Aroma changes of black tea prepared from methyl jasmonate treated tea plants.
Methyl jasmonate (MeJA) was widely applied in promoting food quality. Aroma is one of the key indicators in judging the quality of tea. This study examined the effect of exogenous MeJA treatment on tea aroma. The aroma components in black tea prepared from MeJA-treated fresh tea leaves were extracted using headspace solid-phase microextraction (HS-SPME) and were analyzed using gas chromatography-mass spectrometry (GC-MS) and GC-olfactometry (GC-O). Forty-five volatile compounds were identified. The results revealed that the MeJA-treated black tea had higher levels of terpene alcohols and hexenyl esters than the untreated tea. Moreover, several newly components, including copaene, cubenol, and indole, were induced by the MeJA treatment. The activities of polyphenol oxidase and β-glucosidase in fresh tea leaves changed after the MeJA treatment. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the gene expression levels of polyphenol oxidase and β-primeverosidase were upregulated by two and three folds, respectively, by the MeJA treatment (P<0.01); however, the gene expression of β-glucosidase was downregulated to a half level. In general, the aroma quality of the MeJA-treated black tea was clearly improved.
Key Laboratory of Tea Biology and Resource Utilization of Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China; Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China; Lin'an Agriculture Bureau, Lin'an 311300, China.
Jiang
J
Shi
Li
L
Wang
Cheng-ying
CY
Ma
Hai-peng
HP
Lv
Zong-mao
ZM
Chen
Zhi
Z
Lin
D000085:Acetates / Q000494:pharmacology*; D028241:Camellia sinensis / Q000737:chemistry* / Q000187:drug effects* / Q000378:metabolism; D004156:Catechol Oxidase / Q000235:genetics / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology*; D063427:Food Quality; D008401:Gas Chromatography-Mass Spectrometry; D015870:Gene Expression / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009812:Odorants / Q000032:analysis*; D054883:Oxylipins / Q000494:pharmacology*; D052617:Solid Phase Microextraction; D013662:Tea / Q000737:chemistry*; D055549:Volatile Organic Compounds / Q000032:analysis; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism
D000085:Acetates; D003517:Cyclopentanes; D054883:Oxylipins; D013662:Tea; D055549:Volatile Organic Compounds; C072239:methyl jasmonate; D004156:Catechol Oxidase; D006026:Glycoside Hydrolases; C460087:beta-primeverosidase; D001617:beta-Glucosidase