Study on influence of processing strength on flue-cured tobacco leaf quality in the threshing and redrying process
To improve the technological level of threshing and redrying and quality of products, the influences of processing strengths (steam moistening, steam mixing water moistening, slow redrying with low-temperature, high-temperature redrying) on the qualities of flue-cured tobacco leaves were studied in this paper. The results showed that the variation coefficients (Cv) of moisture and appearance colors fluctuations for redried lamina of steam moistening and slow redrying with low-temperature were 3.24%, 9.76% (L), 7.82% (a) and 8.39% (b*), respectively. The uniformities were increased by 42.65%, 16.44%, 46.73%, 3.12% compared to steam mix water moistening and high-temperature redrying, respectively. Compared to flue-cured tobacco leaves, the colorants contents were decreased by 8.13% and 18.29% via steam moistening and steam mix water moistening, respectively, while the polyphenol contents were 5.05% and 8.99%. Similarly, the colorant contents were decreased by 2.12% and 5.94% via slow redrying with low-temperature and high-temperature redrying, while the polyphenol contents were 15.63% and 19.46% compared with moistening tobacco leaves, respectively. However, the total contents of flavor precursors in tobacco leaves processed via steam moistening and slow redrying with low-temperature were higher than those by steam mix water moistening and high-temperature redrying, improved the flavor richness, aroma quanlity and aftertaste of redried lamina. Therefore, the steam moistening and slow redrying with low-temperature were advantageous to improving the qualities of redried lamina in the threshing and redrying process, providing a theoretical basis for the characteristic processing techniques of the threshing and redrying.