| Konjac fly powder is a kind of by-product in konjac flour processing, which is rich in resources and contains a lot of starch. The brewing of konjac fly powder whiskey has some advantages, which is not only reflected in turning waste into wealth and decreasing environmental pollution, but also in enhancing the types of konjac food as well as promoting the development of the alcoholic beverage industry with much economic and social benefit.In this thesis, we studied the fermentation characteristics of konjac fly powder and investigated the optimum conditions of acid hydrolysis, enzymatic hydrolysis, alcoholic fermentation of konjac fly powder and solid state fermentation for enzyme production of Aspergillus niger. And furthermore, we also studied the optimum condition of konjac fly powder whiskey oak barrels. Detailed studies are as follows:(1) For acid hydrolysis of konjac fly powder, four main factors that affect the hydrolysis effect were investigated:concentration of hydrochloric acid, liquid-solid ratio, acid hydrolyzing temperature and acid hydrolyzing time. Moreover, using the yield of reducing sugars as an index, we optimized the optimum conditions of hydrochloric acid hydrolyzing konjac fly powder by Lg(34) orthogonal test:acid hydrolyzing temperature was90℃, acid hydrolyzing time was100min, hydrochloric acid concentration was4mol/L, liquid-solid ratio was15. Under these conditions, the yield of reducing sugars of konjac fly powder by acid hydrolysis was39.48%. Heavy-secondary degree of the factors range in order as left-to-right:acid hydrolyzing temperature> hydrochloric acid concentration> acid hydrolyzing time> liquid-solid ratio.(2) For the composition of enzyme-prducing medium of Aspergillus niger solid state fermentation, we adopted L9(34) orthogonal test to investigate the factors:wheat bran-rice ratio, the water-solid ratio, content of dipotassium hydrogen phosphate, the content of ammonium sulfate using enzymatic activity of glucoamylase as index and optimized the optimum match as A3B1C1D3, namely wheat bran-rice ratio at3, water-solid ratio at100%, ammonium sulfate content of1%, dipotassium hydrogen phosphate content of0.4%. Under these conditions, the enzymatic activity of the glucoamylase Aspergillus niger producing was172.34U·mL-1. The impact of various factors on the enzymatic activity in order as follows:wheat bran-rice ratio> water-solid ratio> the content dipotassium hydrogen>content of ammonium sulfate.(3) For the optimization of solid-state fermentation condition, Aspergillus niger were cultured on the media with the optimum match for producing glucoamylase mention above, then we adopted L9(34) orthogonal test using enzymatic activity of glucoamylase as index to investigate the impact of four major factors:initial pH, incubation temperature, inoculum’s size and incubation time on producing glucoamylase and optimized the optimum condition as A1B3C2D2, namely the initial pH at4, the culture temperature of32℃, inoculum’s size of3%, incubation time of5d. Under these conditions, the enzymatic activity of glucoamylase is227.17U·mL-Heavy-secondary degree of the factors range in order as follows:the incubation temperature> initial pH> incubation time> inoculum’s size.(4) In order to investigate enzymic hydrolysis of konjac fly powder on the basis of the optimum enzyme-producing media and fermentation conditions, we utilized L9(34) orthogonal test to investigate the impact of four main factors on enzymatic effect using enzymatic activity as index and optimized the optimum conditions as hydrolyzing time of2h, the enzymatic temperature of60℃, the dosage of the crude enzyme in2mL/g, pH at4. Under these conditions, the yield of reducing sugar by hydrolysis of the crude enzyme solution to konjac fly powder was42.46%. Heavy-secondary degree of the factors range in order as follows:the dosage of the crude enzyme solution> enzymatic temperature> enzymatic pH> enzymatic time.(5) Through single-factor test, the optimum value of initial sugar concentration, inoculum’s size, fermentation temperature, rotation speed, the initial pH and fermentation time as six main factors affecting alcohol fermentation by pellucid konjac fly powder syrup were determined. Based on the single-factor test of alcoholic fermentation conditions, the factors that have relatively large impact on the alcoholic fermentation (p<0.05) such as inoculum’s size, fermentation time and fermentation temperature were selected as response surface experimental factors. We optimized process conditions of pellucid konjac fly powder syrup alcohol fermentation by response surface test and the results showed the response surface method can be used in regression analysis and parameter optimization of the conditions of alcohol fermentation by pellucid konjac fly powder syrup. Moreover, the regression equation reflecting the relation among the three factors:the alcohol content (Y) and inoculum’s size (X1), fermentation temperature (X2), fermentation time (X3) was obtained as follows:Y=-277.77944-2.90722*X1+16.10000*X2+0.24275*X3+0.15000*X1X2-0.010000*X1X3+0.012500*X2X3-0.037778*X12—0.31000*X22-3.35000*X32 And the regression equation was simplified after deleting non-predominance as follows:Y=-277.77944-2.90722*X1+16.10000*X2+0.24275*X3+0.15000*X1X2-0.31000*X22-0.00335*X32The optimum condition was obtained as follows:the inoculum’s size of11%, fermentation temperature was30.16℃, and fermentation time was76.08h. As validated, the actual alcohol content in alcohol fermentation of pellucid konjac fly powder syrup by determination is10.3%(V/V) in this condition.(6) Dipped a certain amount of oak chips the wine sample by a second distillation and aged wine in a certain temperature for a certain time. Through determining the content of total phenols, tannins, methanol and fusel oil, we analyzed the effect of different aging time, baking degree of oak chip, added amount of oak chip, and aging temperature on aging and determined the optimum aging condition of konjac powder whiskey which was aging time60d, moderate baking degree of the oak chips, added amount of oak chips in2%, and the aging temperature of℃. Sensory indicators, the physical and chemical indicators of konjac powder whiskey brewed in these conditions were in line with the national standard whiskey. |
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