicol. 2003, 41, 753–758. [CrossRef] 18. Sircar, D.; Mitra, A. Accumulation of p-hydroxybenzoic acid in hairy roots of Daucus carota 2: Confirming biosynthetic steps through feeding of inhibitors and precursors. J. Plant. Physiol. 2009, 166, 1370–1380. [CrossRef][PubMed] 19. Hur, J.M.; Park, J.G.; Yang, K.H.; Park, J.C.; Park, J.R.; Chun, S.S.; Choi, J.S.; Choi, J.W. Effect of methanol extract of Zanthoxylum piperitum leaves and of its compound, protocatechuic acid, on hepatic drug metabolising enzymes and lipid peroxidation in rats. Biosci. Biotechnol. Biochem. 2003, 67, 945. [CrossRef][PubMed] 20. Kono, Y.; Shibata, H.; Kodama, Y.; Sawa, Y. The suppression of the N-nitrosating reaction by chlorogenic acid. Biochem. J. 1995, 312, 947–953. [CrossRef] 21. Al-Sereitia, M.R.; Abu-Amerb, K.M.; Sena, P. Pharmacology of rosemary (Rosmarinus officinalis Linn.) and its therapeutic potentials. Indian J. Exp. Biol. 1999, 37, 124. [PubMed] 22. Zheng, W.; Wang, S. Antioxidant activity and phenolic compounds in selected herbs. J. Agric. Food Chem. 2001, 49, 5165–5170. [CrossRef] 23. Sytar, O.; Hemmerich, I.; Zivcak, M.; Rauh, C.; Brestic, M. Comparative analysis of bioactive phenolic compounds composition from 26 medicinal plants. Saudi J. Biol. Sci. 2018, 25, 631–641. [CrossRef] 24. Keating, G.J.; O’Kennedy, R. The chemistry and occurrence of coumarins. In Coumarins: Biology, Applications and Mode of Action; O’Kennedy, R., Thornes, R.D., Eds.; John Wiley & Sons Ltd.: Chichester, UK, 1997; pp. 23–66. 25. Matos, M.J.; Santana, L.; Uriarte, E.; Abreu, O.; Molina, E.; Yordi, E. Coumarins—An Important Class of Phytochemicals. In Phytochemicals—Isolation, Characterisation and Role in Human Health; Rao, V., Rao, L., Eds.; InTech: Rijeka, Croatia, 2015; pp. 113–140. 26. Gopi, C.; Dhanaraju, M.D. Synthesis, characterisation and anti-microbial action of novel azo dye derived from 4-methyl 7-OH 8 nitro coumarin. J. Pharm. Res. 2011, 4, 1037–1038. 27. Raev, L.; Voinov, E.; Ivanov, I.; Popov, D. Antitumor activity of some coumarin derivatives. Pharmazie 1997, 45, 696–697. 28. Nofal, Z.L.; El-Zahar, M.; Abd El-Karim, S. Novel coumarin derivatives with expected biological activity. Molecules 2000, 5, 99–113. [CrossRef] 29. Landete, J.M. Plant, mammalian lignans: A review of source, intake metabolism, intestinal bacteria, health. Food Res. Int. 2012, 46, 410. [CrossRef] Foods 2021, 10, 106 24 of 29

30. Rothwell, J.; Pérez-Jiménez, J.; Neveu, V.; Medina-Ramon, A.; M’Hiri, N.; Garcia Lobato, P.; Manach, C.; Knox, K.; Eisner, R.; Wishart, D.; et al. Phenol-Explorer 3.0: A major update of the Phenol-Explorer database to incorporate data on the effects of food processing on polyphenol content. Database (Oxf.) 2013, bat070. [CrossRef][PubMed] 31. Peterson, J.; Dwyer, J.; Adlercreutz, H.; Scalbert, A.; Jacques, P.; McCullough, M.L. Dietary lignans: Physiology and potential for cardiovascular disease risk reduction. Nutr. Rev. 2010, 68, 571. [CrossRef] 32. Kumar, S.; Pandey, A.K. Chemistry, and biological activities of flavonoids: An overview. Sci. World J. 2013.[CrossRef] 33. Shahidi, F.; Naczk, M. Phenolics in Food and Nutraceuticals; CRC Press: Boca Raton, FL, USA, 2003. 34. Chu, Y.H.; Chang, C.L.; Hsu, H.F. Flavonoid content of several vegetables and their antioxidant activity. J. Sci. Food Agric. 2000, 80, 561. [CrossRef] 35. Hertog, M.G.L.; Hollman, P.C.H.; Katan, M.B. Content of potentially anticarcinogenic flavonoids of 28 vegetables and 9 fruits commonly consumed in the Netherlands. J. Agric. Food Chem. 1992, 40, 2379. [CrossRef] 36. Sakakibara, H.; Honda, Y.; Nakagawa, S.; Ashida, H.; Kanazawa, K. Simultaneous determination of all polyphenols in vegetables, fruits, and teas. J. Agric. Food Chem. 2003, 51, 571–581. [CrossRef] 37. Manach, C.; Scalbert, A.; Morand, C.; Rémésy, C.; Jiménez, L. Polyphenols: Food sources and bioavailability. Am. J. Clin. Nutr. 2004, 79, 727–747. [CrossRef] 38. Romani, A.; Vignolini, P.; Galardi, C.; Mulinacci, N.; Benedettelli, S.; Heimler, D. Germplasm characterisation of Zolfino Landraces (Phaseolus vulgaris L.) by flavonoid content. J. Agric. Food Chem. 2004, 52, 3838–3842. [CrossRef][PubMed] 39. Price, K.R.; Colquhoun, I.J.; Barnes, K.A.; Rhodes, M.J.C. Composition, and content of flavonol glycosides in green beans and their fate during processing. J. Agric. Food Chem. 1998, 46, 4898–4903. [CrossRef] 40. Ewald, C.; Fjelkner-Modig, S.; Johansson, K.; Sjöholm, I.; Ákesson, B. Effect of processing on major flavonoids in processed onoins, green beans, and peas. Food Chem. 1999, 64, 