密集烘烤定色期升温速度对烤烟类胡萝卜素降解和颜色的影响

Study on carotenoids degradation and color changes of flue-cured tobacco at leaf-drying stage during bulk curing

采用河南农业大学设计的电热式温湿自控密集烤烟箱,研究了密集烘烤定色期不同升温速度对烤烟类胡萝卜素降解组分、降解香气成分含量及颜色的影响.结果表明,类胡萝卜素含量随烘烤时间的推进逐渐降低,β-胡萝卜素、叶黄质、新黄质和紫黄质在定色期的降解幅度均为:慢速升温(1℃/2.0 h)>中速升温(1℃/1.5 h)>快速升温(1℃/1.0 h),慢速升温处理类胡萝卜素总量降幅达76.11%.烤后烟叶类胡萝卜素降解香气物质含量以慢速升温处理最高(39.73μg·g-1),其次为中速升温处理(35.07μg·g-1).烟叶各颜色参数在定色期开始后的18 h前后均有一个高峰,定色过程中亮度(L*)、红度值(a*)与烟叶类胡萝卜素及其各组分含量均呈负相关,其中a*与类胡萝卜素组分含量的相关性较好.可见,定色期以1℃/2.0 h升温利于烟叶类胡萝卜素的充分降解和外观质量及香气质量的改善.

In order to improve the aroma quality of flue-cured tobacco and provide a theoretical basis for the optimization of curing technology, effects of the temperature-increasing rate at the leaf-drying stage during bulk-curing on the carotenoid degradation, content of the aroma components produced by carotenoid degradation and color change of tobacco leaves were studied. Results showed that： carotenoid content decreased gradually at the leaf-drying stage; the degradation degrees of β-carotene, lutein, neoxanthin and violaxthin were an in order： slow heating rate （ T3 ） 〉 medium heating rate （ T2 ） 〉 high heating rate （ T^＊ ） ; the carotenoid degradation rate of T^＊ was the highest, i.e. 76.11%. Content of the aroma components of T3 was the highest, reaching 39.73 μg·g^-1, next was the T2, i.e. 35.07 μg·g^-1. The color parameters reached their peaks 18 h after the starting of leaf-drying stage. There were negative correlations between the color parameters of tobacco L^ ＊ , a^ ＊ and the contents of carotenoids as well as the other components, and there was a good correlation between a^＊ and carotenoids contents. In general, heating rate of 1 ℃/2.0 h would benefit the sufficient degradation of carotenoids and improve the aroma and appearance quality of tobacco leaves at leaf-drying stage.