Michael G. Kontominas

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).

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.

Morphological characteristics, oxidative stability and enzymic hydrolysis of amylose-fatty acid complexes

Complexes of amylose with fatty acids varying in carbon chain length and degree of unsaturation were prepared at 30, 50 or 70°C by dissolving amylose in 0.1N KOH and mixing with fatty acid potassium soap solution. The complexes were obtained in solid form as precipitates after neutralization. SEM microscopy revealed that the morphology of the complexes was that of ordered lamellae separated from amorphous regions whereas confocal laser scanning microscopy showed images of the topography of the guest molecules in the complex matrix. FTIR spectroscopy revealed that the absorption peak attributed to carbonyl group of free fatty acid was shifted when the fatty acid was in the form of amylose complex. Thermo-gravimetry showed that the unsaturated fatty acids were effectively protected from oxidation when they were complexed with amylose whereas enzymic hydrolysis experiments showed that the guest molecules were quantitatively released from the amylose complexes.

Effect of chemical composition on physico-chemical, rheological and sensory properties of spreadable processed whey cheese

Abstract Pasteurised processed cheese spreads of varying chemical composition were developed, using a Myzithra-type cheese, which is a high-moisture and low-fat fresh whey cheese. Nine novel, spreadable processed whey cheese (PWC) samples were prepared comprising only of whey proteins, while guar gum was added as a stabiliser. All samples had a pH value of 5.20, which was obtained with the addition of a starter culture. The effect of chemical composition on the physico-chemical and rheological properties of PWC samples was studied. Due to their texture, two instrumental techniques, lubricated squeezing flow viscometry and texture profile analysis, were considered appropriate for the evaluation of samples. The decrease in protein content or the increase in fat content produced less viscous, consistent and solid samples, which were more spreadable. Protein content was shown to be a better predictor of the texture of PWC samples. Sensory assessments revealed that the majority of PWC samples had good spreadability and flavour and were rated as highly acceptable. Results of sensory and instrumental analyses were highly positively correlated. Results have shown that the choice of the desired formulation could be manipulated for the production of processed whey cheese spreads with specific properties.