231–235. [CrossRef] 41. Andlauer, W.; Stumpf, C.; Hubert, M.; Rings, A.; Furst, P. Influence of cooking process on phenolic marker compounds of vegetables. Int. J. Vitam. Nutr. Res. 2003, 73, 152–159. [CrossRef] 42. Franke, A.A.; Custer, L.J.; Arakaki, C.; Murphy, S.P. Vitamin C and flavonoid levels of fruits and vegetables consumed in Hawaii. J. Food Comp. Anal. 2004, 17, 1–35. [CrossRef] 43. Hempel, J.; Böhm, H. Quality and quantity of prevailing flavonoid glycosides of yellow and green French beans (Phaseolus vulgaris L.). J. Agric. Food Chem. 1996, 44, 2114–2116. [CrossRef] 44. Justesen, U.; Knuthsen, P.; Leth, T. Quantitative analysis of flavonols, flavones, and flavonones in fruits, vegetables, and beverages by high-performance liquid chromatography with photo-diode array and mass spectrometric detection. J. Chromatogr. A 1998, 799, 101–110. [CrossRef] 45. Erlund, I. Review of the flavonoids quercetin, hesperetin, and naringenin. Dietary sources, bioactivities, bioavailability, and epidemiology. Nutr. Res. 2004, 24, 851. [CrossRef] 46. Krause, M.; Galensa, R. Determination of naringenin and naringenin-chalcone in tomato skins by reversedphase HPLC after solid phase extraction. Z. Lebensm. Unters. Forsch. 1992, 194, 29. [CrossRef] 47. D’Archivio, M.; Filesi, C.; Benedetto, R.D.; Gargiulo, R.; Giovannini, C.; Masella, R. Polyphenols, dietary sources and bioavailability. Ann. Ist. Super. Sanita 2000, 43, 348. [PubMed] 48. Helsper, J.P.F.G.; Kolodziej, H.; Hoogendijk, J.M.; Vannorel, A. Characterisation and trypsin inhibitor activity of proanthocyanidins from vicia-faba. Phytochemistry 1993, 34, 1255. [CrossRef] 49. Moneam, N. Effects of presoaking on faba bean enzyme inhibitors and polyphenols after cooking. J. Agric. Food Chem. 1990, 38, 1479–1482. [CrossRef] 50. Deshpande, S.S.; Cheryan, M. Determination of phenolic compounds of dry beans using vanillin, redox and precipitation assays. J. Food Sci. 1987, 52, 332. [CrossRef] 51. Arts, I.C.W.; van de Putte, B.; Hollman, P.C.H. Catechin content of foods commonly consumed in the Netherlands. Fruits, vegetables, staple foods, and processed foods. J. Agric. Food Chem. 2000, 48, 1746. [CrossRef][PubMed] 52. De Pascual-Teresa, S.; Santos-Buelga, C.; Rivas-Gonzalo, J.C. Quantitative analysis of flavan-3-ols in Spanish foodstuffs and beverages. J. Agric. Food Chem. 2000, 48, 5331. [CrossRef] 53. Vinson, J.; Su, X.; Zubik, L.; Bose, P. Phenol antioxidant quantity and quality in foods: Fruits. J. Agric. Food Chem. 2001, 49, 5315–5321. [CrossRef] 54. Kaur, H.; Kaur, G. A critical appraisal of solubility enhancement techniques of polyphenols. J. Pharm. 2014.[CrossRef] 55. Tsao, R. Chemistry and biochemistry of dietary polyphenols. Nutrients 2010, 2, 1231–1246. [CrossRef] 56. Wu, X.; Beecher, G.R.; Holden, J.M.; Haytowitz, D.B.; Gebhardt, S.E.; Prior, R.L. Concentrations of anthocyanins in common foods in the United States and estimation of normal consumption. J. Agric. Food Chem. 2006, 54, 4069–4075. [CrossRef] 57. Chang, Q.; Wong, Y.-S. Identification of flavonoids in Hakmeitau beans (Vigna sinensis) by high performance liquid chromatography-electron-spray mass spectrometry (LCESI/MS). J. Agric. Food Chem. 2004, 52, 6694–6699. [CrossRef] 58. He, J.; Giusti, M.M. Anthocyanins: Natural colourants with health-promoting properties. Ann. Rev. Food Sci. Technol. 2010, 1, 163. [CrossRef][PubMed] 59. Tuli, R.T.; Rahman, M.M.; Abdullah, A.T.; Akhtauzzaman, M.; Islam, S.N. Phytochemicals—Tannins in some Leafy Vegetables of Bangladesh. J. Nutr. 2016, 3, 150. Available online: https://www.opensciencepublications.com/fulltextarticles/IJN-2395-2326-3- 150.html (accessed on 14 November 2020). Foods 2021, 10, 106 25 of 29

60. Fernández-Mar, M.I.; Mateos, R.; Garcıa-Parrilla, M.C.; Puertas, B.; Cantos-Villar, E. Bioactive compounds in wine: Resveratrol, hydroxytyrosol and melatonin: A review. Food Chem. 2012, 130, 797. [CrossRef] 61. Gambini, J.; Inglés, M.; Olaso, G.; Lopez-Grueso, R.; Bonet-Costa, V.; Gimeno-Mallench, L.; Mas-Bargues, C.; Abdelaziz, K.M.; Gomez-Cabrera, M.C.; Vina, J.; et al. Properties of Resveratrol: In Vitro and In Vivo studies about metabolism, bioavailability, and biological effects in animal models and humans. Oxid. Med. Cell Longev. 2015, 837042. [CrossRef] 62. Chung, M.I.; Teng, C.M.; Cheng, K.L.; Ko, F.N.; Lin, C.N. An antiplatelet principle of Veratrum formosanum. Planta Med. 1992, 58, 274. [CrossRef] 63. Cichewicz, R.H.; Kouzi, S.A. Biotransformation of resveratrol to piceid by Bacillus Cereus. J. Nat. Prod. 1998, 61, 1313–1314. [CrossRef][PubMed] 64. Peng, X.L.; Xu, j.; Sun, X.