A Study On The Quality Indicators And Anthocyanin Components Of Two Kinds Of Purple Sweet Potato Wine

The flesh of purple sweet potato is purple because it contains a large amount of anthocyanin. Up until now, most studies on the purple sweet potato wine focus on the fermentation process, while qualitative analyses on the anthocyanin of varieties of purple sweet potato wine have rarely done. Thus, this dissertation studies the physicochemical indexes and color changes of a variety of purple sweet potato wine which are made of different raw material. Besides, the present paper evaluates the organoleptic and hygienic indexes of these kinds of finished purple sweet potato wine. The results are as follow:1. The analysis of the anthocyanin content and color change of the two kinds of purple sweet potato wine:the Vietnam purple sweet potato wine:L*=47.6, a*=65.71, b*=6.91, C*=66.224, H=0.104while the anthocyanin content is67.34μg/mL. The Japanese purple sweet potato king wine:L*=53.12, a*=58.86, b*=7.51, C*=69.348, H=0.227and the anthocyanin content of the Japanese purple sweet potato king wine is79.62μg/mL. Through the color analysis, two kinds of color purple sweet potato wine is reddish.2. The comparison of anthocyanin components in the two kinds of purple sweet potato wine:with the UPLC-ESI-MS method, the anthocyanin components of the two kinds of purple sweet potato wine are analyzed. The experiment identifies19kinds anthocyanin in the Vietnam purple sweet potato wine, respectively, cyanidin-3-glucoside,peonidin-3-sophoroside-5-glucoside,cyanidin-3-hydroxylbenzoyl-sophoro side-5-glucoside, cyanidin-3-feruloyl rutin-5-glucoside and so forth. However, in the the Japanese purple sweet potato king wine, the experiment identify Cyanidin-3-coffee acyl p-coumaric acyl sophoroside-5-glucoside, cyanidin-3-double p-coumaric acyl sophoroside-5-glucoside, cyanidin-3-double feruloyl sophoroside-5-glucoside, and peonidin-3-double feruloyl sophoroside-5-glucoside. This shows that wine samples made of different purple sweet potato cultivar lead to the difference of anthocyanin components.3. Sensory evaluation and microbiological index identification of purple sweet potato wine:(1)Physical and chemical analysis:the Vietnam purple sweet potato wine sample: the alcoholic strength is13.5%vol, the total acid content is3.6g/L, the reducing sugar content is3.2g/L, the free sulfur dioxide content is7.28mg/L, the sulfur dioxide content is45.96mg/L, the volatile acid content is0.45g/L, the dry extract is23.8g/L, pH4.0,the iron content is2.2762μg/mL,the copper content is0.1024μg/mL; the Japanese purple sweet potato king wine sample:the alcoholic strength is13.5%vol, the total acid content is4.1g/L, the reducing sugar content is3.55g/L, the free sulfur dioxide content is7.39mg/L, the sulfur dioxide content is46.32mg/L, the volatile acid content is0.52g/L, the dry extract is26.7g/L, pH3.9,the iron content is0.9442μg/mL,the copper content is0.0407μg/mL.(2) Sensory evaluation:the Japanese purple sweet potato king wine is deep purplish red, clear and transparent, glossy, rich in flavor, with the special fragrance of purple sweet potato, and sour smell. It is comfortable to drink, refreshing, slightly fruity and with long aftertaste. In comparison, Vietnam purple sweet potato wine is rosy red, clear and transparent, glossy, rich in flavor, with the special fragrance of purple sweet potato, slightly sour. And it is also comfortable and refreshing to drink, with long aftertaste and unique flavor.(3) Analysis of microbial indicators:The total number of bacteria (CFU/mL)^50, coliforms (MPN/100mL)<3, pathogenic bacteria (Salmonella, Shigella, Staphylococcus aureus) have not been identified.(4) Hazardous analysis:The methanol content of the wine was51.14mg/L by GC. The comprehensive index shows that purple sweet potato wine is of good quality and suitable for drinking.