Changs Of Physical And Chemical Compositions And Tannin In The Fermentation Process Of Persimmon Wine

Persimmon fruit is seasonal fruit and has poor shelf-life. Persimmon wine is rich of nutrients. Use persimmon fruit to produce wine could develop persimmon industry in rural areas of China. Tannin is an important flavor compound in wine and affects the composition of the aroma compounds in the aging process. However, due to its complex composition and structure, tannins easy to occuring reastringenting phenomenon in storage and affecting persimmon wine’s flavor and storage stability. So it is necessary to study variation of tannin and other physicochemical index change rules during the fermentation, this research could improving persimmon wine’s flavor, controlling aroma, increasing biological stability, and developing persimmon industry.This research use Diospyros kaki L., from HuiXian County Henan Province as the experiment materials, determine the optimum fermenting index and tannin extracting method. Then determine the tannins content and components change in the fermentation process by Folin-Cioealteu method and LC-MS-MS. The results show:1. In this paper, the traditional production technology of persimmon wine is improved, The optimum fermentation condition would be original sugar concentration of230g·L-1, pH value of4.0, yeast addition of0.5g·L-1, and SO2addition of150mg·L-1The fermentation technology of persimmon wine is researched.The sugar content, acidity, protein and aroma compositions of persimmon were studied in the fermentation process. Generally, total sugar content decreases, dropping rate and degree are different according to the original fermentation conditions. Total acid content presents a rising trend in the first six days and then remains in a stable level. The protein content decrease slightly, but no significant difference among the treatments. The aroma of persimmon fruit is weak, main components are alkanes and esters, such as tetradecane,2-methyl-decane, hexadecane and ethyl decanoate. The hydrocarbons content are decreased during the fermentation. Esters content and varieties increase gradually from one kind to11kinds as well as alcohols and aldehyde appeared. Ultimately, the main aroma components are alcohols and esters, such as1-pentanol, phenylethyl alcohol, ethyl decanoate, ethyl octylate, ethyl laurate.2. Tannin extracting technology is studied. On the base of single-factor affection experiments, such as temperature, extraction time and solvent, etc, the best extraction technology of total tannins is optimized by the orthogonal experiment. The optimum extracting conditions are temperature80℃, solid-liquid ratio (V∶W)20∶1, ethanol concentration80%, extract time1h. Tannin components of persimmon determined by HPLC-MS-MS were Gallic acid, Catechin, Epicatechin and Epicatechin gallate.3. The changes of total tannin content and tannin components in the fermentation are studied. During fermentation, total tannin content first increases, and then decreases until the end of fermentation. Tannins components are analyzed by LC-MS-MS. It is confirmed that Gallic acid、Epicatechin gallate、 Catechin、 Epicatechin and Epigallocatechin existed in persimmon fruit and wine. During the fermentation process, Gallic acid content first increases slowly to the maximum at the eighth day and falls thereafter, until the end of fermentation. In the first six days epicatechin gallate content increases rapidly, then decreases later, until the end of fermentation. In the fermentation process, Catechin content changes among6-8μg/mL with no significant difference. Epicatechin content increases to the maximum in the first sixth days and goes down thereafter. On the sixth day, Epigallocatechin was emerged and increases rapidly in the later fermentation.