Effects Of Spraying Compound Biological Agents On Quality And Microbial Diversity Of Tobacco Leaves In Southern Shaanxi During Modulation And Redrying Stages

One of the most important economic crops in southern Shaanxi province is flue-cured tobacco.The advantages of tobacco leaves in Shaanxi include primarily good maturity,uniform and vivid color,and generally coordinated primary chemical components due to the suitable ecological environment and proper cultivation measures.The drawbacks are that wood gas is heavier,smoke concentrations are slightly lower,and the chemical composition of some macromolecules is slightly higher.As a result,it is an important means of emphasizing the quality characteristics of Shaanxi tobacco leaves by using biological preparation technology to further improve the quality of tobacco leaves during the curing and aging stages of flue-cured tobacco,and the research of this technology in Shaanxi tobacco leaves is insufficiently systematic.As a result,the Shaanxi SXC-4 compound biological agent that contains different hydrolases,oxidoreductases and aromatizing bacteria,was used to investigate the effects of various material ratios on the conventional chemical components,polyphenols and other special chemical components,neutral aroma components,and microbial diversity of flue-cured tobacco during the curing and redrying stages of flue-cured tobacco by atomization spraying.The main conclusions are as follow.1、Spraying Shaanxi SXC-4 compound biological agent in the modulation stage has a significant effect on the chemical quality of flue-cured tobacco.It is beneficial to the degradation of nitrogen-containing compounds such as total nitrogen and protein,starch,lignin and pectin in tobacco leaves,thereby increasing the content of sugar compounds such as total sugar and reducing sugar,free amino acids,Amadori compounds and aroma substances,so that the chemical composition of tobacco leaves is more coordinated.Among them,the degradation effect of pectin and lignin under T1 treatment(5 % material ratio)was better,which decreased by 5.9 % and 58.6 % respectively;the content of free amino acids and aroma components increased by 6.5 % and 51.8 % respectively under T2 treatment(4 % material ratio).The content of Amadori compounds increased by 11.2 % under T3treatment(3 % material ratio).By improving the coordination of chemical components of tobacco leaves,spraying compound biological agents in the modulation stage can increase aroma quality and aroma quantity,improve permeability,reduce offensive odor and irritation,improve concentration and strength,and significantly improve sensory quality.2、The microbial diversity of tobacco leaves treated with compound biological agents in the modulation stage was higher than that of the control,and the dominant bacteria Proteobacteria,Firmicutes and Actinobacteriota were greatly improved.The differential genera were Pseudomonas,Methylobacterium,Kineococcus,Aureimonas,Allorhizobium,and Nocardioides.3 、 The effect of spraying compound biological agents on improving the quality of tobacco leaves was different in the modulation stage and the redrying stage.Compared with the control,they could promote the transformation of chemical components of flue-cured tobacco,increase aroma substances and improve the sensory quality of tobacco leaves.Spraying compound biological agents in the redrying stage has a more obvious effect than in the modulation stage.The significant effect of redrying stage was reflected in the decrease of starch content,nicotine content and organic acid content by 17.2 %,5.7 % and 7.4 %respectively,and the aroma,permeability,sweetness and concentration of tobacco leaves were improved.The significant effect of the modulation stage is reflected in the increase of the Amadori compound content by 2.6 %.The increase of aroma,permeability,sweetness and concentration of tobacco leaves was more obvious;the significant effect of the modulation stage is reflected in the fact that the content of Amadori compounds can be increased by 2.6 % after aging,and the aroma,offensive odor and irritation of tobacco leaves are obviously improved.In general,spraying compound biological agents during the redrying stage is more advantageous for enhancing the sensory quality and quality of flue-cured tobacco than during the modulation stage.In conclusion,the transformation of macromolecular substances in tobacco leaves was promoted,the bacterial diversity of microbial dominant strains was improved,the chemical composition coordination of tobacco leaves was improved,the aroma quality and quantity were improved,and the sensory quality of flue-cured tobacco was improved through the use of compound biological agents in the curing and redrying stages of tobacco.Spraying Shaanxi SXC-4 compound biological agents with 3 % and 4 % material ratio in the stage of modulation and redrying can be used as the main technical measures to improve the quality of tobacco leaves in southern Shaanxi and highlight the characteristics of tobacco leaves in Shaanxi.