Effects of Harvest Maturity on Color Change of Cigar Tobacco Leaves During Air-curing

To explore the influence of maturity of cigar tobacco leaves on color change during air-curing, the middle leaves QX103 were used to study the effects of different maturity (M1, M2, M3) on color characterization index, plastid pigment content, water content, malondialdehyde (MDA) content, polyphenol oxidase (PPO) activity and polyphenol content during air-curing. The results showed that during the air-curing process, the yellowing rate of cigar tobacco leaves was M3>M2>M1, and the browning rate was M2>M3>M1. After air-curing, M2 leaves were darker in brown; the chlorophyll a and b of each treatment were greatly degraded, and the degradation range was M3>M2>M1. The water loss range was M2>M3>M1. The MDA content in leaves of each treatment showed an upward trend within 10 days of drying, and the content on the 10th day was M2>M3>M1. The PPO activity of different maturity tobacco leaves increased during 0-10 days of air-curing, and the activity was M2>M3>M1 on the 10th day and the differences among the treatments were significant. PPO activity decreased during the 10-15 days, and M2 leaves decreased the most. During air-curing chlorogenic acid, rutin and scopoletin in the M1 treatment were less oxidized, and finally the phenolic content accumulated more. In summary, the degree of water loss and membrane lipid peroxidation of cigar tobacco leaves with different harvest maturity during air-curing was different, which made the rate of pigment degradation and polyphenol oxidation of tobacco leaves different, and further affected the color change process of cigar tobacco leaves and the color depth of tobacco leaves after air-curing.