Key Process Optimization Of Black Glutinous Rice Wine And Stability Study Of Its Anthocyanin Fraction Fraction

The fermentation process of black glutinous rice was optimized by using black glutinous rice as raw material,thus solving the problem of low raw material utilization during the fermentation of black glutinous rice.The fermentation process of black glutinous rice wine was optimized by adding acid protease auxiliary wine malt to black glutinous rice wine,and the dynamic changes of volatile aromatic substances during the fermentation process were monitored by electronic nose and GC-IMS.To address the problems of cloudiness,unstable structure and colour presentation of black glutinous rice wine,the wine was treated with different clarifying agents,the best clarifying agent was selected,and the clarification degree of black glutinous rice wine was used as a reference indicator to optimise the clarification conditions by ultrasound with the aid of ultrasound.The effect of the co-colouration and the influence on the colour and stability of the colour glycosides were investigated.The main findings are as follows:（1）The optimal fermentation process parameters for black glutinous rice wine were obtained:acid protease and sweet wine bran were added at 0.15%and 0.5%,the fermentation time was 4 d and the fermentation temperature was 30°C.Under these conditions,the fermented black glutinous rice wine was bright and purplish red in colour and had a strong rice aroma with a harmonious aroma,and the sensory score was improved by 21.2%,while the total sugar content was controlled at 89.2 g/L,shortening the The fermentation time was shortened,the wine production efficiency increased and the alcoholic strength improved by35.7%.The physical and chemical indicators of total acid and amino acid nitrogen also increased,and the addition of acid protease had less effect on the total phenolic content of the black glutinous rice wine.（2）Electronic nose and GC-IMS were used to monitor the changes of volatile flavour substances in black glutinous rice wine during 6 d of fermentation.From the results of the electronic nose,the aroma response values of the experimental group were consistently higher than those of the control group,which indicated that the addition of acid protease could promote the aroma formation of black glutinous rice wine;the qualitative results of GC-IMS yielded 42 volatile odour components,of which the main aroma-presenting substances were esters and alcohols 22 species,and 20 species of other acids,aldehydes and phenols,etc.At the same time,the experimental group had more aroma constituent substances and higher concentrations than the control group,producing more esters,alcohols and aldehydes,which gave the black glutinous rice wine its strong fruit and wine aromas（3）Process parameters were obtained to optimize the clarification of black glutinous rice wine by ultrasound-assisted acid protease:the optimum addition of acid protease was determined to be 0.7%,and the clarification of black glutinous rice wine reached88.76%±1.26%after 27 min of ultrasound at 36°C and 180 w.The model established in this experiment was reliable and valid,and the regression was significant.The clarification of black glutinous rice wine was used as an evaluation index to investigate the effect of sonication and enzyme treatment on the clarification effect of black glutinous rice wine.After treatment,the physicochemical indexes of black glutinous rice wine did not change much,the alcohol,total sugar and total phenol content decreased,the amino acid nitrogen and total acid content increased,the clarification increased by 26.8%and the sensory score increased by 15.7%.（4）As the concentrations of Al³⁺,caffeic acid and ferulic acid increased,all the black glutinous rice wine containing C3G had a significant color enhancement effect and red shift phenomenon,and all three auxiliary color factor treatments significantly improved the color parameters of black glutinous rice wine,and the auxiliary color effect at the same concentration:Al³⁺>caffeic acid>ferulic acid.（5）When different concentrations of caffeic acid and ferulic acid were added to the black glutinous rice liquor containing C3G/Al³⁺,both caffeic acid and ferulic acid could affect the auxochromatic effect of Al³⁺on C3G compared with the liquor with only C3G/Al³⁺added,and the appropriate ratio could enhance the auxochromatic effect of C3G and enhance the color of the liquor itself;too high a concentration would lead to an antiauxochromatic effect on the liquor.（6）It was observed that the addition of Al³⁺,caffeic acid and ferulic acid improved the acid-thermal stability,light stability,storage stability and antioxidant properties of anthocyanin in black glutinous rice wine liquor,and that the addition of caffeic acid and ferulic acid to black glutinous rice wine liquor containing C3G/Al³⁺respectively could better protect anthocyanin degradation and reduce anthocyanin loss in black glutinous rice wine than the addition of these three co-colouring factors alone,while also contributing to wine colour stability during storage.