Stavros Kontakos

Characterisation and classification of Greek pine honeys according to their geographical origin based on volatiles, physicochemical parameters and chemometrics.

The aim of the present study was to characterise and classify Greek pine honeys according to geographical origin, based on the determination of volatile compounds and physicochemical parameters using MANOVA and Linear Discriminant Analysis. Thirty-nine pine honey samples were collected during the harvesting period 2011 from 4 different regions in Greece known to produce good quality pine honey. The analysis of volatile compounds was performed by Headspace Solid Phase Microextraction-Gas Chromatography/Mass Spectroscopy. Fifty-five volatile compounds were tentatively identified and semi quantified. Physicochemical parameter analysis included the determination of pH, free, lactonic and total acidity, electrical conductivity, moisture, ash, lactonic/free acidity ratio and colour parameters L(∗), a(∗), b(∗). Using 8 selected volatile compounds and 11 physicochemical parameters, the honey samples were satisfactorily classified according to geographical origin using volatile compounds (84.6% correct prediction), physicochemical parameters (79.5% correct prediction) and the combination of both (74.4% correct prediction).

Characterization and classification of Western Greek olive oils according to cultivar and geographical origin based on volatile compounds.

The aim of the present study was to characterize and classify olive oils from Western Greece according to cultivar and geographical origin, based on volatile compound composition, by means of Linear Discriminant Analysis. A total of 51 olive oil samples were collected during the harvesting period 2007-2008 from six regions of Western Greece and from six local cultivars. Forty-five of the samples were characterized as extra virgin olive oils. The analysis of volatile compounds was performed by Headspace Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (HS-SPME-GC/MS). Fifty-three (53) different volatile compounds were tentatively identified and semi-quantified. Using selected volatile compound composition data (selection was based on the application of ANOVA to total volatiles to determine those variables showing substantial differences among samples of different geographical origin/cultivar), the olive oil samples were satisfactorily classified according to geographical origin (87.2%) and cultivar (74%).

Botanical discrimination of Greek unifloral honeys with physico-chemical and chemometric analyses

The aim of the present study was to investigate the possibility of characterisation and classification of Greek unifloral honeys (pine, thyme, fir and orange blossom) according to botanical origin using volatile compounds, conventional physico-chemical parameters and chemometric analyses (MANOVA and Linear Discriminant Analysis). For this purpose, 119 honey samples were collected during the harvesting period 2011 from 14 different regions in Greece known to produce unifloral honey of good quality. Physico-chemical analysis included the identification and semi quantification of fifty five volatile compounds performed by Headspace Solid Phase Microextraction coupled to gas chromatography/mass spectroscopy and the determination of conventional quality parameters such as pH, free, lactonic, total acidity, electrical conductivity, moisture, ash, lactonic/free acidity ratio and colour parameters L, a, b. Results showed that using 40 diverse variables (30 volatile compounds of different classes and 10 physico-chemical parameters) the honey samples were satisfactorily classified according to botanical origin using volatile compounds (84.0% correct prediction), physicochemical parameters (97.5% correct prediction), and the combination of both (95.8% correct prediction) indicating that multi element analysis comprises a powerful tool for honey discrimination purposes.

Effect of packaging material on enological parameters and volatile compounds of dry white wine

The enological parameters and volatile compounds of white wine packaged in dark coloured glass and two commercial bag-in-box (BIB) pouches (low density polyethylene - LDPE and ethylene vinyl acetate - EVA lined) were determined for a period of 6 months at 20 °C. Parameters monitored included: titratable acidity, volatile acidity, pH, total SO2, free SO2, colour, volatile compounds and sensory attributes. The BIB packaging materials affected the titratable acidity, total and free SO2 and colour of wine. A substantial portion of the wine aroma compounds was adsorbed by the plastic materials or lost to the environment through leakage of the valve fitment. Between the two plastics, the LDPE lined pouch showed a considerably higher aroma sorption as compared to EVA. Wine packaged in glass retained the largest portion of its aroma compounds. Sensory evaluation showed that white wine packaged in both plastics was of acceptable quality for 3 months vs. at least 6 months for that in glass bottles.

Characterization of Four Popular Sweet Cherry Cultivars Grown in Greece by Volatile Compound and Physicochemical Data Analysis and Sensory Evaluation

Volatile compounds, physicochemical and sensory attributes of four sweet cherry cultivars (Canada giant, Ferrovia, Lapins and Skeena) grown in Northern Greece were determined. Eighteen volatile compounds were identified and semi-quantified in cherries using solid phase micro extraction in combination with gas chromatography/mass spectrometry (SPME-GC/MS). Carbonyl compounds were the most abundant in sweet cherry aroma, followed by alcohols, esters and hydrocarbons/terpenes. Cherry cultivars in order of increasing amounts of volatiles were: Lapins < Canada giant < Ferrovia < Skeena. Physicochemical parameters determined included: titratable acidity (TA), pH, total soluble solids (TSS), maturity index (MI) and total phenolic content (TPC). TA ranged between 0.21 and 0.28 g malic acid/100 g fresh weight (FW). The pH ranged between 3.81 and 3.96. TSS ranged between 13.00 and 16.00 °Brix. MI ranged between 51.8 and 75.0. TPC ranged between 95.14 and 170.35 mg gallic acid equivalents (GAE)/100 g FW. Sensory evaluation showed that cherry colour, in order of increasing intensity, was: Canada giant < Ferrovia < Lapins < Skeena. Respective order for cherry firmness was: Canada giant < Lapins ≤ Ferrovia < Skeena and for flavour: Lapins < Canada giant < Skeena ≤ Ferrovia. Correlation of volatiles to physicochemical and sensory attributes showed varying trends.

