Flavour analysis of Greek white wine by solid-phase microextraction-capillary gas chromatography-mass spectrometry

Solid-phase microextraction (SPME) was optimised for the qualitative determination of the volatile flavour compounds responsible for the aroma of Greek Boutari wine. Several factors influencing the equilibrium of the aroma compounds between the sample and the SPME fiber were taken into account, including the extraction time, the extraction temperature, the sampling mode (headspace and direct immersion or liquid SPME), and the presence of salt. Four different SPME fibers were used in this study. namely poly(dimethylsiloxane) (PDMS), poly(acrylate), carbowax-divinylbenzene and divinylbenzene-carboxen on poly(dimethylsiloxane). The best results were obtained using the PDMS fiber during headspace extraction at 25 degrees C for 30 min after saturating the samples with salt. The optimised SPME method was then applied to investigate the qualitative aroma composition of three other Greek wines, namely Zitsa, Limnos and Filoni.     

Solid state polymerization of poly(lactic acid): Some fundamental parameters

Poly(lactic acid) (PLA) was submitted to solid state polymerization (SSP) in a fixed bed reactor under nitrogen flow, so as to examine technique efficiency for increasing the molecular weight and hence permitting the reduction of the melt polymerization residence times. In order to use a suitable starting material, SSP prepolymers of low and medium molecular weight were first prepared through solid state hydrolysis of commercial PLA grade under acidic and alkaline conditions. During these degradation runs, hydrolysis involved the random scission of ester groups in the polymer backbone, while the relevant kinetics and the resulting thermal properties were also examined. In a subsequent step, the prepolymers obtained were subjected to SSP at three temperatures, approximately 2.5–25.0 °C below their melting point. The process achieved an increase of up to 1.7 times the initial molecular weight, however, with different trends depending on the prepolymer characteristics, reaction temperature and time, as well as the pH of the hydrolysis medium. In addition to molecular weight build up, the effect of the SSP process on end product thermal properties was also investigated.     

Differentiation of young red wines based on cultivar and geographical origin with application of chemometrics of principal polyphenolic constituents

Nineteen major polyphenolic phytochemicals including hydroxycinnamate derivatives, flavanols, flavonols, and anthocyanins, were determined in 40 experimental red wines employing HPLC-DAD. All wines analysed were young (non-aged), produced, and stored under identical conditions, in an effort to minimize the effect of oak wood and vinification technology. The data obtained from this examination composed the matrix for the implementation of chemometrics, which aimed at differentiating the wine samples on the basis of cultivar and geographical region of origin. Discriminant analysis performed at a 95% significance level revealed a very satisfactory categorization of the samples both in terms of cultivar and region of origin, thus illustrating the validity of major phenolic phytochemicals for studies pertaining to wine quality and authenticity.     

Characterization of Greek Wines by Ultraviolet–Visible Absorption Spectroscopy and Statistical Multivariate Methods

Optical absorption spectroscopy has been used to study Cretan Greek wine matured for 3 months in various barrels. Vilana and Dafni white and Kotsifali and Mandilari red wines were analyzed. The total phenolic index for all varieties and color characteristics for only the red wine were determined. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) demonstrated that the absorption spectra, combined with multivariate statistical methods, may be used to identify these varieties. The results of principal component analysis were used to infer the chemical compounds responsible for the discrimination between varieties.