-F.; Ying, C.-J.; Hao, L.-P. Analysis of trans-resveratrol and trans-piceid in vegetable foods using high-performance liquid chromatography. Int. J. Food Sci. Nutr. 2015, 66, 729. [CrossRef] 65. Sebastià, N.; Montoro, A.; León, Z.; Soriano, J.M. Searching trans-resveratrol in fruits and vegetables: A preliminary screening. J. Food Sci. Technol. 2017, 54, 842–845. [CrossRef][PubMed] 66. Panche, N.; Diwan, A.; Chandra, S. Flavonoids: An overview. J. Nutr. Sci. 2016, 5, e47. [CrossRef] 67. Rossi, M.; Bosetti, C.; Negri, E.; Lagiou, P.; Vecchia, C. Flavonoids, proanthocyanidins, and cancer risk: A network of case-control studies from Italy. Nutr. Cancer 2010, 62, 871–877. [CrossRef] 68. Wedick, N.; Pan, A.; Cassidy, A.; Rimm, E.; Sampson, L.; Rosner, B.; Willet, W.; Hu, F.; Sun, Q.; Dam, R. Dietary flavonoid intakes and risk of type 2 diabetes in US men and women. Am. J. Clin. Nutr. 2012, 95, 925–933. [CrossRef][PubMed] 69. Bousova, I.; Skalova, L. Inhibition and induction of glutathione S-transferases by flavonoids: Possible pharmacological and toxicological consequences. Drug Metab. Rev. 2012, 44, 267. [CrossRef] 70. Wuttke, W.; Jarry, H.; Seidlova-Wuttke, D. Isoflavones—Safe food additives or dangerous drugs? Ageing Res. Rev. 2007, 6, 150–188. [CrossRef][PubMed] 71. Williamson, G.; Holst, B. Dietary reference intake (DRI) value for dietary polyphenols: Are we heading in the right direction? Brit. J. Nutr. 2008, 99, S55–S58. [CrossRef][PubMed] 72. Andres, S.; Abraham, K.; Appel, K.; Lampen, A. Risks and benefits of dietary isoflavones for cancer. Crit. Rev. Toxicol. 2011, 41, 463. [CrossRef] 73. Del Rio, D.; Bresciani, L. Phenolic compounds as functional ingredients and nutraceuticals: The case of Juice PLUS+. FASEB J. 2018, 31, 646. [CrossRef] 74. Kaurinovic, B.; Vastag, D. Flavonoids and phenolic acids as potential natural antioxidants. In Antioxidants; Shalaby, E., Ed.; IntechOpen: London, UK, 2019; Available online: https://www.intechopen.com/books/antioxidants/flavonoids-and-phenolic- acids-as-potential-natural-antioxidants (accessed on 17 November 2020). [CrossRef] 75. Huang, W.-Y.; Cai, Y.-Z.; Zhang, Y. Natural phenolic compounds from medicinal herbs and dietary plants: Potential use for cancer prevention. Nut. Cancer 2009, 62, 1. [CrossRef] 76. Piluzza, G.; Bullitta, S. Correlations between phenolic content and antioxidant properties in twenty-four plant species of traditional ethnoveterinary use in the Mediterranean area. Pharm. Biol. 2011, 49, 240. [CrossRef] 77. Tungmunnithum, D.; Thongboonyou, A.; Pholboon, A.; Yangsabai, A. Flavonoids and other phenolic compounds from medicinal plants for pharmaceutical and medical aspects: An overview. Medicines 2018, 5, 93. [CrossRef] 78. Salem, M.B.; Affes, H.; Athmouni, K.; Ksouda, K.; Dhouibi, R.; Sahnoun, Z.; Hammami, S.; Zeghal, K.M. Chemicals compositions, antioxidant and anti-inflammatory activity of Cynara scolymus leaves extracts, and analysis of major bioactive polyphenols by HPLC. Evid Based Complement. Altern. Med. 2017.[CrossRef] 79. Sharma, K.; Mahato, N.; Lee, Y.R. Systematic study on active compounds as antibacterial and antibiofilm agent in aging onions. J. Food Drug Anal. 2018, 26, 518. [CrossRef][PubMed] 80. Dzotam, J.K.; Simo, I.K.; Bitchagno, G.; Celik, I.; Sandjo, L.P.; Tane, P.; Kuete, V. In vitro antibacterial and antibiotic modifying activity of crude extract, fractions and 30, 40, 7-trihydroxyflavone from Myristica fragrans Houtt against MDR Gram-negative enteric bacteria. BMC Complement Altern. Med. 2018, 18.[CrossRef] 81. Pilar de Torre, M.; Vizmanos, J.L.; Cavero, R.Y.; Calvo, M.I. Improvement of antioxidant activity of oregano (Origanum vulgare L.) with an oral pharmaceutical form. Biomed. Pharm. 2020, 129.[CrossRef] 82. Li, Z.; Lee, H.W.; Liang, X.; Liang, D.; Wang, Q.; Huang, D.; Ong, C.N. Profiling of phenolic compounds and antioxidant activity of 12 cruciferous vegetables. Molecules 2018, 23, 1139. [CrossRef][PubMed] 83. Liu, D.-K.; Xu, C.-C.; Zhang, L.; Ma, H.; Chen, X.-J.; Sui, Y.-C.; Zhang, H.-Z. Evaluation of bioactive components and antioxidant capacity of four celery (Apium graveolens L.) leaves and petioles. Int. J. Food Prop. 2020, 23, 1097. [CrossRef] 84. Petropoulos, S.; Fernandes, A.; Barros, L.; Ciric, A.; Sokovic, M.; Ferreira, I.C.F.R. Antimicrobial and antioxidant properties of various Greek garlic genotypes. Food Chem. 2018, 245, 7. [CrossRef] 85. Phan, A.; Netzel, G.; Chhim, P.; Netzel, M.E.; Sultanbawa, Y. Phytochemical characteristics and antimicrobial activity of Australian grown garlic (Allium sativum L.) cultivars. Foods 2019, 8, 358. [CrossRef] 86. Deng, G.-F.; Lin, X.; Xu, X.-R.; Gao, L.-L.; Xie, J.-F.; Li, H.-B. Antioxidant capacities and total phenolic contents of 56 vegetables. J. Funct. Foods 2013, 5, 260. [CrossRef] 87. Radovanović,B.; Mladenović,J.; Radovanović,A.; Pavlović,R.; Nikolić,V. Phenolic composition, antioxidant, antimicrobial and cytotoxic activities of Allium porrum L. (Serbia) extracts. J. Food Nutr. Res. 2015, 3, 564. [CrossRef] Foods 2021, 10, 106 26 of 29

