Optimization Of Saccharification And Fermentation For Barley Malt-Purple Sweet Potato Wine And Analysis Of Its Quality

Purple sweet potato (Ipomoea batatas (L.) Lam) which contains variety of nutrients is widely cultivated in the northsouth of china. Due to the fact that Purple sweet potato possess antioxide compounds, such as canthocyanins and phenolic compounds, purple sweet potato has become one of the most promising crops. In our study, barley malt and purple sweet potato were used as raw material, and barley malt was also used as an agent with glycosylating capability. Response surface methodology was used to optimize saccharification and fermentation condition optimization of barley malt-purple sweet potato wine. On this basis, we made barley malt-purple sweet potato wine, and compared the quality of barley malt-purple sweet potato wine with traditional purple sweet potato wine.The main results are as follows:1. Determination of optimum conditions for saccharification techniqueFrom the single factor and response surface test, we concluded that the effect of various factors in test on the content of reducing sugar was very significant, and the primary and secondary order of influence showed that:pH>saccharification time>sacchari-fication temperature. The optimal conditions were as follows:the barley malt impregnated material liquid ratio 1:2, barley malt amount 55%, saccharification temperature 65 ?, saccharification time 4.8 h, pH=5.6, and the content of reducing sugar reached to 16.21%, and it also resolved the problem that the alcohol content of barley malt-purple sweet potato wine was too low caused by the low content of reducing sugar.2. Determination optimum conditions for fermentation techniqueFrom the single factor and response surface test, we concluded that the effect of various factors in test on the alcohol content of barley malt-purple sweet potato wine was very significant, and the primary and secondary order of influence showed that: fermentation temperature>yeast addition quantity>pH. The optimal conditions were as follows:fermentation temperature 26 ?, yeast addition quantity 0.08%, pH=3.4, and the alcohol content reached to 12.42%vol. It provides a certain reference for the industrial production of barley malt-purple sweet potato wine.3. The quality analysis of barley malt-purple sweet potato wine(1) Analysis results of sensory:The appearance and taste of two kinds of purple sweet potato wine are good, and in accordance with the quality standards of purple sweet potato wine. No significant difference in sensory evaluation.(p>0.05)(2) Analysis results of the main physical and chemical index:The dry extract content of barley malt-purple sweet potato wine is 166% higher than that of traditional purple sweet potato wine, and the anthocyanin content of barley malt-purple sweet potato wine is 62% lower than that of traditional purple sweet potato wine. In general, the alcohol content and acidity of two kind of purple sweet potato wine is appropriate, and the main physical and chemical indexboth meet the standards of purple sweet potato wine thus it is suitable for drinking.(3) Analysis results of aroma components:26 aroma components were detected in barley malt-purple sweet potato wine. Among them,38% alcohols,48.05% esters,12.26% acids,0.22% ketones,1.01% phenols,0.46% alkanes and olefins.23 aroma components were detected in traditional purple sweet potato wine. Among them,25.39% alcohols, 64.04% esters,9.1% acids,0.25% ketones,0.92% phenols,0.31% alkanes and olefins. The main aroma substances in barley malt-purple sweet potato wine and traditional purple sweet potato wine are both alcohols and esters. The main alcohols in barley malt-purple sweet potato wine are phenethyl alcoh, and the main esters are ethyl decanoate, phenyl ethyl acetate, octylic acid ethyl ester and isoamyl acetate. The main alcohols in traditional purple sweet potato wine are also phenethyl alcohols, and the main esters are ethyl decanoate, ethyl laurate, phenyl ethyl acetate and octylic acid ethyl ester.