Optimization of Cultural Conditions for Vinegar of Litchi ( Litchi chinensis Sonn.) in Liquid State Fermentation

In order to enhance the value of industry application of litchi, fermentation experiment of litchi vinegar was conducted to optimize process parameters. The technology of alcohol fermentation was carried out to investigate the effects of parameters such as original sugar content, yeast inoculation amount, pH value and fermentation temperature. A Box-Behnken experimental design of 3-factor and 3-level was used to build the secondary multivariate regression model related to the yield of acid including inoculation amount, original alcohol content and fermentation temperature, and explore the effect of process parameters of acetic acid fermentation above on the yield of acid in the light of response surface plots. Finally the fermentation process of its acetic acid fermentation was optimized using Box-Behnken methodology. Results were as follows. The optimal process of its alcohol fermentation was as follows: original sugar content, 16%; yeast inoculation amount, 5%; pH value, 3.5 and fermentation temperature, 30~32 °C. The optimal process of its acetic acid fermentation optimized by response surface methodology was as follows: inoculation amount, 10%; original alcohol content, 7.0% and fermentation temperature, 30 °C, in the optimal condition the yield of acetic acid was 52.45 g/L. The secondary multivariate regression model showed as follows. The effects of inoculation amount and original alcohol content were non-significant, and that of fermentation temperature extremely significant. The interaction of inoculation amount and original alcohol content was extremely significant. In conclusion, the regression model was accurate and reliable; the optimal fermentation technology of litchi vinegar was advisable.