Study Of Enzyme And Main Composition Changes In The Process Of Post-fermentation Of Mucor-type Douchi

Mucor-type Douchi was deeply loved by people for unique flavor and nutritive value. In the process of fermentation, Mucor-type Douchi can produced all kinds of enzymes to hydrolysis of proteins into small molecular peptides, amino acids and various kinds of aroma components by microorganisms, increased nutrition and flavor substances. This article determined the optimum conditions of Mucor-type Douchi by different technological parameters in the process of fermentation; The changing of main components and protein hydrolysate of Mucor-type Douchi were studied by SDS-PAGE and reverse HPLC in the post-fermentation process, the correlation of different indicators and hydrolysate of protein was analysed; Semi-quantitative detection the extracellular enzyme activity of each growth stage of Mucor by API ZYM system, then leucine aminopeptidase of Mucor was coarse purification by fractional precipitation with ethanol and its hydrolysis characteristics was pilot studied. The results as follows:1.In the Pro-fermentation process, the optimal process parameters was 15℃,64h,7% inoculum size and 45%moisture content. Under these conditions, hyphae vigorous growth, produce a large number of spores, the total number of mold colony was 2.1×107CFU/g, total protease activity was 103.33 U/g and cellulose activity reached 1.87 U/g. The optimum condition in post-fermentation were salinity 9%, alcohol content 5%, fermentation temperature 45℃,40d. Under the optimum conditions, the scores of sensory evaluation and the physical and chemical index were 14 and 8, respectively. The amino nitrogen of the product reached 0.69%, total acid was 1.95%, total protein was 35.81%and reducing sugar was 3.60%.2. The moisture and protein content was changed little,remain at around 56%and 35% respectively; content of reducing sugar increased first, then reduced, the highest content was 4.53%; The content of total acid and free amino acid was increased gradually, then leveled off, reached the highest at 42d,1.67%and 3.30%, respectively; amino acid nitrogen reached the highest at 35d,0.72%; Browning intensity increased gradually, the maximum was 0.69 at 42d.The molecular weight of the final product by proteolysis mainly between 11-20KD, macromolecular protein degraded into small molecules rapidly and the composition polypeptide was changed significantly between Od to 7d,the content of peptide was changed obviously between7d to 42d. Further analysis showed that, total acid, reducing sugar, browning intensity index were all affected the formation of protein hydrolysate, the degree of positive correlation was in the following order:total acid> browning intensity> reducing sugar.3. Mucor in the process of growth can produced 7 kinds of extracellular enzymes, such as alkaline phosphate, esterase C4, esterase lipase C8, leucine arylamidase,phosphatase acid, naphthol-AS-BI-phosphohydrolase and N-acetyl glucosamine enzymes. The longer the incubation time, the bigger the enzyme activity;The leucine aminopeptidase enzyme activity bycoarse extract was added into Douchi,and without the enzyme were compared,The result shows that the content of total free amino acid increased 13.29% after the leucine aminopeptidase enzyme added, and the leucine aminopeptidase promote formation the decomposition product of protein.