Studies On Purple Sweet Potato Vinegar And Its Beverages

In this paper, the process technology of purple sweet potato and its vinegar beverages were studied. The vinegar was made from purple sweet potato after the process of saccharification of potato residues, extracting of anthocyanin, alcohol fermentation, acetic acid fermentation, aging, clarifying. The research confirmed the optimization of incubation conditions of mixed culture alcohol fermentation and acetic acid fermentation was carried out. At the same time, changes of content of essential substance during vinegar processing were studied. Finally, the purple sweet potato vinegar was used as main raw material for vinegar beverages. The main results were as follows:The yeast and lactic bacteria mixed incubation in the alcohol fermentation. The results showed that the optimum time to inoculate lactic acid bacteria was the beginning of alcohol fermentation, and the optimal conditions were30℃of incubation temperature,0.3%of inoculation amount, the volume of the saccharification liquid was5:5and the fermentation period was84h. Under these conditions, the maximal observed alcohol degree up to7.15%, lactic acid reached up to0.62g/100g and the total acid reached up to0.66g/100g. Inoculating the lactic bacterial in the alcohol fermentation can significantly increase the final total acid content and the final lactic acid content.The acidic alcohol fermentation liquid was obtained from mixed culture alcohol fermentation. With the acidic alcohol fermentation as reagent, the optimum process parameters of ratio of solid to liquid1:10, time25.7min, temperature57.5℃and ultrasonic power300W were obtained for anthocyanins extraction from purple sweet potato power by Box-Behnken design of Response Surface, time of extraction1times. The maximum anthocyanins yield87.04mg/100gDW.With the extraction of anthocyanins as the crude fermenting liquor, the optimal fermentation conditions were inoculation amount10%, temperature30℃, broth content600mL, Under these conditions, the maximal observed the total acid reach up to6.27g/100g, the lactic acid reach up to0.412g/100g, anthocyanins yield were55.07mg/100mL. Changes of content of essential substance during germinated brown rice vinegar processing were studied. The content of reducing sugar, alcohol, free amino acid, lactic acid and anthocyanins showed decreasing tendencies; while aontent of total acid showed increasing tendency during acetic acid fermentation period. In aging process, total acid and lactic acid content did not change significantly in the purple sweet potato vinegar. Sold fermentation substrate of vinegar being isolated from oxygent, was effective to prevent the decomposition of acetic acid bacteria on lactic acid and acetic acid.The purple sweet potato vinegar was used as the main raw material for vinegar beverages, which mixed with the extracts of hawthorn, medlar, Chrysanthemum, liquorice, Kudzu, Puerariae Flos and Hovenia dulcis seeds and apple juice, to develop a kind of health soft beverage. The results showed that the basic ingredients of the purple sweet potato vinegar beverage were:20%purple sweet potato vinegar,45%the extracts of complex herbal,15%apple juice, and8%compound sweeteners. Fuzzy comprehensive evaluation methodology showed that the soft drink was acceptable to sensory test members.