Purpose To explore the effect of nitrogen filling-oxygen reduction storage on the aging quality of formula and re-dried tobacco strips.
Methods In a Guangdong aging warehouse, tobacco leaves were stored using nitrogen-filled and oxygen-reduced (CD) treatment and conventional sealing (CG) methods. The changes of chemical composition, aroma components, biological enzymes, tobacco microbiota and sensory quality of formula and re-dried tobacco strips were compared after aging for 6, 9, 12 and 14 months.
Results During the aging process, the contents of total sugar, reducing sugar, potassium, chlorophyll degradation products and total aroma amount all exhibited a declining trend; the contents of maillard reaction products and neutral aroma components gradually increased; however, the contents of carotenoid degradation products and cembranoids degradation products first increased and then decreased. Compared with CG treatment, the contents of total sugar, reducing sugar, total nitrogen, potassium, megastigmatrienone, linalool, furfural and 5-methylfurfural, and biological enzymes activities of tobacco leaves under CD treatment were higher; the sugar-to-nicotine ratio and nitrogen-to-nicotine ratio were closer to the standards of high-quality tobacco leaves; and the various aroma components and total amount were also relatively higher. The pectase activity of tobacco strips under different treatments initially increased and subsequently decreased, but the activities of α-amylase, cellulase and neutral protease under CD treatment showed an increasing trend. At 14 months of aging, the activities of α-amylase, pectase and neutral protease under CD treatment were extremely significantly higher than those in CG treatment by 12.45%, 38.28%, and 49.55%, respectively. The relative abundance of dominant bacterial genera such as Sphingomonas, Methylobacterium-Methylorubrum and Epicoccum in CD-treated tobacco leaves was relatively higher, which was beneficial for quality transformation; Massilia, Enterobacter and Alternaria that had negative function to aroma component transformation were obviously reduced. In sensory quality, the fineness, irritation and dryness of tobacco leaves treated by CD treatment were 3.17%, 5.00% and 5.00% higher than those of CG treatment, respectively.
Conclusion Nitrogen filling and oxygen reduction storage method inhibits the growth and reproduction of some pathogens in tobacco leaves to a certain extent, maintains the activities of biochemical enzymes and some beneficial microorganisms, regulates the aging rate of tobacco leaves, makes the proportions of intrinsic chemical components in tobacco leaves more balanced, increases the aroma components, makes the sensory quality better. This aging method has certain advantages in high humidity and high temperature areas such as Guangdong.
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