| Dimethyl dicarbonate(DMDC) is a kind of fruit juice beverage preservatives in Chinese standards of hygienic standards for food additives. Researchers prove that DMDC is a kind of potential non-thermal sterilization agent with the quick general effect of sterilization under indoor temperature or low temperature, and quickly breaks down to traces of methanol and carbon dioxide in water, which don’t affect human body health and quality of products. At present, the application of DMDC is in the promotion stage domestic and overseas, mainly used in the sterilization of fruit & vegdtable preservation and fruit juice beverage. In brewing technology, the application of DMDC in the wine is carried out and researched more deeply,but in other wine category has not been reported. So this topic explored the effects of DMDC fermentation pre-treatment on the fermentation characteristics and quality of fruit wine originated from two prolific representative fruits of Guangdong(litchi and chachiensis),relative to the non-sterilization, thermal sterilization and sulfite sterilization. Main conclusions are as follows:1. Different pre-treatments such as DMDC, sulphites and pasteurization were investigated for their effects on the fermentation characteristics of litchi wine, by measuring the microbial variation of the before and after of litchi juice sterilization, changes of titratable acid, alcohol, fusel, color, polyphenols during the main fermentation of six days and volatile components at the end of fermentation. The results showed that compared with the control group, groups added DMDC or sulfites as well as processed with pasteurization could well inhibit the growth of the natural bacteria in litchi juice, delay the decline of p H and the increase of titratable acid, and improve the alcohol yield of litchi fermentation wine.Especially important, compared to sulfites, DMDC was the more important contributor for the sterilization of yeasts, lactobacillus and moulds in litchi juice(p<0.05). However, the polyphenols retention rate of the experimental group added sulfites was significantly higher than the others(p<0.05), and sulfites could work on the effectiveness of color-protection with the minimal change of △E*; The unique flavor ingredient in litchi wine was lost greatly bythe pasteurization. In conclusion, DMDC can replace or partially replace sulfites or the pasteurization in the application of litchi wine.2. Three treatments in the experiments were arranged: fresh chachiensis juice was treated respectively in three different ways: DMDC sterilization, pasteurization, and non-sterilization(the control). Then, we monitored and compared the dynamic indicators(total soluble solid,sugar compositions, alcohol, fusel, p H, total acid, organic acid, ascorbic acid, and antioxidantactivity, etc) of chachiensis fruit wine during fermentation and the microbial variations at the cross-fermentation among the three treatments. The fermentation experiment results showed that, compared with the control(non-sterilization treatment), the treatments with DMDC addition or pasteurization could improve the effective utilization of sugar and the yield of ethanol and restrain the synthesis of fusel by killing unwanted bacteria. The contents of ethanol in the control, DMDC treatment, and pasteurization treatment were respectively13.10%, 13.30%, and 13.73%. Importantly, compared with the pasteurization treatment,DMDC treatment allowed the higher ascorbic acid concentration(211.40~221.70 mg/L) and antioxidant activity(20.83~23.26 μmol TE/m L) in chachiensis fermentation liquor. However,DMDC treatment showed the higher residues of resistant bacteria such as lactobacillus and the increment of ascorbic acid. To sum up, DMDC sterilization is worthy of further application investigation as a non-thermal sterilization technology in the fermentation pre-treatment of chachiensis fruit wine. |
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