This invention discloses a curing process for the upper tobacco leaves of Yunyan 87 based on the synergistic regulation of yellowing and color fixation. The yellowing period is divided into three stages: in the early stage, the temperature is increased at 0.8~1.2℃ / h to 36~38℃ (wet
bulb 31~35℃), and the temperature is maintained for 10~14h until the high-temperature layer begins to yellow; in the middle stage, the temperature is increased at 0.8~1.2℃ / 3h to 39~41℃ (wet
bulb 35~36℃), and the temperature is maintained for 18~22h until the high-temperature layer is completely yellow and collapses; in the
late stage, the temperature is increased at 0.8~1.2℃ / 4h to 41~43℃, and the temperature is maintained for 18~22h. The color-fixing period is divided into three stages: in the early stage, the temperature is raised to 44~46℃ (wet
bulb 34~35℃) and stabilized for 3~4 hours until the main
vein of the high-temperature layer turns white; in the middle stage, the temperature is raised to 47~49℃ (wet bulb 35~36℃) and stabilized for 16~20 hours until the leaf veins of the low-temperature layer turn white and the leaves turn yellow; in the later stage, the temperature is raised to 53~55℃ (wet bulb 36~37℃) and stabilized for 18~20 hours until the leaf tissue of the low-temperature layer is completely dry. Compared with the existing curing process, this process moderately raises the temperature and
humidity during the yellowing stage and moderately reduces the
humidity and
curing time during the color-fixing stage, so that the tobacco leaves turn yellow fully, promote the rapid degradation of
starch and the transformation of
aroma components, and avoid the phenomenon of green curing,
lees curing and ash hanging on the upper tobacco leaves due to insufficient yellowing and color fixing.