88. Zeb, A. Phenolic profile and antioxidant potential of wild watercress (Nasturtium officinale L.). SpringerPlus 2015, 4.[CrossRef] 89. Jarial, R.; Thakur, S.; Sakinah, M.; Zularisam, A.W.; Sharad, A.; Kanwar, S.S.; Singh, L. Potent anticancer, antioxidant and antibacterial activities of isolated flavonoids from Asplenium Nidus. J. King Saud Univ. -Sci. 2018, 30, 185. [CrossRef] 90. Ozkur, M.K.; Bozkurt, M.S.; Balabanli, B.; Aricioglu, A.; Ilter, N.; Gurer, M.A.; Inaloz, H.S. The effect of EGb 761 on lipid peroxide levels and superoxide dismutase activity in sunburn. Photodermatol. Photoimmunol. Photomed. 2002, 18, 117. [CrossRef][PubMed] 91. Meng, X.H.; Liu, C.; Fan, R.; Zhu, L.F.; Yang, S.X.; Zhu, H.T.; Wang, D.; Yang, C.R.; Zhang, Y.J. Antioxidative flavan-3-ol dimers from the leaves of Camellia fangchengensis. J. Agric. Food Chem. 2018, 6, 247. [CrossRef][PubMed] 92. Rupasinghe, V.H.P.; Boehm, M.M.A.; Sekhon-Loodu, S.; Parmar, I.; Bors, B.; Jamieson, A.R. Anti-inflammatory activity of haskap cultivars is polyphenols-dependent. Biomolecules 2015, 5, 1079. [CrossRef][PubMed] 93. Lopes, C.L.; Pereira, E.; Soković,M.; Carvalho, A.M.; Barata, A.M.; Lopes, V.; Rocha, F.; Calhelha, R.C.; Barros, L.; Ferreira, I.C.F.R. Phenolic composition and bioactivity of Lavandula pedunculata (Mill.) Cav. samples from different geographical origin. Molecules 2018, 23, 1037. [CrossRef] 94. Kontogianni, V.G.; Tomic, G.; Nikolic, I.; Nerantzaki, A.; Sayyad, A.; Stosic-Grujicic, N.; Stojanovic, S.; Gerothanassis, I.P.; Tzakos, A.G. Phytochemical profile of Rosmarinus officinalis and Salvia officinalis extracts and correlation to their antioxidant and anti-proliferative activity. Food Chem. 2013, 136, 120. [CrossRef] 95. Jaouadi, R.; Silva, A.; Boussaid, M.; Yahia, I.; Cardoso, S.M.; Zaouali, Y. Differentiation of phenolic composition among tunisian Thymus algeriensis Boiss. et Reut. (Lamiaceae) populations: Correlation to bioactive activities. Antioxidants 2019, 8, 515. [CrossRef] 96. Scalbert, A.; Williamson, G. Dietary intake, and bioavailability of polyphenols. J. Nutr. 2000, 130, 2073–2085. [CrossRef] 97. Duda-Chodak, A.; Tarko, T.; Satora, P.; Sroka, P. Interaction of dietary compounds, especially polyphenols, with the intestinal microbiota: A review. Eur. J. Nutr. 2015, 54, 325. [CrossRef] 98. Bian, Y.; Wei, J.; Zhao, C.; Li, G. Natural polyphenols targeting senescence: A novel prevention and therapy strategy for cancer. Int. J. Mol. Sci. 2020, 21, 684. [CrossRef] 99. Lee, H.C.; Jenner, A.M.; Low, C.S.; Lee, Y.K. Effect of tea phenolics and their aromatic fecal bacterial metabolites on intestinal microbiota. Res. Microbiol. 2006, 157, 876–884. [CrossRef][PubMed] 100. Cardona, F.; Andrés-Lacueva, C.; Tulipani, S.; Tinahones Francisco, J.; Queipo-Ortuño, M.I. Benefits of polyphenols on gut microbiota and implications in human health. J. Nutr. Biochem. 2013, 24, 1415–1422. [CrossRef][PubMed] 101. Kawabata, K.; Yoshioka, Y.; Terao, J. Role of Intestinal Microbiota in the Bioavailability and Physiological Functions of Dietary Polyphenols. Molecules 2019, 24, 370. [CrossRef][PubMed] 102. Parkar, S.G.; Stevenson, D.E.; Skinner, M.A. The potential influence of fruit polyphenols on colonic microflora and human gut health. Int. J. Food Microbiol. 2008, 124, 295. [CrossRef][PubMed] 103. Carmody, R.N.; Turnbaugh, P.J. Host-microbial interactions in the metabolism of therapeutic and diet-derived xenobiotics. J. Clin. Investig. 2014, 124, 4173. [CrossRef] 104. Rastmanesh, R. High polyphenol, low probiotic diet for weight loss because of intestinal microbiota interaction. Chem Biol Interact. 2011, 189, 1. [CrossRef] 105. Sanders, M.E.; Merenstein, D.J.; Reid, G.; Gibson, G.R.; Rastall, R.A. Probiotics and prebiotics in intestinal health and disease: From biology to the clinic. Nat. Rev. Gastroenterol Hepatol. 