A Study On Submerged Fermentation Of Litchi Vinegar

Litchi (Litchi chinensis Sonn.) is originated from China. It is juicy, sweety and rich in nutrition. It also has many health care efficacy, such as atntioxidative effect, anti-aging, blood lipid regulation and so on. A research on Litchi vinegar with Litchi as its raw material has been done in this paper, which using liquid state fermentation and segregating microorganisms by microfiltration. The main methods and results obtained are as follows:(1)The alcoholic fermentation comparison experiment of angel yeast, CICC1312 and AS2.300 indicated that the angel yeast and CICC1312 can be used in mixed fermentation. The contents of total esters in Litchi vinegar was the highest when the two yeast mixed at a proportion of 2:1. The amino nitrogen could increase to 108.6mg/100mL after polypeptide was added at 4g/L.(2)The alcoholic fermentation was optimized by means of quadratic general rotary unitize design in the research of revealing alcoholic fermentation rules. The regression equation of the four factors to alcohol content (Y) was: Y=7.40000+1.28750X₂-0.07917X₃+0.11250X₄-0.03021X₁²-0.06771X₂²-0.10521X₃² -0.05521X₄².According to the regression equation, the optimum alcoholic fermentation condition was obtained, the inoculation volume was 0.15%, reducing sugar content was 18g/100g, temperature was 30℃, pH value was 4.5 and the alcohol content got to 9.76%. A quadratic function between alcohol and sugar content was obtained: Y= -0.06771X₂²+1. 28750X₂+7.45729.Based on the eqution, the sugar content could be calculated in alcohol fermentation from the alcohol content required during acetic acid fermentation.(3)The AS1.41 acetobacter was the optimum by screening acetobacter from AS1.41 and shanghai brewing 1.01. The appropriate range of inoculation volume, alcohol content and temperature was find out through single factor experiments in research of acetic acid fermentation. Then an orthogonal test with three factors and three levels had been done and the optimum acetic acid fermentation condition was obtained, the temperature was 33℃, alcohol content was 6% and inoculation volume was 10%, the acidity got to 5.91 g/100mL.(4)The research on which clarified by silica gel and segregated microorganisms by microfiltration with ceramic membrane indicated that the method could remove microorganisms in Litchi vinegar efficiently and transparency reached to 96.3%. It also had little influence to the flavor and the main content be preserved well.