The Study On The Succession Law Of Physicochemical Index And Microbial Community In The Preparation Of Luzhou-flavor Daqu

Daqu plays an important role in the production process of Luzhou-flavor liquor in china.In order to fully understand the change and interaction of microbial community during the process of daqu fermentation, and tits correlation with indicators of Daqu, especially the function of the microbial community in daqu and multiple enzyme system. This experiment takes the samples of Luzhou Daqu in the various stages of fermentative process,totally12samples, as the experimental object, using the continuous flow chemistry analyzer and PCR-DGGE technology to study the change law of physicochemical and biochemical index, and the microflora multiplicity of the Luzhou-flavor Daqu in the fermentative process. The results indicate that:1. During the process of Daqu fermentation, the physical and biochemical index is in a state of constant change, and show that the complexity of the relationship between the metabolism of microorganism.The results of data analysis show as follow. First, during the process of Daqu cultivate,total acid, reducing sugar content rise at first and lowered later,when it gets into the storage period,both of them began to recover, and then all slow down; Amino acids, keep rising trend until it get into the storage period, the rising rate becomes slow; Starch content keep declining, and has a minimum in the20th day, then the checkout amount recovered slightly. Second,during the period of bacteria culture of daqu, saccharifying, liquefaction, esterifying power are first increased and then drop, especially saccharifying power has a biggest drop in, when it get to the storage period, all of them recovered slightly, and later stability at a higher level. And the protein resolution increased at first and then decreased, and has a maximum in the40th day, then decreased slightly.2. The PCR-DGGE profiles of Daqu microbial community show as follow. First,during the process of Daqu fermentation, the band abundance and dominance of fungi and yeast community diversify and changing frequently, and exist a phenomenon of community structure succession. There are7～17and5-16clear bands respectively in the profiles of fungi and yeast. Overall, the species and quantity of fungi and yeast are cumulative, by the period of cultivate and storage. Second, in the whole process, the community structure of prokaryotic microbial also has a big change. There are7-17clear bands in the profiles. Diversity index rises as wave-like trend and finally form a stable bacteria flora.3. In the process of Daqu fermentation, the analysis of correlation between physicochemical and biochemical indexes indicate as follow. The total acid and reducing sugar are significantly positive correlations. Reducing sugar and saccharifying power are positively correlative.The content of amino acid is significant positive correlative with protein decomposition, esterifying power and liquefying power, and negatively correlate with starch content. The saccharifying power and esterifying power was significantly positive correlative. Esterifying power, liquefying power, protein resolution are very significant positive correlative between each other. Show that the complexity of the relationship between the metabolism of micro organism, comprehensive and particularity.4. In the process of Daqu fermentation, the analysis of correlation between physicochemical, biochemical indexes and Daqu Microbial community indicate as follow. First, in the process of Daqu fermentation, the diversity of Fungi and yeast are negatively correlative with total acid, reducing sugar and starch content. Especially, the correlation coefficient of yeast and total acid is-0.58, a strong negative correlation, show that the growth of yeast is greatly influenced by total acid content. The saccharifying power, liquefying power, protein decomposition have a significantly correlation with the diversity of fungi, and that is show that eukaryotic microbiology play an important role in the production of biochemical enzymes in daqu. The diversity of yeast also has a significant correlation with the esterifying power and protein decomposition, and so it may play an important role in the production compound flavoring materials of daqu. Second, prokaryotic microbial are negatively correlative wrth reducing sugar and starch content, and are positively correlated with other Daqu index. Especially, the correlation coefficient of total acid content and the prokaryotic microbial diversity is0.82, that is a strong positively correlation. And the protein decomposition and the prokaryotic microbial diversity also have a good correlation.