2019, 16, 605–616. [CrossRef] 106. Shortt, C.; Hasselwander, O.; Meynier, A.; Nauta, A.; Fernández, E.N.; Putz, P.; Antoine, J.M. Systematic review of the effects of the intestinal microbiota on selected nutrients and non-nutrients. Eur. J. Nut. 2018, 57, 25–49. [CrossRef] 107. Singh, A.K.; Cabral, C.; Kumar, R.; Ganguly, R.; Pandey, A.K. Beneficial effects of dietary polyphenols on gut microbiota and strategies to improve delivery efficiency. Nutrients 2019, 11, 2216. [CrossRef] 108. Alves-Santos, A.M.; Sugizaki, C.S.A.; Lima, G.C.; Naves, M.M.V. Prebiotic effect of dietary polyphenols: A systematic review. J. Funct. Foods 2020, 74, 104169. [CrossRef] 109. Gibson, G.R.; Roberfroid, M.B. Dietary modulation of the human colonic microbiota: Introducing the concept of prebiotics. J. Nutr. 1995, 125, 1401–1412. [CrossRef] 110. Gibson, G.R.; Scott, K.P.; Rastall, R.A.; Tuohy, K.M.; Hotchkiss, A.; Dubert-Ferrandon, A.; Gareau, M.; Murphy, E.F.; Saulnier, D.; Loh, G.; et al. Dietary prebiotics: Current status and new definition. Food Sci. Technol. Bull. Funct. Foods 2010, 7, 1. [CrossRef] 111. Parada, J.; Aguilera, J.M. Food microstructure affects the bioavailability of several nutrients. J. Food Sci. 2007, 72, 21. [CrossRef] 112. Kemperman, R.A.; Bolca, S.; Roger, L.C.; Vaughan, E.E. Novel approaches for analysing gut microbes and dietary polyphenols: Challenges and opportunities. Microbiology 2010, 156, 3224. [CrossRef] 113. Williamson, G.; Manach, C. Bioavailability and bioefficacy of polyphenols in humans. II. Review of 93 intervention studies. Am. J. Clin. Nutr. 2005, 81, 243. [CrossRef] 114. Serreli, G.; Deiana, M. In vivo formed metabolites of polyphenols and their biological efficacy. Food Funct. 2019, 10, 6999. [CrossRef] 115. Lin, D.; Xiao, M.; Zhao, J.; Li, Z.; Xing, B.; Li, X.; Kong, M.; Li, L.; Zhang, Q.; Liu, Y.; et al. An overview of plant phenolic compounds and their importance in human nutrition and management of type 2 diabetes. Molecules 2016, 21, 1374. [CrossRef] 116. Raj, P.; Louis, X.L.; Thandapilly, S.J.; Movahed, A.; Zieroth, S.; Netticadan, T. Potential of resveratrol in the treatment of heart failure. Life Sci. 2014, 95, 63–71. [CrossRef] 117. Cheynier, V. Phenolic compounds: From plants to foods. Phytochem. Rev. 2012, 11, 153–177. [CrossRef] 118. Jacobo-Velázquez, D.A.; Cisneros-Zevallos, L. Recent Advances in Plant Phenolics. Molecules 2017, 22, 1249. [CrossRef] Foods 2021, 10, 106 27 of 29

119. Liu, L.; Shen, B.J.; Xie, D.H.; Cai, B.C.; Qin, K.M.; Cai, H. Optimisation of ultra-sound-assisted extraction of phenolic compounds from Cimicifugae rhizoma with response surface methodology. Pharm. Mag. 2015, 11, 682–689. [CrossRef] 120. Fang, X.; Wang, J.; Hao, J. Simultaneous extraction, identification, and quantification of phenolic compounds in Eclipta prostrata using microwave-assisted extraction combined with HPLC-DAD-ESI-MS/MS. Food Chem. 2015, 188, 527–536. [CrossRef] 121. Lee, H.S.; Lee, H.J.; Yu, H.J.; Ju, D.W.; Kim, Y.; Kim, C.T.; Suh, H.J. A comparison between high hydrostatic pressure extraction and heat extraction of ginsenosides from ginseng (Panax ginseng CA Meyer). J. Sci. Food Agric. 2011, 91, 1466. [CrossRef] 122. Swallah, M.S.; Sun, H.; Affoh, R.; Fu, H.; Yu, H. Antioxidant Potential Overviews of Secondary Metabolites (Polyphenols) in Fruits. J. Food Sci. 2020, 2020.[CrossRef] 123. Capriotti, A.L.; Cavaliere, C.; Foglia, P.; Piovesana, S.; Ventura, S. Chromatographic methods coupled to mass spectrometry detection for the determination of phenolic acids in plants and fruits. J. Liq. Chromatogr. Relat. Technol. 2015, 38, 353–370. [CrossRef] 124. Da Silva, L.A.; Pezzini, B.R.; Soares, L. Spectrophotometric determination of the total flavonoid content in Ocimum basilicum L. (Lamiaceae) leaves. Pharm. Mag. 2015, 11, 96. [CrossRef] 125. Chambers, E.; Koppel, K. Associations of volatile compounds with sensory aroma and flavour: The complex nature of flavour. Molecules 2013, 18, 4887. [CrossRef] 126. Parker, J.K.; Elmore, S.; Methven, L. Flavour Development, Analysis, and Perception in Food and Beverages; Woodhead Publishing: Cambridge, UK, 2014. 127. Barret, D.; Beaulieu, J.; Shewfelt, R. Colour, flavour, texture, and nutritional quality of fresh-cut fruits and vegetables: Desirable levels, instrumental and sensory measurement, and the effects of processing. Crit. Rev. Food Sci. Nutr. 2010, 50, 369. [CrossRef] 128. Arah, I.; Amaglo, H.; Kumah, E.; Ofori, H. Preharvest and postharvest factors affecting the quality and shelf life of harvested tomatoes: A mini review. Int. J. Agron. 2015, 2015, 478041. [CrossRef] 129. Acree, T.; Arn, H. Flavornet and Human Odour Space. Available online: http://www.flavornet.org/index.html/ (accessed on 21 June 2019). 