Abstract:
To scientifically optimize the curing process for tobacco leaves in different regions, this study utilized IoT technology to collect dry-bulb and wet-bulb temperature data from 779 curing batches across typical production areas with distinct flavor types: fresh-sweetness, honey-sweetness, burnt-sweet and burnt, fresh-sweet and honey-sweet. The analysis focused on process indicators including time management and humidity control during the curing of middle and upper leaves in different fragrance ecological regions. Building on the interrelationships between curing parameters, the feasibility of predicting process indicators was explored. Key findings include: (1) Median total curing duration across fragrance ecological regions ranged 170-220 h. Upper leaves generally required 5-15 h longer total curing and yellowing period duration than middle leaves. Time allocation ratios for yellowing, color-fixing, and stem-drying periods averaged approximately 45%, 35%, and 20% respectively. The burnt-sweet and burnt fragrance ecological region showed extended total curing and yellowing periods, contrasting with the fresh-sweet and honey-sweet fragrance ecological region. (2) Wet-bulb temperature in some flavor regions exhibited an N-shaped trend (initial rise → decline → secondary rise). The fresh-sweet and honey-sweet fragrance ecological region maintained higher initial wet-bulb temperatures (1-3 ℃ above others) with greater stability. Upper leaves generally showed lower wet-bulb temperatures than middle leaves, with significant differences emerging from late yellowing period in the burnt-sweet and burnt fragrance ecological region. (3) In most fragrance ecological regions, wet-bulb temperature during late yellowing to early color-fixing periods significantly correlated with time management: temperature decrease (increase) during late yellowing corresponded to shortened (extended) yellowing duration and extended (shortened) color-fixing duration. (4) The prediction model of wet-bulb temperature from the color fixing period to the stem-drying period can be established by using the curing process data of different flavor areas and stepwise regression analysis method, and the determination coefficient is above 0.65. In summary, there are obvious differences in the regulation of tobacco curing process in different areas. The large fluctuation of wet bulb temperature from the late yellowing period to the early color fixing period and the low wet bulb temperature in the color fixing period are the common problems in the curing process of most aroma-type areas. The regulation of wet bulb temperature from the late yellowing period to the early color fixing period is closely related to the process management of the curing process, which should be paid attention to.