Abstract:
Five flue-cured tobacco varieties, Yunyan 87, Yueyan No. 1, HB030, Xiangyan No. 7, and NX212, were used to simulate the color fading test of cured tobacco leaves. The color difference and variation regularities of the main chemical components of cured leaves before and after their color fading were investigated, and an OPLS model was established to analyze the relationships between the main chemical components and color fading. The results showed that: 1) After color fading, the redness value
a* and yellow value
b* of the leaves decreased, the brightness value
L* increased, and the total color difference value decreased. Meanwhile, the mass fractions of total sugar, total nitrogen, total phenol, chlorogenic acid, rutin and carotenoid decreased, while the mass fractions of reducing sugar, nicotine, oxalic acid, malic acid, citric acid and total organic acids increased. 2) The analysis results of OPLS model showed that
L*,
a* and
b* indexes were positively correlated with total sugar, total nitrogen, carotenoid, chlorogenic acid and rutin, and negatively correlated with reducing sugar, nicotine, oxalic acid, malic acid and citric acid. 3) Among all the tested varieties, the total color difference value, polyphenols and carotenoids decreased less after color fading of NX212, and its color fading degree was the least, as this leaf type belonged to the color fading resistant varieties.