Generic Fermentation Technology Parameters and Process Control for Cigar Tobacco Leaves

Purpose To study and validate the technical parameters for cigar leaf fermentation, providing data support for precisely regulating the fermentation process of cigar leaf.

Methods The common technical parameters such as temperature and humidity fields, initial moisture, sealing material and stack size were tested, and the smell was evaluated.

Results The temperature at the center of the stack was significantly higher than that around it, while the relative humidity exhibited an opposite trend. Both fermentation temperature and intensity gradually decreased over time. In the early stages of fermentation, mold growth was likely to occur in the cutters and upper leaves due to uneven return tide and excessive localized moisture. High moisture content and larger stack sizes could accelerate fermentation, while effective sealing materials could improve fermentation quality. The aroma of tobacco leaves evolved from a hay-like scent before fermentation to rancid, ammoniacal odour, and spicy notes during the midstage, ultimately developing into sweet, spicy, sour, and fruity flavors in the late stage of fermentation.

Conclusion The core parameters for bulk fermentation technology are the control of moisture content and fermentation temperature. The initial moisture of tobacco leaves should be moderate in the early stage, high in the middle stage, and low in the late stage. The upper temperature limits for the lower leaves, cutters, and upper leaves of filler should be 45, 48, and 55 ℃, respectively; while wrapper tobacco leaves should ideally be around 5 ℃ lower. Key indicators for assessing fermentation quality include fermentation duration, high-temperature cycles, heating rate, flavor purity, oil content, color, combustibility, and ash characteristics.