Effects Of Accumulation Condition On Aroma Quality Of Sesame-flavor Liquor

It can provide practical and theoretical guidance for practical production and precise control of pilot scale accumulation and cellar fermentation process through studying the effect of sesame-flavor liquor accumulation on the cellar fermentation process and liquor quality.The perfect temperature controlled system of accumulation and cellar fermentation was established in the laboratory on the basis of tracking the actual accumulation process in summer and winter.Then,the microbial community succession,physical and chemical index,enzyme activity accumulation and flavor substance synthesis in different accumulation process were studied under the condition of different accumulation temperature.Furthermore,the effect of different accumulation fermented grains on cellar fermentation process was studied.The main results are as follows:(1)Due to the difference of climate and environment,the effect of accumulation was different in summer and winter of actual production.On the whole,the number of yeast and mold in summer was higher than that in winter during accumulation process,reaching 8.48,7.87 lgCFU/g,respectively.But the number of bacteria was slightly different.Additionally,the accumulation of glucoamylase and acid protease activity were higher than that in winter.(2)Under the condition of different accumulation temperature,the microbial growth and metabolism rate of each sample was different,which resulted in the different accumulation results.On the one hand,the variation trend of microorganism in each sample was similar,but there were significant differences among different microbes.Combined with the traditional plate culture method and qPCR to monitor the number of various microorganisms in fermented grains,the results showed that the difference of accumulation effect among samples was mainly reflected in the number of yeast and mold,followed by the number of total bacteria.On the other hand,each sample went through different accumulation process,which the physical and chemical indexes of fermented grains showed different changing trajectories.Finally,the accumulation of enzyme activity in each sample was positively correlated with microbial enrichment.Besides,the high temperature accumulation environment can promote the synthesis of flavor substances except for metabolic secretion of microorganisms,especially the esters and pyrazines flavor substances.(3)The temperature of accumulation was too high and easy to accumulate too much.Such as sample 1 and sample 2,the initial microbe quantity of fermented grains of cellar fermentation was too high,which the number of yeast,mold and total bacteria was higher than 9.04 lgCFU/g.After entering the cellar,the grain acidity increased too fast,especially the acetic acid content increased rapidly and the alcohol fermentation was seriously inhibited.Ultimately,the liquor yield was low and liquor quality was unqualified,which was abnormal fermentation.In addition,although the accumulation temperature was different between sample 3 and sample 4,but the microbial quantity was in the suitable range,which the number of yeast and mold was 8.44~8.68 lgCFU/g and the the number of total bacteria was 8.45~8.90 lgCFU/g.Finally,the accumulation was suitable.After entering the cellar,microbial alcohol fermentation and esterification were carried out normally.Finnally,the liquor yield was normal and liquor quality was qualified,but the liquor style was different.However,due to the accumulation temperature of sample 5 and sample 6 was too low,which the initial microbial quantity was low and the accumulation of flavor substances was less.The quantity of yeast and mold was only 7.87 ~ 7.98 lgCFU/g,but the number of bacteria was close to other samples.After entering the cellar,although the alcohol fermentation was carried out normally,the liquor yield was lower.Meanwhile,the scorched incense and sesame flavor of liquor was weak.(4)Combined with the results of accumulation and cellar fermentation of each sample,the results showed that: the air humidity was controlled to 45~50% and the top temperature at 48.4~51.8? during accumulation process,which can ensure that accumulation carried out stably.At the end of the accumulation,the number of yeast was 8.44 ~ 8.68 lgCFU/g,the number of mold was 8.46 ~ 8.55 lgCFU/g and the number of total bacteria was 8.45 ~ 8.90 lgCFU/g.Further more,the activity of glucoamylase was 170.52~195.19 U/g and the activity of acid protease was 303.52~349.87 U/g.Ultimately,the effect of accumulation was more suitable,which can ensure the smooth progress of alcohol fermentation and esterification after entering the cellar.