Effects of Pre-harvest Induction and Post-harvest Processing of Tea Leaves on Carotenoids and Their Derived Aromas

Carotenoids are important lipid -soluble pigments in tea plants, which contributes to various key aromas as precursors. In this study, targeted metabolomics was applied to qualitative absolute content of carotenoids in tea leaves, and it was clear that the total content was (859.98±60.20) μg/g, which lutein contributed the highest ones as (405.06± 17.71) μg/g. In made black and green tea, which manufactured by traditional black tea and green tea processing respectively, absolute content of carotenoids remained nearly half inside which decreased more than 50% compared with fresh leaves [(406.17±32.21) μ/g and (433.95±36.21) μ/g respectively]. Interestingly, spraying exogenous methyl jasmonate solution (0.25%) on tea leaves will greatly impact on the constituents of carotenoids. Especially in made green tea which was prepared from tea leaves treated with methyl jasmonate (12 h), carotenoids greatly remained in made tea as high content of (682.69±46.12) μ/g, however, decreased in made black tea [(433.95±36.21) μ/g]. Fourteen carotenoid—derived aroma components were identified with significantly increase in black tea and green tea prepared from fresh leaves induced by methyl jasmoante for 24 h, especially the relative contents of j3—damascenone, j3—ionone, geranyl acetone and dihydroactinidiolide increased >2 times. Our results ensured acknowledge of carotenoids constituent and content in tea, promised a clear vision of carotenoids dynamics before, during, and after tea processing. It was confirmed that aroma quality of made teas (green tea and black tea) were greatly improved especially after 12 h and 24 h MeJA treatment time duration, and furthermore maintained a higher content of carotenoids. In conclusion, this study unraveled the mechanism of carotenoids content improvement in tea treated by methyl jasmonate. This will greatly improve our knowledge on taking advantage of exogenous application in tea quality improving. © 2023 Chinese Institute of Food Science and Technology. All rights reserved.