130. Pripis-Nicolau, L.; Revel, G.; Bertrand, A.; Maujean, A. Formation of flavour components by the reaction of amino acid and carbonyl compounds in mild conditions. J. Agric. Food Chem. 2000, 48, 3761. [CrossRef] 131. Tieman, D.; Bliss, P.; McIntyre, L.M.; Blandon-Ubeda, A.; Bies, D.; Odabasi, A.Z.; Rodríguez, G.R.; Van Der Knaap, E.; Taylor, M.G.; Goulet, C.; et al. The chemical interactions underlying tomato flavour preferences. Curr. Biol. 2012, 22, 1035. [CrossRef] 132. Rambla, J.L.; Medina, A.; Fernández-Del-Carmen, A.; Barrantes, W.; Grandillo, S.; Cammareri, M.; López-Casado, G.; Rodrigo, G.; Alonso, A.; García-Martínez, S.; et al. Identification, introgression, and validation of fruit volatile QTLs from a red-fruited wild tomato species. J. Exp. Bot. 2017, 68, 429. [CrossRef][PubMed] 133. Korkmaz, A.; Hayaloglu, A.; Atasoy, A. Evaluation of the volatile compounds of fresh ripened Capsicum annuum and its spice pepper (dried red pepper flakes and isot). LWT Food Sci. Technol. 2017, 84, 842. [CrossRef] 134. Maarse, H. Volatile Compounds in Foods and Beverages; CRC Press, Marcel Dekker Inc.: New York, NY, USA, 1991. 135. Forney, C.; Jordan, M. Induction of volatile compounds in broccoli by postharvest hot-water dips. J. Agric. Food Chem. 1998, 46, 5295–5301. [CrossRef] 136. Hansen, M.; Buttery, R.; Stern, D.; Cantwell, M.; Ling, L. Broccoli storage under low-oxygen atmosphere: Identification of higher boiling volatiles. J. Agric. Food Chem. 1992, 40, 850–852. [CrossRef] 137. Akpolat, H.; Barringer, S. The effect of pH and temperature on cabbage volatiles during storage. J. Food Sci. 2015, 80, S1878–S1884. [CrossRef] 138. Engel, E.; Baty, C.; Le Corre, D.; Souchon, I.; Martin, N. Flavour-active compounds potentially implicated in cooked cauliflower acceptance. J. Agric. Food Chem. 2002, 50, 6459. [CrossRef] 139. Jacobsson, A.; Nielsen, T.; Sjoholm, I. Influence of temperature, modified atmosphere packaging, and heat treatment on aroma compounds in broccoli. J. Agric. Food Chem. 2004, 52, 1607. [CrossRef] 140. Tang, J.; Zhang, Y.; Hartman, T.G.; Rosen, R.T.; Ho, C.T. Free glycosidically bound volatile compounds in fresh celery (Apium graveolens L.). J. Agric. Food Chem. 1990, 38, 1937. [CrossRef] 141. Sowbhagya, H. Chemistry, technology, and nutraceutical functions of celery (Apium graveolens L.): An overview. Crit. Rev. Food Sci. Nutr. 2014, 54, 389. [CrossRef] 142. Buescher, R.; Buescher, R. Production and stability of (E, Z)-2, 6-nonadienal, the major flavour volatile of cucumbers. J. Food Sci. 2001, 66, 357. [CrossRef] 143. Shan, C.; Wang, C.; Jin, J.; Wu, P. The analysis of volatile flavour components of Jin Xiang garlic and Tai’an garlic. Agric. Sci. 2013, 4, 41176. [CrossRef] 144. Mondy, N.; Duplat, D.; Christides, J.; Arnault, I.; Auger, J. Aroma analysis of fresh and preserved onions and leek by dual solid-phase microextraction-liquid extraction and gas chromatography-mass spectrometry. J. Chromatogr. A 2002, 963, 89. [CrossRef] 145. Nielsen, G.S.; Poll, L. Determination of odour active aroma compounds in freshly cut leek (Allium ampeloprasum var. Bulga) and in long-term stored frozen unblanched and blanched leek slices by gas chromatography olfactometry analysis. J. Agric. Food Chem. 2004, 52, 1642. [CrossRef] 146. Murray, K.; Shipton, J.; Whitfeld, F.; Last, J. The volatiles of off-flavoured unblanched green peas (Pisum sativum). J. Sci. Food Agric. 1976, 27, 1093. [CrossRef] Foods 2021, 10, 106 28 of 29

147. Hayata, Y.; Maneerat, C.; Kozuka, H.; Sakamoto, K.; Ozajima, Y. Flavour volatile analysis of ‘House Momotaro’ tomato fruit extract at different ripening stages by porapak Q column. J. Jpn. Soc. Hortic. Sci. 2002, 71, 473. [CrossRef] 148. Maneerat, C.; Hayata, Y.; Kozuka, H.; Sakamoto, K.; Osajima, Y. Application of the porapak Q column extraction method for tomato flavour volatile analysis. J. Agric. Food Chem. 2002, 50, 3401. [CrossRef] 149. Rosenkranz, M.; Schnitzler, J.