Comparison Of Anthocyanin Stability During The Fermentation Of Blueberry Wine With Copigment And Mannoprotein

Color is an important indicator of wine quality evaluation,but pigments such as anthocyanins in raw materials are unstable during fermentation and storage,and are easily decomposed.Therefore,how to reduce the decomposition of pigments during the processing and storage of fruit wine and maintain the stability of color is an important issue in wine brewing.According to reports in the literature,the copigments are mostly phenols and flavonoids,which are non-covalent bonds with anthocyanins as stable complexes,and effectively avoid the degradation of anthocyanins;Mannoprotein is a zymosan that delays its degradation by binding to an anthocyanin moiety.Therefore,in this study,blueberry wine is taken as the research object,and two types of natural auxiliary color substances,ie,the copigment and the mannoprotein,are added to the pulp before fermentation.The difference in the auxiliary color effect was compared from the color difference,red shift phenomenon and auxiliary color,and the change of monomeric anthocyanin content in the wine body was further analyzed.On this basis,the best auxiliary color material was selected.In the first part,the auxiliary color effects of three complementary pigments(caffeic acid,syringic acid,and quercetin)on blueberry wine were studied.(1)The effect of the copigment on the acidity of the blueberry wine was not significant,and it had a certain influence on alcohol and residual sugar.Among them,caffeic acid was the most significant,indicating that it promoted fermentation;(2)The coloring of the blueberry wine was significantly enhanced by the co-pigment,the L* value decreased and the brightness decreased;the a* value increased and the red tone increased;the b* value decreased and the blue tone increased.Among them,the effect of auxiliary color of caffeic acid group is most significant;(3)The degree of binding of anthocyanins to the co-pigment was different and the content of anthocyanins increased.The caffeic acid group produced a red shift Δλmax of 3.43 at the end of the main fermentation and 3.63 at the end of the post fermentation;the M value of the auxiliary color at the end of the main fermentation was 53.16 and 59.01 at the end of the post fermentation,and the auxiliary color effect was most significant;(4)The copigment improves the anthocyanin content in the wine.The total anthocyanin content in the caffeic acid group was increased by 33.38% after the main fermentation,and increased by 53.05% after the end of the fermentation.The proportion of anthocyanin monomer content in the mallow was significantly increased by 3 to 5 percentage points;(5)As regards taste,the addition resulted in an increase in acidity,bitterness,astringency and salinity,and a decrease in sweetness,which was most pronounced in the caffeic acid group.The second part studied the additive color effect of different concentrations of mannoprotein(0.2g/L,0.25g/L and 0.3g/L)on blueberry wine.(1)Mannose protein will slightly increase the amount of residual sugar,reduce the acidity of blueberry wine and increase its alcoholicity,and the trend will increase with the increase of the concentration.It will also have the effect of promoting fermentation of wine;(2)Mannoproteins deepen the color of blueberry wine,that is,the L* value decreases and the brightness decreases;the a* value increases,the red tone increases;the b* value increases,the blue tone increases,and the color changed with the concentration increase;(3)The degree of binding of mannoproteins to anthocyanins is different,and the content of anthocyanins increases.The concentration of added mannoprotein 0.3g/L produced a redshift Δλmax of 4.63 at the end of the main fermentation and 5.33 at the end of the post fermentation;the M value of the auxiliary color at the end of the main fermentation was 62.88,and was 66.09 at the end of the post fermentation;(4)Mannoprotein increased the anthocyanin content of the wine.After the main fermentation was completed,the addition of 0.3 g/L mannose protein increased the total anthocyanin content by 39.42%,and increased by 57.46% after the completion of the post-fermentation.The proportion of anthocyanin monomer content in the mallow was significantly increased by 4 percentage points.The proportion of anthocyanin content in delphinium was also increased;(5)The mannoprotein had an optimal effect on the mouthfeel,in which the acidity,astringency,and bitterness were decreased,and the salinity and sweetness were increased.The degree of improvement was increased with increasing concentrations.Both types of additives can promote the fermentation of blueberry wine to a certain extent and deepen the color of the wine,and stabilize anthocyanins.Among them,the effect of caffeic acid in the copigment is the best,and 0.3 g/L of mannoprotein is the best.However,mannoprotein can optimize the taste,so the final determination of 0.3g/L mannoprotein is the best choice.