Study On The Effect Mechanism Of Ultrasonic Treatment On The Color Change Of Red Wine During Storage

In recent years,ultrasound is considered to be a potential physical aging wine technology.Existing studies have shown that ultrasonic treatment can improve the color quality and stability of wines,but the mechanism of the effect of ultrasound on color of red wine is not yet clear,and whether the effects of ultrasound are long-term or irreversible is currently not studied.In this study,red wine was treated with ultrasound and the evolutions of color characteristics,main anthocyanins and phenolic compounds of the wine were investigated during storage,and their correlations were analyzed to explore the mechanism of ultrasonic influence on the coloration of red wine.In addition,in order to study the influence mechanism of ultrasound on copigmentation of anthocyanin in wine,an appropriate copigment was selected to add to the red wine,and then this wine was sonicated to investigate the evolutions of color characteristics,proportions of monomeric anthocyanins,copigmented anthocyanins and polymeric anthocyanins and the contents of anthocyanin and copigment of red wine during storage.The content and results of this paper are as follows:1.Effect of ultrasonic treatment on the evolution of red wine color properties was studied.The results show that ultrasound treatment can indeed improve the color of red wine.When wine was processed for 28 min with ultrasonic frequency of 20 kHz and ultrasonic power of 100 W,the color of red wine was improved most obviously.The changing trend of absorption spectrum,color parameters,main anthocyanins,and phenolic compounds of the sonicated wines were all similar to those of non-sonicated wines,and all indexes changed farster after treating by ultrasound.Specifically,ultrasonic treatment can increase the absorption value of visible absorption spectrum,enhance the color of wine,increase the color intensity and browning index,and increase the contribution rate of red component in wine to the color intensity of wine.What's more,the effect of ultrasound on the enhancement of red wine is irreversible,not having a "back to raw" phenomenon.2.Effect of ultrasonic treatment on the evolution of main anthocyanins and phenolic compounds in red wine was investigated.The evolutions of malvidin-3-O-glucoside,(+)-catechin,caffeic acid,syringic acid,(-)-epicatechin,and gallic acid with storage time are similar both in ultrasonic treated wine and ultreated wine.Moreover,it is noteworthy that ultrasound treatment can accelerate these changing.According to the results of principal component analysis,in both ultrasonic treated wine and ultreated wine,the content of caffeic aicd,syringic acid,(-)-epicatechin show positive correlations with wine color,while malvidin-3-O-glucoside and(+)-catechin show obviously negative correlations with wine color.In general,ultrasonic treatment improved the color quality of the wine,but did not change the correlations among the concentrations of these major phenolic compounds and the wine color.3.The effect of ultrasound treatment on the copigmentation for red wine has been studied.In order to illuminate the influence of ultrasound on the copigmentation in red wine,caffeic acid with its strong and stable copigmentation for wine color was selected as the co-pigment to add to the wine,and the caffeic acid-added wine was subjected to ultrasonic treatment.Results show that the copigmentation of caffeic acid was increased with storage time,and ultrasonic treatment can continuously enhance the copigmentation effect of caffeic acid.For the caffeic acid-added wine,ultrasound treatment can increase the absorbance of visible spectra,wine color,color intensity,browning index and proportion of polymeric anthocyanins,decrease the proportions of monomeric anthocyanins,and made the proportions of copigmented anthocyanins increase first and then decrease.Under ultrasound treatment,the monomeric anthocyanins gradually transforms into polymeric state with more colored and stable.In addition,when the wine added caffeic acid was treated by ultrasound,the evolution of malvidin-3-O-glucoside and caffeic acid in wine was accelerated,indicates ultrasound can continuously and steadily accelerate the copigmentation reaction between anthocyanin and caffeic acid to enhance the color of the wine.In summary,ultrasonic treatment can improve the color of red wine and have a persistent and irreversible effect on the the change of color characteristics and phenolic substances during storage.In addition,ultrasonic treatment can accelerate the copigmentation reaction of anthocyanin to improve the color of red wine.