-P. Plant Volatiles. In eLS; John Wiley & Sons, Ltd: Chichester, UK, 2016; pp. 1–9. [CrossRef] 150. Beaulieu, J.C. Effect of cutting and storage on acetate and nonacetate esters in convenient, ready-to-eat fresh-cut melons and apples. Hortscience 2006, 41, 65–73. [CrossRef] 151. Beaulieu, J.C. Within-season volatile and quality differences in stored fresh-cut cantaloupe cultivars. J. Agric. Food Chem. 2005, 53, 8679. [CrossRef] 152. Vincenti, S.; Mariani, M.; Alberti, J.C.; Jacopini, S.; Brunini-Bronzini de Caraffa, V.; Berti, L.; Maury, J. Biocatalytic Synthesis of Natural Green Leaf Volatiles Using the Lipoxygenase Metabolic Pathway. Catalysts 2019, 9, 873. [CrossRef] 153. MacLeod, A.J.; MacLeod, G.; Subramanian, G. Volatile aroma constituents of celery. Phytochemistry 1988, 27, 373. [CrossRef] 154. Legrum, C.; Slabizki, P.; Schmarr, H.G. Enantiodifferentiation of 3-Sec-butyl-2-methoxypyrazine in different species using multidimensional and comprehensive two-dimensional gas chromatographic approaches. Anal. Bioanal. Chem. 2015, 407, 253. [CrossRef] 155. Berger, R.G. Flavours and Fragrances—Chemistry, Bioprocessing, and Sustainability; Springer: Berlin, Germany, 2007. 156. Hacham, Y.; Avraham, T.; Amir, R. The N-terminal region of Arabidopsis cystathionine gamma-synthase plays an important regulatory role in methionine metabolism. Plant. Physiol. 2002, 128, 454. [CrossRef][PubMed] 157. Baldwin, E.; Scott, J.; Einstein, M.; Malundo, T.; Carr, B.; Shewfelt, R.; Tandon, K. Relationship between sensory and instrumental analysis for tomato flavour. J. Am. Soc. Hortic. Sci. 1998, 123, 906–915. [CrossRef] 158. Pott, D.M.; Osorio, S.; Vallarino, J.G. From central to specialized metabolism: An overview of some secondary compounds derived from the primary metabolism for their role in conferring nutritional and organoleptic characteristics to fruit. Front. Plant. Sci. 2019, 10.[CrossRef] 159. Kader, A.A. Flavour quality of fruits and vegetables. J. Sci. Food Agric. 2008, 88, 1863. [CrossRef] 160. Shim, S. Comparison of volatile and non-volatile compounds as antioxidant indicators of water spinach (Ipomoea aquatic Forsk.). J. Korean Soc. Appl. Biol. Chem. 2012, 55, 297. [CrossRef] 161. Ncube, B.; Staden, J.V. Tilting plant metabolism for improved metabolite biosynthesis and enhanced human benefit. Molecules 2015, 20, 12698–12731. [CrossRef] 162. D’Angelo, M.; Zanor, M.I.; Sance, M.; Cortina, P.R.; Boggio, S.B.; Asprelli, P.; Carrari, F.; Santiago, A.N.; Asís, R.; Peralta, I.E.; et al. Contrasting metabolic profiles of tasty Andean varieties of tomato fruit in comparison with commercial ones. J. Sci. Food Agric. 2018, 98, 4128–4134. [CrossRef] 163. Khokar, S.; Fenwick, G. Onions and related crops. In Encyclopedia of Food Sciences and Nutrition, 3rd ed.; Caballero, B., Ed.; Academic Press: London, UK, 2003; pp. 4267–4272. 164. Dufour, V.; Stahl, M.; Baysse, C. The antibacterial properties of isothiocyanates. Microbiology 2015, 161, 229. [CrossRef] 165. Wallock-Richards, D.; Doherty, C.; Doherty, L.; Clarke, D.; Place, M.; Govan, J.; Campopiano, D. Garlic revisited: Antimicrobial activity of allicin-containing garlic extracts against Burkholderia cepacia complex. PLoS ONE 2014, 9.[CrossRef] 166. Nicastro, H.; Ross, S.; Milner, J. Garlic and onions: Their cancer prevention properties. Cancer Prev. Res. 2015, 8, 181. [CrossRef] 167. Martí, R.; Roselló, S.; Cebolla-Cornejo, J. Tomato as a source of carotenoids and polyphenols targeted to cancer prevention. Cancers 2016, 8, 58. [CrossRef] 168. Schwab, W.; Davidovich-Rikanati, R.; Lewinsohn, E. Biosynthesis of plant-derived flavour compounds. Plant J. 2008, 54, 712. [CrossRef] 169. Oliveira, I.; Pinto, T.; Faria, M.; Bacelar, E.; Ferreira, H.; Correia, C.; Gonçalves, B. Morphometrics and chemometrics as tools for medicinal and aromatic plants characterisation. J. Appl. Bot. Food Qual. 2017, 90, 31. [CrossRef] 170. Kaefer, C.; Milner, J. The role of herbs and spices in cancer prevention. J. Nutr. Biochem. 2008, 19, 347. [CrossRef] 171. Aarland, R.; Bañuelos-Hernández, A.; Fragoso-Serrano, M.; Sierra-Palacios, E.; Díaz de León-Sánchez, F.; Pérez-Flores, L.; Rivera- Cabrera, F.; Mendoza-Espinoza, J. Studies on phytochemical, antioxidant, anti-inflammatory, hypoglycaemic and antiproliferative activities of Echinacea purpurea and Echinacea angustifolia extracts. Pharm. Biol. 2017, 55, 649–656. [CrossRef] 172. Barata, A.M.; Rocha, F.; Lopes, V.; Bettencourt, E.; Figueiredo, A.C. Medicinal and aromatic plants—Portugal. In Medicinal and Aromatic Plants of the World. Encyclopedia of Life Support. Systems (EOLSS), Developed under the Auspices of the UNESCO; Ozturk, M., Ameenah, G.-F.B., Eds.; Eolss Publishers: Oxford, UK, 2011. 173. Inoue, M.; Hayashi, S.; Craker, L. Culture, history, and applications of medicinal and aromatic plants in Japan. In Aromatic and Medicinal Plants-Back to Nature; El-Shemy, H.A., Ed.; IntechOpen: London, UK, 2017; pp. 95–110. 174. Maiti, S.; Geetha, K. Horticulture, floriculture (Ornamental, medicinal & aromatic crops). In Medicinal and Aromatic Plants in India; Maiti, S., Geetha, K., Eds.; National Research Center for Medicinal and Aromatic Plants: Gujarat, India, 2007; pp. 1–27. 175. Verpoorte, R. Pharmacognosy in new millennium: Lead finding and biotechnology. J. Pharm. Pharm. 2000, 52, 253. [CrossRef] [PubMed] 176. Jarić,S.; Kostic, O.; Mataruga, Z.; Pavlovic, D.; Pavlović,M.; Mitrović,M.; Pavlović,P. Traditional wound-healing plants used in the Balkan region (Southeast Europe). J. Ethnopharmacol. 2017, 211, 311. [CrossRef][PubMed] Foods 2021, 10, 106 29 of 29

