Study On Improving The Quality Of Wheat Qu For Shaoxing Rice Wine

Wheat Qu for Shaoxing rice wine was studied in this paper. According to the results ofprevious studies in our lab, the microorganisms which affect the quality of wheat Qu wereobtained from wheat Qu by culture-dependent method and used for making cooked wheat Quby multi-strain fermentation. The optimized fermentation conditions were established bymathematic statistics and computer simulation. And furthermore, the effects of the fortifiedQu on the quality of rice wine were studied. The main results were as follows.Microorganisms and proteins in wheat Qu are the main factors that affect its quality. Themicrooganisms that come from wheat Qu and the environment of rice wine factory wereidentified. Our results showed that the main enzyme produced microorganisms were Rhizopussp、Aspergillus sp. and Bacillus sp. Among them, the strains of Aspergillus sp. had strongabilities of producing glucoamylase and protease. Otherwise the strains of Bacillus sp. hadstrong abilities of producing α-amylase. By comparison, Aspergillus oryzae ZW12andBacillus amyloliquefaciens were finally selected for our study to make cooked wheat Qu.The fermentation conditions of wheat Qu-making by fungi were performed andoptimized by single factor experiments and response surface analysis experiments. Theoptimal conditions were as follows, incubation time was47.21h, the ratio of material to waterwas1:0.81, Aspergillus oryzae strains Su-16and ZW12were mixed at a ratio of1:2. The totalinoculum was5.5%, fermentation temperature was30℃. The enzymes activity ofglucoamylase, α-amylase and acidic protease were3.5%,77.3%,59.7%higher than thecontrol of traditional cooked wheat Qu, respectively.Furthermore, Uniform Design was used to optimize the conditions of fermentation byfungi and bacteria to make the cooked wheat Qu. The optimized conditions were that after36h fermenting with the fungi only, bacteria was added to the fermentation, inoculum was3.5%.Fermentation temperature was up to36℃and consistent ferment in48h. The enzymesactivity of glucoamylase, α-amylase and acidic protease were38.6%，106%,100%higherthan the control of traditional cooked wheat Qu, respectively.The quality of cooked wheat Qu made by multi-strain was measured. The enzymesactivity of glucoamylase, α-amylase and acidic protease were1425.9U/g、15.5U/g and427.8U/g, respectively. The contents of peptide, free amino acid were8.1%and734.02mg/100g.There were more aroma precursors. The fermentation rate was speeded with the improvedcooked wheat Qu and fermentation time was shortened. The alcoholicity were17.4%higherthan control sample and the utilization of raw material was improved.