The Study On Tobacco Microbial Flora In Qinling Mountain And Compound Microbial Agent Improve The Quality Of Tobacco Leaves

Microorganisms play an important role in the process of tobacco fermentation.Microbial fermentation can improve the aroma quality of cigarettes to reduce “green” taste and irritating odors,and give tobacco a fuller,purer and more pleasant smell.The study used fresh tobacco leaves,baked leaves and soil from Ankang,Hanzhong,and Shangluo in the Qinling mountains to separate microorganisms.Screening targets for the next tobacco fermentation based on their ability to degrade starch,pectin,cellulose,xylan,protein,and N-nitrosoamines;.Sensory evaluation and GC-MS analysis the influence of the fermented tobacco test on tobacco aroma quality.Screening microorganisms with tobacco aromatization again,and mixed those to produce a microbial preparation in which the tobacco quality was significantly improved.The results of this study were as follows:1.A total of 36 samples of tobacco leaves and soil was collected from the different three cities in the Qinling mountains.A total of 820 strains were obtained from 31 samples,including 471 strains of bacterium,160 strains of molds,114 strains of yeasts,and 75 strains of actinomycetes.Bacteria are dominant microorganisms,accounting for 57.44% of total microorganisms.There are fewer molds and yeasts than bacteria.The number of actinomycetes was the lowest,and 93.33% of actinomycetes were screened from rhizosphere soil samples.Comparing the microbial richness of different sampling sites,soil >fresh leaves> baked leaves.Middle of fresh tobacco leaves > upper part > lower part,middle part of flue-cured tobacco leaves > lower part > upper part.In the three districts of Ankang,Hanzhong and Shangluo,Shangluo had the most abundant types of tobacco,with an average of 18.47 strains,followed by Ankang,and Hanzhong least.The comparison of microbial richness of different varieties of tobacco showed that Yunyan 87 and Yunyan 99 are the most abundant,and Yunyan K36 and Yunyan97 have lower abundance.2.The number of strains those can degrade protein,starch,xylan,cellulose,pectin,and N-nitrosoamines accounted for 56.82%,16.83%,13.17%,14.88%,5.49%,and 25.98% of the total number of strains,respectively.There were 120 strains that could degrade protein and starch simultaneously,12 strains that could simultaneously degrade protein,starch andpectin,and 42 strains that could degrade starch,protein and cellulose at the same time.Five strains were isolated from the soil with ability of degrading starch,pectin,protein and cellulose.3.The results of sensory evaluation show that there are 14 strains that have the effect of increasing aroma,of which 7 strains such as xh281,xa623,xs617,xh684,xh634,xh632,and xh217 have stronger effect,and the other strains had a flavoring ratio of more than1.01%,which significantly improved the smoke concentration,sweetness and irritation.The protein degradation index of strain xa623 was 2.00,and the indexes of smoke state,aroma quality and aroma amount were 8.00 points,8.25 points,and 7.25 points,which were higher than the control and other samples.The starch and cellulose degradation index of xh684strain was 1.1 and 2.0,respectively,and it also had the function of degrading N-nitrosoamines.The content of nitrogenous compound after treatment was reduced by28.62%compared with the control,and the scores of irritation and comfort index were 7.50,7.25.,better than the control and other samples.The results showed that amylase,cellulase and strains capable of degrading N-nitrosamine had a great influence on the irritant and comfort indexes of smoke.4.The correlation between the aroma components of fermented tobacco leaves of each strain was analyzed by GC-MS and sensory evaluation.The results showed that the sensory evaluation index was weakly correlated with alcohol,nitrogen compounds and ketones.Ester compounds were significantly negatively correlated with smoke state and gas,and were significantly negatively correlated with aroma,sweetness and comfort.In the smoke,resibufogenin and Picrotoxinin has toxic and spicy smog,When the content is higher than that of dimethyl phthalate and dihydro kiwi lactone,the quality of tobacco such as smoke state,aroma and sweetness is degraded.Aromatic benzyl alcohol and phenylethyl alcohol are the most frequent alcohol aroma substances with a concentration is less than 10μg/g tobacco leaves.At low concentrations,they still have a positive positive effect on tobacco aroma.Ketones are a class of compounds with rich abundance and content in tobacco aroma components.The types and contents of ketone compounds in flue gas are relatively rich,accounting for 20%-30% of the constituents of flue gas.Solanone,megastigmatrienone and4-oxo-α-lonone are closely related to tobacco aroma quality.Nitrogen compounds are the most abundant compounds in flue gas,accounting for more than 55% of the total smoking gas.Fermenting tobacco with a strain having the ability to reduce nitrite can reduce the content of nitrogen-containing compounds and reduce tobacco irritation.5.The strains xh217,xh281,xs617,xa623,xh632,xh634,and xh684 were prepared in four different proportions and the fungi were evaluated after the tobacco leaves were fermented.The results showed that when the treatment ratio was 1:8:4:2:1:4:3,the sensory score was 2.95% higher than that of the control,and multiple individual indicators were superior to the control and other samples.The inoculant can significantly improve the quality of tobacco.Compared with the control,the state of the flue gas is good,the exquisiteness is improved,the aroma quality and aroma amount are improved,the sweetness is increased,and the flue gas has a moist sensation,but the irritantness is heavy.