Natural alternatives of Sulphur dioxide used in wine and their effects on aromatic compounds

Abstract

Introduction. The aims of this study were to determine the effects of different natural plant extracts used as an alternative of Sulphur dioxide on wine aroma compounds. Materials and methods. The wine production was done according to the accepted conventional method of red wines (Cabernet Sauvignon). The experimental design was achieved by using different plant extracts (grape pomace, rosemary, black blueberry) at different concentrations. As the first control group was used wine samples processed without natural extracts and Sulphur dioxide treatments and as the second group was used wines produced with 25mg/L Sulphur dioxide addition. Results and discussion. The highest total amount of volatile compounds was achieved by applying blueberry extract and grape pomace extract. The combined application of Sulphur dioxide and blueberry extract increased the wine volatile complexity. The best results related to higher alcohols synthesis and their accumulation in wines was obtained by using Sulphur dioxide (25 mg/L) and plant extracts (0.3 mL). The terpenes were dominated by geraniol. The highest value was obtained in sample treated with grape pomace. The ester fraction was represented by 9 identified compounds. The highest total ester content (169.13 mg/L) was found in sample obtained with combined treatment of 25 mg/L Sulphur dioxide and rosemary extract 0.3 mL. The other three variants of rosemary treatments demonstrated quantitatively close ester content. In samples containing grape pomace extract was found the lowest total ester content compared to all others. From this group, only sample including25 mg/L Sulphur dioxide and grape pomace extract 0.3 mL (40.62 mg/L) was distinguished. Methyl alcohol was found in all tested wines. The methyl alcohol levels were very low and not pose a risk to the consumer. Conclusions. The study demonstrated the possibilities of optimization of Sulphur dioxide by using natural plant extracts.