| Under the condition of low temperature in winter,there is often an abnormal temperature with the stacked grain in the Maotai-flavor liquor.In this paper,through the "turning the grain pile" treatment of the abnormal fermentation heap Y,and compared with the normal fermentation heap Z on same workshop.The physical and chemical indicators,enzyme activity,microbial flora structure and volatile flavor substances in fermented grain were studied and analysed correlation between them.In order to clarify the advantages and disadvantages of “turning the grain pile” in the production of Maotai-flavor liquor,it provides a basis for solving the abnormal fermentation.The main results and conclusions are as follows:1.When the stacking fermentation was abnormal,moisture and total acid content were 51.74±0.001%,1.02±0.013g/Kg,respectively,which was higher than the normal fermentation value?50.93±0.07%?0.94±0.0001g/Kg?;reducing sugar,glucoamylase activity,acid protease activity,cellulase activity was 1.41±0.05%,868.38±3.93U/g,5.15±0.45U/g,4.35±0.01U/g,respectively,significantly lower than normal group value?2.73±0.06%?1199.45±7.81U/g?12.85±0.60U/g?6.25±0.05U/g?.“Turning the grain pile” treatment reduced the moisture and total acid content,and significantly increased the content of reducing sugar,and the activities of glucoamylase,?-amylase,acid protease and cellulase.Moreover,the abnormally stacked grain can be restored to normal temperature.2.The main dominant bacteria in the two groups were detected as Lactobacillus,Kroppenstedtia,Bacillus,Lentibacillus and Thermoactinomyces;the main dominant fungi were Candida,Thermomyces,unclassifiedoEurotiales,Thermoascus,Penicillium,Aspergillus and Byssochlamys.3.Compared and analyzed the changes of the main dominant microbe at genus level.The results showed that after “turning the grain pile” treatment,the relative proportion of aerobic bacteria such as Bacillus,Thermoactinomycetes and Lentibacillus increased,but the proportion of anaerobic Lactobacillus has fallen rapidly.There was a significant difference in the proportion of Lactobacillus and Bacillus in stacked grain.The proportion of Lactobacillus in the fermented on the 1st day of accumulation were 4.29%?YD1d?and 2.32%?ZD1d?,respectively,and 21.71%?YD3d?and 1.09%?ZD3d?on the 3rd day;the proportion of Bacillus were 25.83%?YD1d?and 21.55%?ZD1d?,respectively,and the 3rd day was 23.35%?YD3d?and 34.09%?ZD3d?.The proportion of Lactobacillus,after “turning the grain pile” treatment?YD5d?was rapidly reduced to 2.03%,which was significantly lower than ZD5d?21.99%?,while the proportion of Bacillus was 36.50%,higher than ZD5d?36.06%?.Candida accounted for 84.81% in the abnormal stacked grain,after “turning the grain pile” treatment,it accounted for 73.26%.In the abnormal stacked grain,unclassifiedoEurotiales?3.99%?,Thermomyces?4.48%?,Thermoascus?3.36%?,Penicillium?0.02%?,Aspergillus?1.58%?,and Byssochlamys after “turning the grain pile” treatment increased to 7.03%,9.14%,5.56%,0.08%,2.15%,and 1.46%,respectively.These bacteria showed a decreasing trend in the normal accumulation of fermented group,“turning the grain pile” was conducive to the growth of these bacteria.The study found the changes of the main dominant fungal flora were same in the fermented grain of two pits.4.Correlation analysis between species and environmental factors,the results showed temperature and starch reducing sugar were the most important physical and chemical indicators affecting the structure distribution of bacterial flora.The total acid and moisture were the most important physical and chemical indicators affecting the structure distribution of fungal flora.Lentibacillus,Theromactinomyces,Bacillus and Kroppenstedtia were significantly positively correlated with temperature,reducing sugar content and enzyme activity,but Lactobacillus was significantly negatively correlated.Temperature was significantly positively correlated with Candida,but Aspergillus was negatively correlated.Glucoamylase activity was a significant positive correlation with Candida and Thermomyces.Acid protease activity was a significantly negatively correlated with Cystolilobasidium.Cellulase activity was a significant positive correlation with unclassifiedoEurotiales,Thermomyces,Thermoascus,Byssochlamys,Monascus.5.PCA revealed significant differences in the composition and content of volatile flavors in the two group samples.There were significant differences on the 3rd and 15 th day of the fermentation in pit,but were high similarity at the end of the fermentation.Semi-quantitative analysis showed that in the sample of two groups,the highest content of volatile flavor substances was alcohol,followed by esters.“Turning the grain pile” treatment was beneficial to increase the relative content of esters and aldehydes,and reduced the content of propanol and acetic acid,and was beneficial to the formation of furfural and ethyl lactate.To sum up,this study showed that the growth state of aerobic bacteria had a significantly impact on the fermentation process of the Maotai-flavor liquor.When the growth of aerobes was poor,the stacking fermentation was abnormal with lower temperature,the reducing sugar content decreased,the enzyme activity decreased,and increased the moisture and total acid content.“Turning the grain pile” treatment can reverse the adverse fermentation conditions,effectively improved the growth of aerobic bacteria,and improved the diversity of fungal species,increased the relative content of esters and aldehydes,thereby making the accumulation of fermentation was more sufficien and preparing for fermentation in the pit.In this paper,the microbial,physicochemical,enzyme activity and volatile flavors of the Maotai-flavor liquor accumulation and fermentation in the wolfberry before and after the “turning the grain pile” treatment,It is proved that this measure can effectively improve the accumulation and fermentation anomaly in the low temperature environment,and will be helpful to better control the accumulated fermentation process and provide reference for production of Maotai-flavor liquor. |
PDF Full Text Request