变黄期阶梯升温烘烤工艺对多酚类及相关物质的影响

摘要

采用电热式温湿度自控密集烤烟箱,研究了变黄期阶梯升温烘烤工艺对多酚类物质、相关酶活性及含氮化合物的影响.结果表明,密集烘烤过程中,各烘烤工艺的总酚、绿原酸、咖啡酸和芸香苷含量总体上均呈上升趋势.除烘烤变筋期,变黄期阶梯升温烘烤工艺的总酚和绿原酸含量高于对照.咖啡酸、芸香苷、莨菪亭等含量在烘烤过程中变化各不相同,烘烤结束两工艺差异较小.棕色化反应的敏感期,变黄期阶梯升温烘烤工艺的多酚氧化酶(PPO)活性较低;烘烤期间,该工艺的过氧化物酶(POD)活性明显高于对照.烘烤过程中,变黄期阶梯升温烘烤工艺的苯丙氨酸和酪氨酸均表现出"降-升-降"的趋势;烘烤中后期,变黄期阶梯升温烘烤工艺的蛋白质降解得较低,而两种氨酸含量则较高.总之,变黄期阶梯升温烘烤工艺有利于烤后烟叶总酚、绿原酸含量和芳香值的提高,利于蛋白质的降解及苯丙氨酸和酪氨酸的积累.%Effects of the step-temperature yellowing curing technology on polyphenol, related enzyme activities and nitrogen compounds in tobacco leaves were studied using electric-heated flue-curing barn. The results showed that contents of total phenols, chlorogenic acid, caffeic acid and rutin increased during all bulk curing processes. Total phenols and chlorogenic acid contents of the step-temperature yellowing technology were higher than control except at the muscle-yellowing temperature stage. The contents of caffeic acid, rutin and scopoletin changed differently between the two technologies, but little difference was detected at the end of curing. Lower Polyphenol oxidase(PPO)activity during the sensitive period of the brown reaction and significantly higher Peroxidase(POD) activity during curing were observed for the step-temperature yellowing technology. With the step-temperature yellowing technology, the changes of phenylalanine and tyrosine of the showed a down-up-down trend during curing, lower proteins content and higher phenylalanine and tyrosine contents in middle and late curing period were observed. In short, the step-temperature yellowing technology was beneficial in improving the contents of total phenols, chlorogenic acid and aroma values, and was also favorable to protein decomposition and accumulation of phenylalanine and tyrosine.