Characterization and classification of commercial thyme honeys produced in specific Mediterranean countries according to geographical origin, using physicochemical parameter values and mineral content in combination with chemometrics

The aim of the present study was to provide information on physicochemical (pH, free, lactonic, and total acidity, electrical conductivity, moisture, ash, lactonic/free acidity), colour parameters (L*, a*, b*), and mineral content (Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Se, Si, Ti, Tl, V, Zn) of 34 commercial thyme honeys produced in Egypt, Morocco, Greece, and Spain, in terms of characterization and geographical discrimination using MANOVA/LDA, chemometric analyses. Conventional physicochemical and colour parameters were determined using official methods of analysis. Minerals were quantified using inductively coupled plasma optical emission spectroscopy (ICP-OES). Results showed that all honey samples analysed met the standard quality criteria set by the EU. In order to classify honeys according to geographical origin, MANOVA and LDA were applied in sequence. Respective classification rates based on cross-validation method were: 91.2, 76.5, and 88.2%, using 10 physicochemical and colour parameters, 12 minerals, and their combination, respectively. Testing whether the determined physicochemical parameters of commercial Mediterranean thyme honeys could be applied to routine quality control serving as honey origin predictors showed positive results. Finally, such a combination of data enhances honey quality control and authentication efforts, at an international level.

Impact of physicochemical parameters, pollen grains, and phenolic compounds on the correct geographical differentiation of fir honeys produced in Greece as assessed by multivariate analyses

ABSTRACT In the present study, the effect of different parameters on the correct geographical differentiation of Greek fir honey was investigated. Forty-three honey samples were collected from four regions and subjected to physicochemical and melissopalynological analyses, using official and instrumental methods. Results showed that fir honeys met the European regulatory quality standards, whereas significant differences (p < 0.05) were recorded for all the determined parameters according to geographical origin. The highest differentiation rate (81.4%) was recorded using the combination of six physicochemical parameters and five phenolic compounds, as assessed by multivariate analyses.

Differentiation of Fresh Greek Orange Juice of the Merlin Cultivar According to Geographical Origin Based on the Combination of Organic Acid and Sugar Content as well as Physicochemical Parameters Using Chemometrics

The aim of the present study was to differentiate fresh Greek orange juice prepared from the Merlin cultivar according to geographical origin, based on organic acid/sugar content, and physicochemical parameter analysis, using chemometrics. For this purpose, oranges were collected during the harvesting period 2013–2014 from four different regions in Greece where Merlin oranges are produced. The analysis of organic acids and sugars was performed using a modified high pressure liquid chromatographic (HPLC–DAD/RI) method. Applying MANOVA and LDA analysis to the collected data, orange juices were successfully classified according to geographical origin (correct classification rate 83.3%). For validation purposes of the applied model, oranges from the harvesting period 2014–2015 were also collected and new instrumental and chemometric analysis carried out involving orange juice from both harvesting periods. Cumulative results showed that the classification rate remained practically constant, recording a correct classification rate of 80.4%, confirming the discriminatory power of the applied model. In order to further improve the overall classification rate, physicochemical parameter data were subjected to chemometric analysis along with organic acid and sugar content data. Results showed that the combination of organic acids, sugars, and physicochemical parameters somewhat increased the overall correct prediction rate to 82.0%. Present results enhance the potential of multi-parameter analysis for the correct geographical differentiation of Greek fresh orange juice, aiding to product quality and authenticity control.

Geographical discrimination of pine and fir honeys using multivariate analyses of major and minor honey components identified by 1 H NMR and HPLC along with physicochemical data

The objective of the present work was the geographical discrimination of the most common honeydew honeys produced in Greece, namely pine and fir, on the basis of sugar, free amino acid and organic acid content, determined by nuclear magnetic resonance spectroscopy (1H NMR) and high-performance liquid chromatography (HPLC), along with moisture content, sugar ratios, or sugars to moisture ratio, using chemometrics. For this purpose, 39 pine and 31 fir honey samples were collected from professional beekeepers from eight different regions in Greece. Data were subjected to multivariate analysis and modeled using supervised statistical methods. The combination of 1H NMR and HPLC based on metabolites along with the aforementioned physicochemical data resulted in the geographical discrimination of pine and fir honeys. Respective prediction rates were 76.9 and 80.6%, using a model validation technique: the cross-validation method. Present results support the combined use of instrumental and conventional methods for honey geographical origin differentiation.

Volatile fraction of commercial thyme honeys produced in Mediterranean regions and key volatile compounds for geographical discrimination: A chemometric approach

ABSTRACT The aim of the present study was to investigate the volatile fraction and discriminate 34 commercial thyme honeys from Morocco, Egypt, Spain, and Greece according to geographical origin, using key volatile compounds in combination with chemometrics. Sixty-two volatile compounds belonging to different classes were identified and semi-quantified using headspace solid phase micro-extraction coupled to gas chromatography/mass spectrometry (HS-SPME-GC/MS). Applying chemometric analyses to 17 volatiles (p < 0.05), honeys were successfully discriminated according to geographical origin. Correct classification rate was 88.2% using the cross-validation method. Volatile compounds proved to be a powerful tool for discriminating commercial thyme honeys from different countries.