Quality Assessment of Raw Honey Issued from Eastern Romania
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agriculture Article Quality Assessment of Raw Honey Issued from Eastern Romania Aida Albu, Cristina-Gabriela Radu-Rusu *, Ioan Mircea Pop *, Gabriela Frunza and Gherasim Nacu Animal Science Faculty, “Ion Ionescu de la Brad” University of Agricultural Sciences and Veterinary Medicine, 8 Mihail Sadoveanu Alley, 700489 Iasi, Romania; [email protected] (A.A.); [email protected] (G.F.); [email protected] (G.N.) * Correspondence: [email protected] (C.-G.R.-R.); [email protected] (I.M.P.) Abstract: Romania is known among the main European honey producers, due to the variety of landforms as well as the diversity of the flora. Thirty-four honey samples of the acacia, linden and multifloral types, produced in eastern Romania and collected during 2013–2018, were physico- chemically analyzed using methods provided by the national and EU standards. The results of water-insoluble solids, color and refractive index were found to be 0.023–0.131%, 0.3–76.4 mm Pfund and 1.485–1.499, respectively. The moisture content ranged between 15.20% and 20.77%, solid substances content ranged between 79.23% and 84.80% and total soluble substances content ranged between 77.83 ◦Brix and 83.26 ◦Brix. The obtained values of specific gravity were from 1.414 to 1.450 g/cm3, pH ranged from 3.673 to 5.503 and free acidity ranged between 2.4 meq and 50 meq kg−1. The ash content and the electrical conductivity varied between 0.030 and 0.543% and 130 and 679 µS cm−1, respectively. Pearson0s correlation analysis showed an intense association of the ash content with electrical conductivity (r = 0.81). Our findings reveal the qualitative level of Romanian honey and the variation in quality parameters due to factors such as geographical region, Citation: Albu, A.; Radu-Rusu, C.-G.; climatic conditions, botanical origin and handling or storage conditions. Pop, I.M.; Frunza, G.; Nacu, G. Quality Assessment of Raw Honey Keywords: raw honey; conductivity; specific gravity; total soluble substances; refractive index; quality Issued from Eastern Romania. Agriculture 2021, 11, 247. https:// doi.org/10.3390/agriculture11030247 1. Introduction Academic Editors: Gianluca Caruso, Honey is known and recognized as a wholesome food consumed due to its extraor- László Baranyai and Vasile Stoleru dinary composition, in terms of nutritional and therapeutic features [1,2]. Honey was Received: 31 January 2021 considered to have healing properties by the ancient civilizations going back in time from Accepted: 3 March 2021 the Chinese Empire to the Egyptian Empire. Nowadays, it is quite a trend to investigate Published: 14 March 2021 alternative natural foods and molecules, such as bee products, which have been supposed to trigger active pharmacologic and metabolic pathways and to generate beneficial effects Publisher’s Note: MDPI stays neutral on consumers’ health. [3]. with regard to jurisdictional claims in Romania has an ancient tradition of beekeeping and now is one of the most important published maps and institutional affil- honey producers in Europe, due to the variety of landforms as well as the diverse and very iations. rich flora. In the Romanian flora, there is a series of species of honey plants that stand out through a high honey production. This country has potential to offer sufficient and variate botanical resources to the indigenous bees (Apis mellifera carpatica) in order to obtain a wide panel of unifloral and multifloral honeys, such as the linden (Tilia tomentosa) type, the Copyright: © 2021 by the authors. acacia sort (Robinia pseudoacacia), the sunflower variety (Helianthus anuus) and, of course, Licensee MDPI, Basel, Switzerland. the multifloral type (usually from spring–summer meadows and grasslands). North East This article is an open access article Romania, specifically the historical province of Moldova, is known as the largest linden distributed under the terms and massive [4–6]. From the mountains to the plains, the eastern region of Romania is rich in conditions of the Creative Commons cultivated and spontaneous polliniferous and nectariferous plants. Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Agriculture 2021, 11, 247. https://doi.org/10.3390/agriculture11030247 https://www.mdpi.com/journal/agriculture Agriculture 2021, 11, 247 2 of 17 Agriculture 2021, 11, x FOR PEER REVIEW 2 of 17 This food contains many important constituents such as sugars, acids, proteins, vita- mins,the development enzymes and of micro-yeasts and macro-elementsavoiding fermen [tative7]. The processes. low water Yeast inner and content mold is prolifer- among theation most in honey important could traits be regulated with relevance by the free in maintaining acidity and honeywater content freshness, within stopping [8]. Both the developmentelectrical conductivity of yeasts and and crude avoiding ash fermentativeanalyses are processes.frequently used Yeast in and honey mold quality prolifera- in- tionspections. in honey Those could traits, be especially regulated electrical by the free conductivity, acidity and are water