Study On The Effect Of Sulfur Dioxide And Glutathione Changes On Wine Color Under The Action Of Ultrasound

In recent years,as a non-thermal processing technology,ultrasound treatment is regarded to have great potential in accelerating wine ageing.Studies showed ultrasound treatment changed wine components and modified wine color,while the reaction mechanism remains unknown.Sulfur dioxide(SO2)and reduced glutathione(GSH)are important sulfur compounds in wine,the changes of which play an important role in wine color.This study concentrated on SO2 and GSH.Uv-vis spectrophotometer,HPLC,HPLC-MS,EPR was applied to investigate the effects of ultrasound treatment on wine color,SO2,GSH and main pigment(anthocyanin and xanthylium ion),and to analyze their correlations.The mechanism of changes in SO2 and GSH under ultrasound treatment and the influence in wine color was studied to provides a reference for the application of ultrasound in wine industry.The main reults of this study are discussed as follows:1.To investigate the effects of ultrasound condition on SO2 and wine color,different ultrasound treatment i.e.ultrasonic temperature(15?,30?,45?),ultrasonic power(150 W,300 W,450 W)and ultrasonic time(10 min,30 min,50 min)were applied in wine.Results show that different ultrasonic temperature,power and time have significant effects on color of wine,free SO2 content and total SO2 content of wine,but had no significant effects on color hue,red%,Blue%and yellow%.Compared with untreated samples,ultrasound treatment improved the color properties of wine,reduced SO2 content,and modified the quality of wine.Response surface analysis was conducted to obtain the best ultrasound treatment parameters.For practical reason,the applied ultrasound treatment parameters were as follows:ultrasound frequency was 59 kHz,ultrasound power was 260 W,ultrasound treatment time was 39 min,treatment temperature was 45?.Considering the changes in copigment after ultrasound treatment set in above parameters,the copigmentation propertied and the content in wine,gallic acid was selected as the copigment of model wine.PCA results show that the content of free SO2 and total SO2 in wine are positively correlated with color hue,but negatively correlated with wine color,browning index and color density.2.For further study on the effects and mechanism of ultrasound treatment on SO2 and wine color,a model wine system containing SO2,cyanindin-3-glucoside and gallic acid was established.Results show that ultrasound treatment improved the color properties of model wine.The evolution of SO2 and gallic acid after ultrasound treatment during storage are similar to those in untreated one,and ultrasound treatment accelerates these changes.Moreover,ultrasound treatment promotes the oxidation of SO2 into SO42-,and inhibited the color protection of SO2.Ultrasound treatment can destroy colorless adduct and release cyanidin-3-glucoside,meanwhile promote the copigmentaion of cyanidin-3-glucoside,and modified the color of model wine.PCA results show that in both ultrasound treated model wine and untreated one,wine color and color density are positively correlated with Red%,while negatively correlated with free SO2 and gallic acid.Generally,ultrasound treatment can improve the color properties of model,while not change the correlations among wine color,color density,Red%and free SO2 as well as gallic acid.3.Xanthylium ion compounds are the main oxidized pigment occurring during wine storage,stemmed from(+)-catechin and tartaric acid.To study the effects and mechanism of ultrasound on wine oxidized coloration,a model wine system containing GSH,(+)-catechin and tartaric acid was established.Results show that ultrasound treatment inhibited the color protection of GSH,and promoted oxidized coloration.The evolution of GSH,(+)-catechin and xanthylium ion after ultrasound treatment during storage are similar to those in untreated one,and ultrasound treatment accelerates the changes in(+)-catechin and xanthylium ion,while the effects on GSH is not significant.EPR results indicate that ultrasound reduce the formation of 1-hydroxyethyl radicals generated and enhance the intensity,subsequently promotes the reaction between(+)-catechin and tartaric acid and accelerated the formation of xanthylium ion pigments and its precuesor,as wel as modified wine color.In conclusion,ultrasound treatment can promote the formation of pigments in model wine during storage,while reducing unpleasant odor and SO2,and improve the quality of wine.In summary,ultrasound treatment can inhibited the color protection of SO2 and GSH,accelerate the color formation in wine,and reduce the content of SO2.Moreover,ultrasound treatment can induce the formation of 1-hydroxyethyl radical,and promote the formation of xanthylium ions as well as acceletate wine ageing.