Changes in microbial composition during flue-cured tobacco aging and their effects on chemical composition: a review

The aging is a crucial stage in tobacco processing, which contributes to the reduction of impurities and irritation, and the stabilization of the internal chemical composition of the leaves. However, it usually takes a long time (2-3 years) for the nature aging process of tobacco (20 °C-30 °C, relative humidity of 65-75%), which seriously affects the processing efficiency of tobacco. Microorganisms play an important role in the change of chemical composition and characteristic aromatic substances of tobacco. Acinetobacter, Sphingomonas Aspergillus, Bacilli, and Pseudonocardia is the main microorganism in the aging process of tobacco, which increasing the aromatic substances (such as alcohols, ketones, and esters) by the action of the enzymes and metabolites, and degrade the harmful components (such as alkaloid, nicotine and nitrosamines in tobacco). This review systematically summarizes recent advancements in understanding the primary microbial composition and the changes in chemical composition during tobacco aging. This knowledge is helpful for screening functional strains, and control the process of tobacco aging by the inoculation of these strains.