Optimal Process And Quality Control Of Persimmon Wine

This research, with the DiospyroskakiL．from HuiXian County, Henan Province as the experiment materials, is designed to study the index changes of sugar, soluble tannin and total acid in the maturing process of persimmon, the determination of the optimum processing conditions for persimmon wine producing, and the determination of the persimmon stability. The results show that: During the maturing of persimmon, the contents of its main components present regular changes with the fruit growing: The soluble content and sugar content go up gradually and remain stable when their peak values reached; The tannin content decreases mildly and so does the content of protein; The low total acid content shows no great change but with certain degree of differences among different fruits. The fruits matured enough with orange color and hardness greater than 20×105Pa should be selected so as to guarantee the sugar contents and low tannin contents, and also the stability and intactness in the transportation. The collected persimmon can be kept under normal temperature for 10～15d for natural deastringency, and decreases of hardness to 7～8×105Pa and tannin content to 0.18% respectively, which can start the ferment smoothly and mild the bitter and astringent taste of the wine. During the brewing process, the acidity should be raised with adding sufficient SO2. The inoculation quantity of the yeast can be raised properly for the starting of the ferment. Over addition of yeast would make the ferment too fast which will add the difficulty of temperature control and the clarification of the wine, and the loss of aroma as well. The tannin content will be lowered during the ferment process with the decrease of the sugar content. If the time before the ferment properly be longered, the content of soluble tannin of the wine can be lowered. The optimum processing condition would be ferment temperature of 18.5℃,sugar content of 200 g·L-1, pH value of 4.0, and yeast addition of 0.3 g·L-1.The microbe in persimmon wine appears in a comparatively good stable state but the protein disease and polyphenol do not. In order to obtain a better clarification, the wine can be treated with gelatin(0.25g·L-1)and tannin (0.125 g·L-1) to improve its stability; while if the tannin content is too high, the wine can be treated by adding 0.35 g·L-1PVPP. About 1 g·L-1 of malic acid is contained in the wine, which may lead to malic acid and malolactic fermentation. Because of the low acidity in the persimmon wine, the fermentation should be restrained, and the sufficient amount of SO2 should be added in all the stages of the fermentation process in order to keep the free SO2 above 50 mg·L-1 for the biological stability of the wine. Persimmon liqueur can be produced to better its taste and the optimum direction for semi-dry persimmon wine is 12 g·L-1 of sugar, 0.3% of citric acid and 15o of alcohol contents. The bitterness and sourness of semi-sweet are light compared with that of dry wine, because its sugar content is raised which covers up the bitterness of the tannin. The optimum direction of it is 30 g·L-1 of sugar, 0.2% of citric acid and 20o of alcohol contents.