Research On Arapid Detection Method For Main Microbial Activity During Storage Of Daqu In Liquor

"Daqu is the bone of wine", Daqu was probiotics, the microorganism is very complex, its quantity scale, including the kinds of microorganism and changing rule will directly affect the fermentation process of liquor, and also decide liquor flavor types style. Daqumicrobes mainly havethree categories: bacteria, yeast and mould.For Daqu liquor, this paper studied the properties and activities in the process of storage, and rapid survival method of main microbes in Daqu liquor have been set up, in order to establish a simple and rapid count method for evaluating microbial survival based on fluorescence staining.In this paper, firstly, DAPI and PI fluorescent dye are used for, the lactic acid bacteria and yeastas the research object, and the DAPI and PI in the concentration of fluorescent dyes and appropriate dyeing time are also determined, to establish a simple and rapid detection method of bacteria and yeast in Daquliquorbased on fluorescent staining method.At the same time through a traditional method to count of the two kinds of flavor of Daqusamples of bacteria and yeast, and compare the new method,to prove the availability of the new method established.We also compares the real-time fluorescent quantitative PCR analysis with microbialcount method based on fluorescence staining, and further verify the feasibility of the fluorescent staining method. During the actual inspection, select samples of Nong-flavor ZhiJiang Daqu andJiang-flavorBeidacangDaqu, and the different storage temperatures ZhiJiang daqu and BeidacangDaqu of different storage time tracking detection, finally a perfect testing methodhas been set up.The main research conclusions are as follows:Experiments prove that the simple and rapid microbial count method based on DAPI/PI fluorescence staining on pure bacteria effect is good, high stability, and selectivity of bacteria is stronger, the background is also clean, and it is advantageous to be counted, and then we have to determine the optimum dying conditions, DAPI dye concentration in 10μg/moL, dyeing time for 30 min, PI dye concentration in 50μg/moL, dyeing time for 1hour,fluorescence dying effect is better.The methodofdetection microbial activity of Daqu liquor have been established through the experiment, and determines the method detection limit:5×105cfu/mL(yeast), 5×105 cfu/mL(bacteria).Compared with national standard method, operating time was short, generally only need 3 hours to complete the experiment;At the same time, it can also be verified that the accuracy of the fluorescent staining, fluorescent staining test results are higher than the national standard test.Compared with real-time fluorescent quantitative PCR method, two detection methods of P value was 0.125, was greater than 0.05, their differences was no significant.Tracking and analyzing the different storage way for various physical and chemical indexes of Daqu liquor and microbial indicators by using the new method. The BeidacangDaqufor storaging three years of the bacteria of survival rate is 85%; The ZhiJiang daqu for storagingunder room-temperature of the yeast of survival rate is 82%.