Study On Quality Improvement And Harm Reduction Of Microbial Fermented Oral Tobacco Raw Materials

With the development of economy,the harm of smoking was gradually realized by the public and the new smoke-free tobacco products would like to be introdued.Snuff cigarette,one of the new substitutes for cigarette,has been developed by many cigarette companies under the international environment for control of tobacco.Comparing to the combustion way of traditional cigarettes,the Snuff cigarette would be put into mouth directly.Therefore the traditional tobacco leaves which will produce a greater pungent taste and irritation is not suitable for direct production of Snuff cigarette.Moreover,tobacco contains nicotine,unique nitrosamines and other harmful substances,which pose a threat to human health.As a result,it is necessary to adopt appropriate technology to improve the suitability and quality of tobacco raw materials.This dissertation aims to improve the quality of tobacco raw materials and reduce the content of nicotine and specific nitrosamine by the fermentation of tobacco raw materials with foreign microorganisms.The experimental study on the fermentation of the prepared tobacco raw materials with compound bacteria was also carried out.The results are shown as follows:(1)The basic chemical components of tobacco(cv.Yunyan 87)leaves of different grades produced in Qiandongnan Prefecture of Guizhou Province were analyzed by continuous flow analyzer.It was found that the middle and upper leaves were suitable for Snuff cigarette.Bacillus amyloliticus(GUHP86)and(B01)had the ability to enhance the sensory properties of Snuff in a shortened fermentation time.For sensory properties from nose,satisfaction,taste characteristics,bad breath,mouth mouth,and agglomeration of tobacco during fermentation,it can be known that the optimal conditions for GUHP86 fermentation were: the inoculation quantity of 20%,sugar salt solution of 20%,fermentation temperature 37°C,fermentation time of 15 days.The optimal fermentation conditions B01 to ferment the for tobacco raw material was: inoculation amount of 30%,sugar and salt solution of 25%,fermentation temperature at 37°C,and fermentation time of 15 d.(2)The tobacco leaves were fermented by GUHP86 and B01 under the optimized conditions,extracted by SDE,concentrated by K-D method,and analyzed by gas chromatography triple quadrupole tandem mass spectrometry(GC-MS-MS).The changes of aroma components before and after fermentation were determined,and the changes of aroma components before and after fermentation were compared.The results showed that the types and relative contents of the aromatic substances were changed after the fermentation by these strains.In addition,some substances with unique fragrance were produced after fermentation.The fermentation have the function of flavor enhancement,GUHP86 produced more aroma compounds than B01.After GUHP86 fermentation,9 kinds of aroma substances were added,mainly aldehydes,ketones and esters,and 7 kinds of irritating enoids and alkanes were reduced.After B01 fermentation,six alcohols and ketones were added and five substances were decreased.The fermentation could help to obtain more harmonious,complex and strong aroma,less irritation,rich taste and better flavor tobacco raw materials.(3)The tobacco leaves were fermented by GUHP86 and B01 under the optimized conditions.The contents of nicotine and two specific nitrosamines,nitrosamine n-nitrosodimethylnicotine(NNN)and 4-methylnitrosamine-1-3-pyridyl-1-butanone(NNK),before and after fermentation were determined by gas continuous flow analyzer and liquid chromatography tandem mass spectrometry(LC-MS-MS).The result showed that both of GUHP86 and B01 could reduce nicotine and nitrosamines,and the best fermentation time for two microorganisms was10-15 d.GUHP86 showed different ability to degraded the amount of nicotine from different part of tobacco,which is in the order of 50.78% for the upper part of tobacco,40.89% for the central part of tobacco,and 19.46% for the the lower part of tobacco.Comparing to GUHP86,B01 showed a lower ability to degrade the amount of nicotine,which is in the order of 44.36% for the upper part of tobacco,38.43% for the central part of tobacco,and 15% for the the lower part of tobacco.The degradation rates of NNN by GUHP86 were 28.15%,56.73% and 64.39% for the lower leaves,middle leaves and upper leaves of tobacco,respectively.The degradation rate of NNK was 33.33%% in the lower leaf,59.28% in the middle leaf and 63.73% in the upper leaf.The degradation rate of NNN by B01 was 53.23% in the lower leaf,54.86% in the middle leaf and 55.60% in the upper leaf,and the degradation rate of NNK was41.67% in lower leaves,55.43% in middle leaves and 65.68% in upper leaves.(4)The co-fermentation by GUHP86 and B01 could degrade 47.37% of nicotine in tobacco and improve its sensory properties,which were higher than that from single fermentation.Taking the nicotine content and sensory properties as evaluated base,the change of nicotine content in tobacco raw materials during fermentation was monitored,and the sensory score was used to determine the fermentation conditions of co-fermentation.It can be found that the nicotine content in tobacco raw material can be significantly changed under different strain ratio,inoculation quantity,sugar,salt solution.The optimized conditions for co-fermentation was starch GUHP86 and B01 ratio of 3:1,inoculation amount of30%,sugar salt solution of 20%,fermentation time of 15 d,and temperature of 37°C.Under the optimized conditions,the nicotine content in tobacco raw material was 1.51%,which can endow the mouth smoke tobacco with 94 sensory score.