Processing Technology Of Fermented Persimmon Wine With Low Methanol Production

In recent years,the consumer’s demands for fruit wines have been growing much more,while fermented persimmon wine,with low alcohol content but high nutrients,has shown a great market potential in future.However,methanol,a harmful chemical to people’s health,will be much produced during persimmon wine making because of rich pectin in persimmon fruit.At the same time,there are few reports about excessive methanol content in fermented persimmon wines.Therefore,based on the physicochemical properties of persimmon fruit of Niuxin,alcohol treatment for persimmon deastringency,selection of commercial pectinases and commercial yeasts,and optimization of fermented conditions were investigated,so as to achieve the effective processing technology of fermented persimmon wine with low methanol production.Under the conditions of the experiment,the main results obtained are as follows:(1)The results of alcohol treatment on persimmon quality(during after-ripening time)showed that,the use of 80% alcohol(v/v)treated on persimmon fruit for 6 days are the best for wine making,not only effectively making persimmon lose pucker,but also keeping persimmon high in sugar and acid content.It was also found that,there was some activity of pectin esterase in persimmon fruit and low methanol was produced during after-ripening period.(2)In the 17 fermented persimmon wines produced by different processes,the content of methanol ranged from 130 to 390 mg·L-1.Except high acid content in the wines,the other physicochemical indexes and the sensory quality of these wines are complied with the related national standards.Most of the fermented persimmon wines are clear and transparent,with yellow color,floral and fruity aroma,mellow and balanced body.These wines had high antioxidant activities,and there is significantly positive correlation between antioxidant activity and total phenols(P<0.01).(3)The results of selection of pectinases and yeasts suggested that,commercial pectinase D and Vitilecure KD were most suitable for making fermented persimmon wine with low methanol production.A reliable mathematical model was established,employing response surface methodology to optimize the fermentation conditions and produce wine with low methanol production.It showed that,the initial sugar content and initial pH value had significant effects on the methanol production(P < 0.01),while the fermentation temperature and the amount of yeast added did not significantly(P > 0.05).The optimal fermentation conditions were determined:fermentation temperature 17 ℃,initial pH value 3.70,initial sugar content 235 mg·kg-1,and yeast addition amount 180 mg · kg-1.Under the conditions,the methanol content in fermented persimmon wine was 149 mg·L-1.