Blueberry Wine Fermentation And Its Effect On Phenolic Compounds

Blueberry is an Ericaceae Vaccinium.L genus Plant, and the fruit of the plant has high nutritional value. In particular, the polyphenol compounds (e.g. anthocyanins and phenolic acids) contained in the fruit could show a variety of biologically activities such as antioxidant, anti-mutagenic antibacterial, and so on. Blueberry wine was paid more attention by consumtions because of its high nutritional value, but wether the fermentation process of the blueberry wine affect the structure and function of the phenolic compounds in blueberries or not is worth studying, and this is also the focus of this dissertation.In this dissertation, firstly, the higher nutritional value of blueberry variety which was more suitable for the fermentation of blueberry wine was screened out by analyzing and assessing the nutritional value and polyphenol components of different blueberry varieties. And then, the response surface method was used to optimize the blueberry wine fermentation parameters. Under the optimal fermentation conditions, Blueberry wine was made and then aging. Finally, the changes of antibacterial activity and reducing power that were before fermentation and after aging were investigated. Meanwhile, the polyphenols groups were identified with LC-MS. The reasons that leading to phenols function changes were analyzed. The main results and findings were summarized as follows:1In this paper, Tifblue, Premier, Brightwell, Garden blue and Powder Blue were used as the research materials. Nutritional value and polyphenols components differences of the five blueberry varieties were investigated. The results showed that the sugar content in garden blue was11.59mg/100g,121.23%～132.31%higher than that of the other four varieties, soluble protein content was1.68～4.29times than that of the other four species, free amino acid content was3.28%lower than Premier, However,68.66%～108.06%higher than the other three varieties. It revealed that the sugar content of garden blue was suitable for the fermentation of wine.Polyphenols compounds, anthocyanin content and composition, in the process of fermentation, especially after fermentation of five varieties of blueberry wine were analyzed. Results showed that phenolic compounds and anthocyanin composition of the different blueberry varieties were similar, but their contents differ significantly. Anthocyanin content and total phenol index showed a significant positive correlation, the correlation coefficient was0.994. Before fermentation, Anthocyanin content of Garden blue was1.43to3.76times of the other four varieties of blueberries, and its phenols content was1.32to2.36times of the other four varieties. In the process of alcohol fermentation, the total phenol index was significantly increased, while the anthocyanin content decreased significantly, the anthocyanin content of Garden blue declined at least, and the content of polyphenols compounds increased more than the other four varieties. After fermentation, the total phenol index of Garden blue was34.97,2.25to5.25times in the other four varieties, the anthocyanin content was113.49mg/L,124.67%and425.40%higher than other varieties.2Wines made without or with skin contact fermentation (Q&D), with Skin-contact fermentation after heat treatment (R) were used research processes. Effect of the above different processes on alcohol and anthocyanins of blueberry wine were investigated. Results showed that three fermentation didn’t significantly affect the wine alcohol (p>0.05), but the impact on anthocyanins and total phenol index was larger. Before fermentation, anthocyanin content of blueberry mash and total phenol index are209.24mg/L and30.95respectively in the fermentation process of hot dipping, the anthocyanin content was2.01times and1.26times of the other two processes, and the total phenol index of76.35%and41.65%higher than the other two processes. Compared with before fermentation, blueberry wine anthocyanin content decreased by34.87%,15.59%and34.34%, and total phenol index rose0.2,11.6and-1.45in the three fermentation process. In addition, the loss of anthocyanins and polyphenols of blueberry wine fermentation conditions with slag at least after the end of the fermentation, both of them have maximum144.47mg/L and33.45.The content of polyphenols and anthocyanins were higher under D conditions. With D conditions, the alcohol and content of anthocyanin as optimization targets, and Box-Behnken experimental design was used to optimize wine fermentation parameters. Results showed thatinitial pH value was3.7, brix was24°Brix, the amount of (NH3)2HPO3was162mg/L and fermentation temperature was28℃. Under these conditions, the content of anthocyanins and alcohol in the blueberry wine reached190.3±2.65mg/L and (11.26±1.56)°fter fermentation of14days, respectively.3In the process of fermentation and aging, changes of the polyphenols compounds, anthocyanin contents, its components and color in the wine were studied. Anthocyanins that were the major coloring substances in the wine of blueberry derivative relative stable macromolecular compounds, and the color of wine deepened and became to stability. Antibacterial and antioxidant activity of wine phenolic extract showed a decreased tendency. The dissolution of phenolic acids in the marc leaded to the rise of the phenolic acid content and the decreased of anthocyanins during wine fermentation. The components2and3which changed significantly during fermentation were analysised with MS. The components2and3were protocatechuic acid andchlorogenic acid, respectively.4Antimicrobial activity and reducing power of polyphenols compounds of different blueberry wine brewing stage were also studied in this work. Results showed that, with the extension of the fermentation time, the minimum inhibitory concentration of blueberry polyphenols negative bacteria E. coli-positive bacteria Bacillus respectively increased to20mg/L and40mg/L from10mg/L and5mg/L, that means that the antibacterial activity of phenolic compounds in blueberry extract decreased as the fermentation process. In addition, reducing power was enhanced with the increased concentration of blueberry polyphenols. At the same concentration of the phenolic extract, reducing power of the phenolic compounds decreased by12.77%after fermentation, and decreased by6.77%in the process of aging. Therefore, wine phenolic extract antibacterial and antioxidant activity of bacteria show a downward trend with the extension of the fermentation time.