considered content very within good [8 ].criteria Both electrical conductivity and crude ash analyses are frequently used in honey quality inspec- for assessment of the botanical origin and purity of honey [9]. Legislation has established tions. Those traits, especially electrical conductivity, are considered very good criteria for maximum allowed values for some parameters, such as a maximum 20% moisture con- assessment of the botanical origin and purity of honey [9]. Legislation has established tent, maximum 50 meq kg−1 free acidity, maximum acceptable content of water-insoluble maximum allowed values for some parameters, such as a maximum 20% moisture content, solids no more than 0.1% and no more than 0.5% for pressed honey and a maximum per- maximum 50 meq kg−1 free acidity, maximum acceptable content of water-insoluble solids mitted value of 0.8 µS cm−1 conductivity for nectar honey, with the exception of chestnut no more than 0.1% and no more than 0.5% for pressed honey and a maximum permitted honey which should be not less than 0.8 µS cm−1 [10,11]. Such physical and chemical traits value of 0.8 µS cm−1 conductivity for nectar honey, with the exception of chestnut honey are keystones on the way to assess honey quality and to identify its authenticity and which should be not less than 0.8 µS cm−1 [10,11]. Such physical and chemical traits are origin. All honey parameters are correlated twice. Many studies have shown that the var- keystones on the way to assess honey quality and to identify its authenticity and origin. iation in one parameter leads to the modification of the other parameters such as ash and All honey parameters are correlated twice. Many studies have shown that the variation in oneelectrical parameter conductivity leads to theand modificationrefractive index of the with other specific parameters gravity such and as total ash andsoluble electrical sub- conductivitystances. and refractive index with specific gravity and total soluble substances. In this work, studies were carried out to show the high quality of Romanian honey, quality that remains high regardless ofof thethe geographicalgeographical areaarea andand yearyear ofof harvest.harvest. 2. Materials and Methods Thirty-four raw honey samples produced byby Apis mellifera of three of the most known honey types: acacia (A) (twelve samples), lin lindenden (L) (ten samples) and multifloralmultifloral (M) (twelve samples), were collectedcollected duringduring 2013–20182013–2018 directly fromfrom beekeepers.beekeepers. The honey produced inin easterneastern RomaniaRomania comes comes from from different different sites sites of of Iasi, Iasi, Vaslui Vaslui and and Suceava Suceava counties coun- (Figureties (Figure1a,b). 1a,b). The collectionThe collection of honey of honey samples samples was carried was carried on throughout on throughout different different years, fromyears, 2013 from to 2013 2018, to during 2018, during the period the period of maximum of maximum flowering flowering of melliferous of melliferous plants (acaciaplants and(acacia linden). and linden). Raw honey Raw sampleshoney samples were kept were in glasskept in jars, glass preserved jars, preserved at room at temperature room tem- (20perature± 3 ◦ C),(20 away± 3 °C), from away light. from The light. analyses The analyses were performed were performed within a within maximum a maximum of 2 weeks of from2 weeks the from arrival the ofarrival the samples of the samples to avoid to theiravoid degradation their degradation as well as as well the as modification the modifi- ofcation their of parameters, their parameters, taking taking into account into accoun the factt the that fact they that werethey were raw honeyraw honey samples samples and notand commercialnot commercial honey. honey. The analysesThe analyses were were performed performed in triplicate. in triplicate. The crystallizedThe crystallized raw ◦ honeyraw honey samples samples were were liquefied liquefied at 40 atC in40 a°C water in abath water (manufacturer: bath (manufacturer: Memmert Memmert GMBH –GMBH Schwabach, – Schwabach, Germany). Germany). Homogenized Homogenized samples samples were filtered were filtered through through a double-layered a double- gauzelayered to gauze retain to the retain biggest the impuritiesbiggest impurities prior to theprior analysis. to the analysis. (a) (b) Figure 1. (a) Locations of honey production; (b) year, typetype andand locationlocation ofof studiedstudied honeyhoney samples.samples. 2.1. Water-Insoluble Solids The gravimetric method was applied to assess the water-insoluble solids (WIS). Ten grams of the homogenized honey sample was weighed on the PI-214 DENVER analytical scales (manufacturer: Denver Instrument GMBH – Gottingen, Germany). Prior to filtering through a qualitative-type filter paper adjusted prior to constant mass, the sample was Agriculture 2021, 11, 247 3 of 17 2.1. Water-Insoluble Solids The gravimetric method was applied to assess the water-insoluble solids (WIS). Ten grams of the homogenized honey sample was weighed on the PI-214 DENVER analytical scales (manufacturer: Denver Instrument GMBH – Gottingen, Germany).