不同成熟度烟叶烘烤中颜色值和色素含量的变化

 【目的】了解不同成熟度烟叶密集烘烤中颜色值和色素含量的变化以及它们之间的关系，为密集烘烤工艺的优化和完善提供理论依据。【方法】采用全自动测色色差计，对比研究烘烤中未熟、尚熟、适熟和过熟烟叶颜色参数（L*、a*、b*）和色差参数（△L*、△a*、△b*）的变化特征，采用分光光度法测定不同成熟度烟叶叶绿素、类胡萝卜素含量等指标。【结果】不同成熟度烟叶的L*、a*值在烘烤过程中均呈现升高的趋势，b*值在48℃之前升高，48—54℃有所下降，之后稍有回升。L*的变化规律表现为过熟>适熟>尚熟>未熟，鲜烟叶a*值在不同成熟度之间差别不大，在变黄中期之前成熟度高的烟叶a*值上升较快，烤后烟叶b*值大小表现为尚熟>未熟>过熟>适熟。随着烘烤的进行，烟叶△L*总体趋势变小。在48℃烟叶△a*明显变大，△b*相对降低，尤其以未熟和过熟烟叶明显。相关分析表明，尚熟和适熟烟叶的类胡萝卜素含量与L*值均呈极显著负相关（r = - 0.979，-0.851，P < 0.01），类胡萝卜素含量与a*值呈显著负相关（r = - 0.832，- 0.853，P < 0.05）。烘烤过程中适熟烟叶的L*、a*和b*与各种色素含量的回归方程分别为 = 245.67 x1 + 114.75 x2 - 211.69 x3 - 125.21 x4 + 118.69， = 416.9 x1 + 369.19 x2 - 404.38 x3 -78.38 x4 + 43.55，  = - 1051.55 x1 -1270.02 x2 + 1106.42 x3 + 17.48 x4 + 40.1。【结论】烘烤中不同成熟度烟叶正反面颜色变化趋势基本同步，烟叶颜色参数和色素含量的相关性明显，可以用颜色值作为辅助指标来判断烟叶成熟度。

Study on Changes of Color Parameters and Pigment Contents in Flue-cured Tobacco Leaves with Different Maturities During Bulk-curing Process

【Objective】 Changes of color parameters and pigment contents in flue-cured tobacco leaves with different maturities and their relationships during bulk curing process were studied in order to provide a theoretical basis for optimization and perfection of curing technology.【Method】Automatic color difference meter and spectrophotometer were used to study the color parameters(L*, a*, b*) and chromaticity parameters(△L*, △a*, △b*) , chlorophyll and carotenoid content of unripe, immature, ripe and overripe tobacco leaves during bulk curing process. 【Result】 During bulk curing process, both L* and a* value of flue-cured tobacco leaves of different maturities showed an ascending tendency. The b*value of flue-cured tobacco leaves with four different maturities increased before 48℃, decreased between 48℃ and 54℃, and then rose again slightly. L* value of flue-cured tobacco leaves with four different maturities showed as overripe > ripe > unripe > immature, there was little difference in a* value between four kinds of fresh tobacco leaves, among which high maturity ascended quicker, and b* of flue-cured tobacco leaves showed as immature > unripe > overripe > ripe. △L* values of flue-cured tobacco leaves with four different maturities decreased generally during bulk curing process, △a* increased obviously at 48℃ and △b* reduced, especially unripe and overripe flue-cured tobacco leaves. Correlation analysis showed that there was a significant relationship between carotenoid content and L* value in immature, ripe flue-curing tobacco leaves. Regression equation between L*, a*, b* and pigments in ripe flue-cured tobacco leaves was established during bulk curing process, (r = - 0.979, - 0.851, P < 0.05), carotenoid content was clearly negatively correlated with a* value (r = - 0.832, - 0.853, P < 0.05), which equation between L*, a*, b*and pigments in ripe flue-cured tobacco leaves was, established during bulk-curing process, which respectively were followed as:  = 245.67 x1 + 114.75 x2 - 211.69 x3 - 125.21 x4 + 118.69;  = 416.9 x1 + 369.19 x2 - 404.38 x3 - 78.38 x4 + 43.55;  = - 1051.55 x1 - 1270.02 x2 + 1106.42 x3 + 17.48 x4 + 40.1.【Conclusion】Color values of front and back of flue-cured tobacco leaves with different maturities had similar changing trend during bulk-curing process, color parameters of flue-curing showed a positive correlation with pigment contents, and color parameters could be used as an auxiliary index to judge the maturity of flue-cured tobacco.