Analysis Of Color And Related Physiological Characteristics In Cigar Leaves During Air-curing

To investigate the physiological changes such as water loss,pigment degradation,membrane lipid degradation,and ROS accumulation that occurred with color changes in cigar leaves during air-curing,the CIE-L*a*b*colorimeter was used to quantify the color of leaves.The moisture,pigment,membrane lipid,ROS content and antioxidant enzyme activities were measured.And based on the color parameters of tobacco leaves(L*,a*,b*,C*,H*,Ho),the relationships between color parameters and moisture,pigment,membrane lipid and ROS were explored.The main results showed that:(1)Changes of color in cigar leaves during air-curingThe color of cigar tobacco leaves changed from green to yellow,and finally turned to brown,the yellowing of the color started earlier than the browning.In addition,the color parameters of tobacco leaves showed the following changes:L*,b*,C*values showed a trend of increasing first and then decreasing,a*,H*values were increasing all the time,and Ho value presented a decreasing-increasing-decreasing trend.The results of simple correlation analysis showed that the color changes of the front and back in leaves were consistent.(2)Relationship between moisture loss and change of color in cigar leavesDuring the air-curing process,the moisture content and water activity of cigar leaves showed a decreasing trend.The decreasing rate of main vein water index was less than that of leaf.At the end of air-curing,the water content and water activity in the main veins were much higher than that in the leaves.Canonical correlation analysis showed that the moisture content(xl-x5)in tobacco leaves had a great influence on the a*(y2、y8)and H*(y5、yll)values of tobacco leaves.The water activity of main vein(x2)had a great influence on the L*(y1)value of the front tobacco leaf.(3)Relationship between pigment degradation and change of color in cigar leavesDuring the air-curing process,the contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoids in tobacco leaves decreased gradually,and the ratio of carotenoid to total chlorophyll increased first and then decreased.Canonical correlation analysis showed that the changes of chlorophyll a,chlorophyll b,total chlorophyll and carotenoids(x1-x4)had a great influence on the a*(y2、y8)and H*(y5、y11)values in tobacco leaves,the ratio of carotenoid to total chlorophyll(x5)had a great influence on the L*(y7)value of the back in tobacco leaves,chlorophyll b content(x2)had a great influence on the L*(y1)value of the front in tobacco leaves.(4)Relationship between membrane lipid degradation and change of color in cigar leavesThe MGDG,DGDG and PL were gradually degraded during the air-curing,and DGDG/MGDG showed a gradually increasing trend throughout the air-curing process.Data analysis results showed that MGDG(x1),DGDG(x2),and PL(x3)had a great impact on the a*(y2、y8)and H*(y5、y11)values in the tobacco leaf.In addition,the PL content(x3)had a great impact on the L*(y1,y7)value.(5)Relationship between ROS accumulation and change of color in cigar leavesThe production rate of O2-,H2O2 and MDAcontent showed a gradually increasing trend during the air-curing process,and the activity of antioxidant enzymes also changed accordingly.The activities of SOD and POD increased first and then decreased while the content of APX decreased all the time during air-curing.Data analysis showed that O2-production rate(x1),H2O2(x2)and MDA content(x3)had great effects on a*(y2、y8),C*(y4、y10)and H*(y5、y11)values of tobacco leaves.SOD activity(x4)and POD activity(x5)had a great impact on the L*(yl,y7)value.And the results showed that MDA content(x3)and SOD activity(x4)had a great influence on the Ho(y6、y 12)and b*(y3)values in tobacco leaves,...