ABSTRACT
In this work a comparative assessment was performed on individual and total polyphenols and biochemical properties of some Feteasca Neagra red wines obtained from grapes cultivated with different farming technologies (organic vs. conventional). The effect of a 30% cluster thinning treatment in both organic and conventional vineyard, compared to control plots with no thinning, was also monitored. The wines were obtained during two vintages, one with more favourable climatic conditions and one less favourable, in the period 2010-2019. Our results indicate that by applying a 30% cluster thinning treatment in the vineyard it is possible to increase the concentration of total and individual polyphenols of the resulted Feteasca Neagra wines. Furthermore, the differences observed between the phenolic profiles of wines from conventionally and organically produced grapes showed that organic Feteasca Neagra wines have higher phenolic compounds concentrations and antioxidant properties, with some important individual phenols accumulating in larger quantities than in the case of conventional wines. The beneficial effect of the organic cultivation is more evident in years characterised by less favourable climatic conditions. The statistical analysis tools applied to the analytical data allowed a good discrimination of experimental wine variants according to the vine cultivation technology (organic vs. conventional, with and without cluster thinning) and vintage. Thus, the results indicated that the applied cultivation technologies, especially when both organic cultivation and cluster thinning are combined, can greatly improve the polyphenolic content of Feteasca Neagra wines. The absolute value of the increase in polyphenol concentration was higher in favourable years, but the relative increase, in percentages, as compared to control wines, was higher in less favourable years. The combination of both viticultural practices may be thus exploited in order to obtain wines with higher polyphenolic content, which leads to better structure, better ageing potential, enhanced nutritional and antioxidant properties.
ABSTRACT
Volatile profiles were determined for white wines of Feteasca regala variety produced from musts in which the antioxidants glutathione and ascorbic acid were added in different proportions before inception of alcoholic fermentation. Treatments with these antioxidants affect some volatile compound evolution and positively influence the wine volatile profile. After one year of storage in bottles with and without carbon dioxide protection the volatile profiles of the wines were assessed by using a Fast GC Alpha MOS Heracles e-Nose by applying a DFA multivariate statistical method and AroChemBase database for compound identification. The analyses showed that some higher alcohols, such as 2-phenylethanol and 2-methyl-1-butanol were in lower concentrations in wines treated with reduced glutathione, while the main ethyl fatty acid esters, such as ethyl butanoate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate were better preserved when higher concentrations of any of the antioxidants were added in must. On the other hand, it was observed that some other volatile compounds were not affected by these applied treatments.
