变色期晾制温度对雪茄烟叶氮素转化机理的影响

为探究变色期不同晾制温度对雪茄烟叶氮素转化机制的影响，以川雪1号为试验材料，设置4个温度处理(23℃、25℃、27℃和29℃)，测定分析不同处理下的烟叶主要含氮化合物含量及相关酶活性。结果表明，随着变色期晾制温度的增加，烟叶内部硝酸还原酶和亚硝酸还原酶活性呈先升后降的趋势，23℃与29℃温度处理的烟叶酶活性显著降低。随着变色期晾制温度的增加，各处理的硝酸盐和亚硝酸盐含量呈先降后升的趋势，氨和总挥发碱含量显著降低，蛋白质含量显著升高，其中温度为27℃处理的烟叶内NH₄⁺-N和氨基酸含量显著升高，亚硝酸盐含量显著降低。烟叶内氨转化产物的相关性分析表明，各处理烟叶中的氨与总挥发碱、总氮和蛋白质含量整体呈显著负相关，与NH₄⁺-N和氨基酸含量相关性不显著。当变色期温度控制在27℃时，烟叶内化学成分较协调，烟叶物理特性和感官质量最好，25℃处理次之。综上所述，变色期适宜的晾制温度条件有利于雪茄烟叶品质的提高。

Effects of Drying Temperature on Nitrogen Transformation Mechanism of Cigar Tobacco during Discoloration Period

In order to explore the effects of drying temperature conditions on the nitrogen transformation mechanism of cigar tobacco leaves during discoloration period, taking Chuanxue No.1 as the test material, four temperature treatments（23°C, 25°C, 27°C and 29°C）were set, and the contents of main nitrogen compounds and the activities of key enzymes for nitrogen conversion in tobacco leaves were determined and analyzed. The results showed that, the activities of nitrate reductase and nitrite reductase in tobacco leaves increased first and then decreased with the increase of drying temperature during discoloration period. The enzyme activities of tobacco leaves treated at 23°C and 29°C were significantly decreased. With the increase of the drying temperature, the contents of nitrate and nitrite in each treatment showed a trend of first decreasing and then increasing, the contents of ammonia and total volatile alkali decreased significantly, and the protein content increased significantly, the contents of NH₄⁺-N and amino acids in tobacco leaves treated at 27°C were significantly increased, and the content of nitrite was significantly decreased. The correlation analysis of ammonia conversion products in tobacco leaves showed that the ammonia content of each treatment had a significant negative correlation with total volatile alkali, total nitrogen and protein while having no significant correlation with NH₄⁺-N and amino acid content. When the temperature in discoloration period was controlled at 27°C, the chemical components in tobacco leaves were more coordinated, and the physical properties and sensory quality of tobacco leaves were the best, and the treatment with 25°C took the second place. To sum up, suitable drying temperature conditions during discoloration period are beneficial to improve the quality of cigar tobacco leaves.