Biotransformation Of Anthocyanins During Fermentation Of Mulberry Wine

Anthocyanin is an important kind of biological activity substance andcharacteristic constituent in mulberry. That is a significant representation for thequality of mulberry processing product. It had been detected that the anthocyanin ofmulberry juice was changed remarkably by means of brewing and the content wasreduced significantly. This thesis mainly studied the anthocyanin dynamic variation,design a series of experiments to explore the factor of anthocyanin biotransformation,in order to provide basis and approaches for reducing the loss of anthocyanin inproduction. The main contents and results as follows:1. The mixture of concentrated mulberry juice and colourless grape juice wasused in initial fermentation medium of fruit wine to simulate mulberry wine fermentationprocess. The dynamic variation of total anthocyanin and monomer anthocyanin contentwere observed. The change of sugar content, alcohol content and pH value wereanlysised. the results showed that total anthocyanin and monomer anthocyanin contentwere mainly altered during the first7days and the total anthocyanin was droppedfrom39.1mg/L to20.5mg/L; Two main anthocyanins were detected different trend.The Cyanidin-3-glucoside content was reduced from18.6mg/L to1.0mg/L. and therate is94%, while the cyanidin-3-rutinoside content was reduced from20.5mg/L to17.0mg/L. and the rate is17%. Sugar conent was decreased from25%to10%andalcohol content was increased from0%vol to12%vol. The pH value of mulberry winewas changed regularly, up first then down, during the sugar conent was decreasedrapidly to produce alcohol. The peak value was4.71. The pH value was returned backto initial one after the yeast did not consume the sugars. It indicated that thebiotransformation of anthocyanin was not only closely related to biochemical changessuch as the glycometabolism of yeast and the alcohol production, but also thechemical structures of anthocyanins themselves.2. To study the impact factor on anthocyanin biotransformation in fermentationof mulberry wine. Some parameters including carbon source、 nitrogen source、alcohol、inorganic ion、 initial pH and initial yeast inoculum size was used in differentmeduims to explore their impacts on anthocyanin in fermentation. Results showedthat more anthocyanins were degraded with bigger sucrose concentration increasedwithin25%sucrose concentration. In particular rang of concentrations, the degradation ofanthocyanin was positively correlated with nitrogen source concentration, and theethanol procuction was decreased while adding nitrogen source simultaneously. Theethanol content was not influenced remarkably by the addition of inorganic salts, andanthocyanin was the most degraded after adding ferric sulfate(the rate was86.3%),while the stability of anthocyanin in fermentation broth was improved by the addtionof zinc sulfate （the rate was78.6%）. The anthocyanin was profitably reserved in lowinitial pH value, and the Peak degradation rate was obtained in4.5pH value. In addition, the cyanidin-3-rutinoside content was little influenced by each parameters inthe fermentation. In conclusion, the degradation of anthocyanin could be increased bythe addition of carbon and nitrogen source due to the beneficial to the metabolism ofyeast. High pH value and ferric ion addition made anthocyanin was easier degradeddue to reducing the stability of anthocyanin themselves.