177. Joy, P.P.; Thomas, J.; Joy, P.P.; Mathew, S.; Skaria, B. Plant sources of aroma chemicals and medicines in India. Chem. Ind. Dig. (Spec. Millenn. Issue) 2000, 104–108. Available online: https://www.researchgate.net/publication/305639154 (accessed on 10 October 2020). 178. Wachtel-Galor, S.; Benzie, I. Herbal medicine: An introduction to its history, usage, regulation, current trends, and research needs. In Herbal Medicine: Biomolecular and Clinical Aspects; Benzie, I.F.F., Wachtel-Galor, S., Eds.; CRC Press/Taylor & Francis: Boca Raton, FL, USA, 2011; pp. 1–10. 179. Bustos-Segura, C.; Padovan, A.; Kainer, D.; Foley, W.J.; Külheim, C. Transcriptome analysis of terpene chemotypes of Melaleuca alternifolia across different tissues. Plant. Cell Environ. 2017, 40, 2406. [CrossRef] 180. Satyal, P.; Murray, B.L.; McFeeters, R.L.; Setzer, W.N. Essential oil characterisation of Thymus vulgaris from various geographical locations. Foods 2016, 5, 70. [CrossRef] 181. Lee, S.; Umano, K.; Shibamoto, T.; Lee, S. Identification of volatile components in basil and thyme leaves and their antioxidant properties. Food Chem. 2005, 91, 131. [CrossRef] 182. Shahwar, M.K.; El-Ghorab, A.H.; Anjum, F.-M.; Butt, M.S.; Hussain, S.; Nadeem, M. Characterisation of coriander (Coriandrum sativum L.) seeds and leaves: Volatile and non-volatile extracts. Int. J. Food Prop. 2012, 15, 736. [CrossRef] 183. Díaz-Maroto, M.C.; Hidalgo, I.J.D.-M.; Sánchez-Palomo, E.; Pérez-Coello, M.S. Volatile components and key odourants of fennel (Foeniculum vulgare Mill.) and thyme (Thymus vulgaris L.) oil extracts obtained by simultaneous distillation-extraction and supercritical fluid extraction. J. Agric. Food Chem. 2005, 53, 5385. [CrossRef] 184. Ekundayo, O.; Laakso, I.; Hiltunen, R. Composition of ginger (Zingiber officinale Roscoe) volatile oils from Nigeria. Flav. Frag. J. 1988, 3, 85–90. [CrossRef] 185. Kizhakkayil, J.; Sasikumar, B. Characterisation of ginger (Zingiber officinale Rosc.) germplasm based on volatile and non-volatile components. Afr. J. Biotechnol. 2012, 11, 777. [CrossRef] 186. Torabbeigi, M.; Azar, P.A. Analysis of essential oil compositions of Lavandula angustifolia by HS-SPME and MAHS-SPME followed by GC and GC–MS. Acta Chromatogr. 2013, 25, 571. [CrossRef] 187. Mokhtarzadeh, S.; Demirci, B.; Goger, G.; Khawar, K.M.; Kirimer, N. Characterisation of volatile components in Melissa officinalis L. under in vitro conditions. J. Essent. Oil Res. 2017, 29, 299. [CrossRef] 188. Hatipi, M.; Papajani, V.; Cavar, S.; Koliqi, R. Analysis of volatile compounds of Origanum vulgare L. growing wild in Kosovo. J. Essent. Oil-Bear. Plants 2014, 17, 148–157. [CrossRef] 189. El-Zaeddi, H.; Martínez-Tomé, J.; Calín-Sánchez, Á.; Burló, F.; Carbonell-Barrachina, A.A. Volatile composition of essential oils from different aromatic herbs grown in Mediterranean regions of Spain. Foods 2016, 5, 41. [CrossRef] 190. Boix, Y.; Fung, V.; Pimentel, C.; Lage, C.L.S.; Kuster, R.M. Volatile compounds from Rosmarinus officinalis L. and Baccharis dracunculifolia DC. growing in southeast coast of Brazil. Química Nova 2010, 33, 255–257. [CrossRef] 191. Cozzolino, R.; Ramezani, S.; Martignetti, A.; Mari, A.; Piacente, S.; De Giulio, B. Determination of volatile organic compounds in the dried leaves of Salvia species by solid-phase microextraction coupled to gas chromatography mass spectrometry. Nat. Prod. Res. 2016, 30, 841–848. [CrossRef][PubMed] 192. Zhang, B.; Tieman, D.M.; Jiao, C.; Xu, Y.; Chen, K.; Fei, Z.; Giovannoni, J.J.; Klee, H.J. Chilling-induced tomato flavour loss is associated with altered volatile synthesis and transient changes in DNA methylation. Proc. Natl. Acad. Sci. USA 2016, 113, 12580. [CrossRef][PubMed] 193. Tieman, D.; Zhu, G.; Resende, M.F., Jr.; Lin, T.; Nguyen, C.; Bies, D.; Rambla, J.L.; Beltran, K.S.; Taylor, M.; Zhang, B.; et al. A chemical genetic roadmap to improved tomato flavour. Science 2017, 355, 391. [CrossRef][PubMed] 194. Klee, H.J.; Tieman, D.M. The genetics of fruit flavour preferences. Nat. Rev. Genet. 2018, 19, 347. [CrossRef][PubMed]