Profiling Turkish Honeys to Determine Authenticity Using Physical and Chemical Characteristics

Abstract

Seventy authentic honey samples of 9 different floral types (rhododendron, chestnut, honeydew, Anzer (thymus spp.), eucalyptus, gossypium, citrus, sunflower, and multifloral) from 15 different geographical regions of Turkey were analyzed for their chemical composition and for indicators of botanical and geographical origin. The profiles of free amino acids, oligosaccharides, and volatile components together with water activity were determined to characterize chemical composition. The microscopic analysis of honey sediment (mellissopalynology) was carried out to identify and count the pollen to provide qualitative indicators to confirm botanical origin. Statistical analysis was undertaken using a bespoke toolbox for Matlab called Metabolab. Discriminant analysis was undertaken using partial least-squares (PLS) regression followed by linear discriminant analysis (LDA). Four data models were constructed and validated. Model 1 used 51 variables to predict the floral origin of the honey samples. This model was also used to identify the top 5 variable important of projection (VIP) scores, selecting those variables that most significantly affected the PLS-LDA calculation. These data related to the phthalic acid, 2-methylheptanoic acid, raffinose, maltose, and sucrose. Data from these compounds were remodeled using PLS-LDA. Model 2 used only the volatiles data, model 3 the sugars data, and model 4 the amino acids data. The combined data set allowed the floral origin of Turkish honey to be accurately predicted and thus provides a useful tool for authentication purposes. However, using variable selection techniques a smaller subset of analytes have been identified that have the capability of classifying Turkish honey according to floral type with a similar level of accuracy.

PCA: The Basic Building Block of Chemometrics

“…The chemical composition of honey is studied and known to a large extent for nearly 50 years. The presence of compounds beneficial to health for their antioxidant properties or for other reasons is well known, this is the case of polyphenols [68][69][70][71][72][73][74] or amino acids [75][76][77][78][79][80][81][82][83], some of them are good fluorophores like polyphenols. Works evoke the interest of using these fluorophores as tracers of the floral origin of honeys.…”

Characterization and Geographical Classification of Greek Fir Honeys Based on Physicochemical Parameters, Colour Attributes, and Volatile Compounds Using Chemometrics

“…Numerous of these compounds including: 2-ethyl-1-hexanol, 1-octanol, 1-nonanol, furfural, benzaldehyde, octanal, decanal, benzeneacetaldehyde, heptane, 1-octene, octane, nonane, 2,5-dimethyl-furan, borneol, 3,4,5-trimethyl-phenol, have been identified in Greek and Turkish pine honeys [19,20] as well as in fir honeys from Croatia [21]. What is remarkable is that, the ethyl esters identified in the present study, have not been reported previously in monofloral honeys produced in different countries [3,20,21,22]. These compounds are reported for the first time in fir honey, and may originate from resins secreted in Greek fir trees.…”

“…It should be stressed that, honey aroma, along with colour and taste, are among of the most important parameters affecting product acceptability by consumers. Furthermore, numerous volatile markers have been used for the determination of geographical and botanical origin of particular honey samples [2,3,4,20], using chemometrics. Table 3.IS: internal standard.…”

Modern analytical techniques in the assessment of the authenticity of Serbian honey / Moderne analitičke tehnike u procjeni izvornosti meda iz Srbije

“…An assessment of honey authenticity, especially determination of its botanical origin, based on the content of amino acids, has been the subject of a number of studies (60)(61)(62)(63)(64)(65)(66). Some of them emphasised that specific amino acid profile may be used for the assessment of honey authenticity (60)(61)(62), while other reports stated that such discrimination was incomplete and could be used for an unambiguous assignment only together with other parameters such as physicochemical ones, sugar and mineral content, etc.…”