beverages Review Occurrence of Ochratoxin A in Coffee: Threads and Solutions—A Mini-Review Ana Lúcia Leitão 1,2 1 Departamento de Ciências e Tecnologia da Biomassa, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal; [email protected] 2 MEtRICs, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal Received: 29 December 2018; Accepted: 26 April 2019; Published: 8 May 2019 Abstract: Ochratoxin A (OTA) is a widespread bioactive extrolite from secondary metabolism of fungi which presence in foods like coffee is of public health concern, particularly for heavy drinkers. Coffee is one of the most consumed and appreciated non-alcoholic beverage in the world. Its production from the plantation to the coffee cup involves several steps that would determine the final concentration of OTA in the beverage. This review gives an overview of OTA contamination in roasted coffee beans in different countries and mitigation strategies for OTA reduction. Keywords: ochratoxin A; coffee; mycotoxin; threads; treatment 1. Coffee as a Unique Beverage Coffee is one of the most popular beverages nowadays all over the world, with an annual global production of 10.4 106 tons and it plays an important cultural and economic role [1]. It contains × more than 1500 chemical components, being responsible for sensorial and functional properties of the coffee beverage, the second most valuable legally traded commodity [2–4]. A recent study by Samoggia et al. (2018) indicated that consumers’ preferences for a specific coffee type mainly depended on sensory aspects like taste and aroma and functional motives to improve alertness and physical performance, beside habits and traditions of the consumer [5]. Coffee can be consumed as a hot or cold beverage, usually as the result of an infusion of properly processed coffee beans, being consumed per se as part or as the last component of meals or as an ingredient in snacks. It is, generally, produced from two biologically dissimilar species the Coffea arabica and Coffea canephora var. robusta, representing 60% and 40%, respectively, of world production [6]. Coffee from Coffea arabica (Arabica) and Coffea canephora var. robusta (Robusta) have several differences not only in terms of botanical, genetic, and morphological features of bean but also in their chemical composition and environmental conditions [7]. For example, while Arabica is adapted to lower temperatures and reduced humidity characteristics of high altitudes, Robusta is cultivated from sea level up to 1000 m; caffeine concentration endogenously present in the green coffee extracts of Robusta, often, is double that of Arabica, being dependent also of geographical origin and producing a drink with pronounced bitterness [6,7]. The tocopherols contents of Arabica are higher than Robusta and while 90% of tocopherols remain after roasting in the case of Arabica, a degradation of approximately 25% is observed for β-tocopherol in Robusta [8]. Recently, it was reported that the roasting procedure affected differentially coffee varieties in what concerns to antimutagenic activity, while no effect was observed in Robusta varieties, roasting enhances time-dependently the antimutagenicity of the Brazil variety (Arabica) [9]. Coffee is a unique beverage with healthy properties that make it a functional food due to its content in chlorogenic acids, caffeine, trigonelline, diterpenes and tocopherols present in raw Beverages 2019, 5, 36; doi:10.3390/beverages5020036 www.mdpi.com/journal/beverages Beverages 2019, 5, x FOR PEER REVIEW 2 of 15 BeveragesTherefore,2019, 5, 36 the coffee extracts exhibited free radical scavenging and induced detoxification2 of enzymes 14 [9,10]. Additionally, beneficial effects of coffee such as anti-mutagen, inductor of the activation of beans.DNA Therefore, repair, the as cowellffee as extracts in the decrease exhibited of free mortality radical from scavenging neurological and inducedand cardiovascular detoxification diseases, enzymesand [9 ,diabetes10]. Additionally, type II has beneficial been repo effectsrted of [10,11]. coffee such Despite as anti-mutagen, the literatur inductore support of the the activationrole of coffee as of DNAhaving repair, an as immunomodulatory well as in the decrease action, of mortality it seems fromto be neurologicaldisease-specific and [11]. cardiovascular diseases, and diabetesRecently, type II hasa study been investigated reported [10 the,11]. hypothesis Despite the that literature habitual support coffee consumption the role of co ffisee associated as havingwith an immunomodulatory lower risk of frailty, action, physical it seemsfunction to beimpairment, disease-specific and disability [11]. in women with aged 60 years Recently,or older a [12]. study The investigated conclusion the was hypothesis that habitual that coffee habitual consumption coffee consumption of two or ismore associated cup of withcoffee/day, lower riskin older of frailty, people, physical was not function associated impairment, with increased and disability risk of in functional women with impairment, aged 60 yearsand it or can be older [positive12]. The in conclusion the case of was individuals that habitual with codiabetes,ffee consumption hypertension of or two obesity or more [12]. cup of coffee/day, in older people, was not associated with increased risk of functional impairment, and it can be positive 2. Ochratoxin A as a Coffee Contaminant in the case of individuals with diabetes, hypertension or obesity [12]. 