Construction of green flue-cured tobacco strips aging technology based on four-stage controlled atmosphere method
Aging of flue-cured tobacco strips plays an important role in improving the quality and use value of tobacco. Natural aging is the most widely used storage method at present, but there are still some problems, such as shorter suitable aging duration, easy occurrence of mildew and storage pests and using chemical pesticides for fumigation. In this study, we established a new controlled-atmosphere (CA) aging technology which divided the aging period into four stages according to the different purposes. The first stage is based on natural aging, and the latter three CA stages were CA pests and mildew control, CA aging and CA quality maintenance stage, respectively. The sensory quality, appearance quality, carotenoid content and pH value were compared between natural aging and four-stage CA aging using flue-cured tobacco strips from different tobacco production areas. The results showed that the tobacco beetles and mildew can be effectively controlled using low oxygen concentration (≤ 2 %) for 90 days. After this, the oxygen concentration was adjusted to 7 % ~ 9 % for more than 120 days. This CA aging stage can significantly improve the sensory quality and delay the over-darkening of tobacco strips. Lastly, reducing the oxygen concentration below 2 % and maintaining it until the tobacco stack was opened. The technology not only improved the tobacco aging quality, but also extended the suitable aging duration by at least 15 months compared to the natural aging. The decrease rate of carotenoids and pH values were also delayed. The key periods of tobacco aging duration were subdivided and chemical pesticides were avoided in our study. The four-stage CA aging technology supplied a green, high-quality and environmentally friendly system for tobacco strips storage.