2. Ochratoxin2.1. Ochratoxin A as a CoA ffee Contaminant The mycotoxin ochratoxin A (OTA) is a low molecular weight ubiquitous secondary metabolite, 2.1. Ochratoxin A a weak organic acid consisting of an amino acid phenylalanine and a dihydro-isocoumarin linked by Thea peptide mycotoxin bond ochratoxin (Table 1). A (OTA) is a low molecular weight ubiquitous secondary metabolite, a weak organic acid consisting of an amino acid phenylalanine and a dihydro-isocoumarin linked by a peptide bond (Table1).Table 1. Structure, formula and physical characteristics of ochratoxin A (OTA). Table 1. Structure, formula and physical characteristics of ochratoxin A (OTA). Name N-[(5-chloro-3,4-dihydro-8-hydroxy-3-methyl-1-oxo-1H-2-benzopyran- Reference N-[(5-chloro-3,4-dihydro-8-hydroxy-3-methyl-1-oxo-17-yl)carbonyl]-L-phenylalanine H- Name Reference 2-benzopyran-7-yl)carbonyl]-l-phenylalanine ChemicalChemical structure structure Formula C20H18ClNO6 [13] MolecularFormula weight 403.8C20 gHmol18ClNO1 6 [13] [13] · − Molecular weight 168–173 ◦C (drying403.8 for g·mol 1 hour−1 at 60 ◦C) [14] [13] Melting point 159 ◦C (recrystallized168–173 °C (drying from for benzene-hexane) 1 hour at 60 °C) [15] [14] 169 C (recrystallized from xylene) [16] 159 ◦°C (recrystallized from benzene-hexane) [15] Melting21 point [α] D 46.8◦ (c = 2.65 mmol/L in chloroform) [14] 20 − 169 °C (recrystallized from xylene) [16] [α] D 118◦ (c = 1.1 mmol/L in chloroform) [16] − 3 1 1 [α]21D 214 nm−46.8° (" = (c37.2 = 2.65 mmol/L10− L molin chloroform)− cm− ) [14] × 3 · 1· 1 282 nm (" = 0.89 10− L mol− cm− ) λmax × 3 · 1 · 1 [14] 20 332 nm (" = 6.33 10 L mo cm ) [α] D −118° (c = 1.1 mmol/L× − in chloroform)· − · − [16] (c = 0.0281 mmol/L in methanol) pKa 4.2–4.4 and 7.0–7.3 [17] 214 nm (ε = 37.2 × 10−3 L.mol−1·cm−1) 282 nm (ε = 0.89 × 10−3 L.mol−1·cm−1) OTA is a whiteλmax crystalline, odorless, solid compound with poor aqueous solubility, but moderately[14] 332 nm (ε = 6.33 × 10−3 L.mo−1·cm−1) soluble in chloroform, methanol, ethanol and(c = xylene. 0.0281 mmol/L It is heat-stable, in methanol) being described as the most common member in group of ochratoxins [18,19]. The group of ochratoxins is principally formed by OTA, ochratoxinpKa B (OTB) and ochratoxin C4.2–4.4 (OTC). and From 7.0–7.3 a chemical perspective, while OTA[17] is chlorinated, ochratoxin B is not chlorinated, and ochratoxin C is the ethyl ester of OTA [18]. Although OTA appear to be overall the most toxic, from recent investigations a different and more detailed OTA is a white crystalline, odorless, solid compound with poor aqueous solubility, but picture have resulted with cell models showing in lower or similar toxicity of OTB compared to OTA; moderately soluble in chloroform, methanol, ethanol and xylene. It is heat-stable, being described as while there seems no doubt that OTB is less toxic in vivo compared to OTA, similar acutely cytotoxic the most common member in group of ochratoxins [18,19]. The group of ochratoxins is principally in vitro is observed. Meanwhile OTC seems to be equally acutely toxic in vivo and in vitro compared formed by OTA, ochratoxin B (OTB) and ochratoxin C (OTC). From a chemical perspective, while to OTA [20]. Nowadays, based on the metabolism of animals and humans, the number of molecules Beverages 2019, 5, x FOR PEER REVIEW 3 of 15 OTA is chlorinated, ochratoxin B is not chlorinated, and ochratoxin C is the ethyl ester of OTA [18]. Although OTA appear to be overall the most toxic, from recent investigations a different and more detailed picture have resulted with cell models showing in lower or similar toxicity of OTB comparedBeverages 2019 to, 5 ,OTA; 36 while there seems no doubt that OTB is less toxic in vivo compared to OTA,3 of 14 similar acutely cytotoxic in vitro is observed. Meanwhile OTC seems to be equally acutely toxic in vivo and in vitro compared to OTA [20]. Nowadays, based on the metabolism of animals and humans,belonging the to number this group of molecules has increased belonging substantially, to this group especially has onincreased OTA derivatives. substantially, Examples especially of thison OTAare hydroxylated, derivatives. Examples conjugated of this or metabolites are hydroxylated, where phenylalanineconjugated or metabolites moiety is absent where [ 21phenylalanine].