Aroma changes of black tea prepared from methyl jasmonate treated tea plants

Abstract

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 MeJAtreated black tea was clearly improved.

Identification of key aromatic compounds in Congou black tea by partial least‐square regression with variable importance of projection scores and gas chromatography–mass spectrometry/gas chromatography–olfactometry

“…4‐Hydroxy‐2,5‐dimethyl‐3(2 H )‐furanone had a significant influence on the ‘sweet’ aroma, followed by ( E )‐2‐hexenal, dodecanal, β ‐myrcene, α ‐farnesene, and nerolidol. 1‐Octen‐3‐ol, which contributed significantly to the ‘woody and mushroom‐like’ smell, had the highest negative coefficient (−1.76) . Methyl jasmonate, which has a ‘floral’ smell, is well known, as it could improve the aroma quality of agricultural products such as tea, fruits, and vegetables .…”

“…Among the three major kinds of tea (black, green, and oolong), black tea accounts for approximately 75% of the world's tea trade . Congou black tea, which originated in China, is the oldest black tea in the world and has been well known for centuries, such as Keemun black tea and Dianhong black tea . By using the orthodox method, which includes withering, rolling, fermentation, and firing, Congou black tea has a more complete shape and a lower degree of oxidation of phenolic compounds.…”

Characterization of aromas of instant oolong tea and its counterparts treated with two crude enzymes from Aspergillus niger

“…Therefore, it is reasonable to draw a conclusion that the content changes of the volatile constituents were resulted from the enzymatic treatment. It has been reported that geraniol could be generated via the catalysis of geraniol synthase and β‐glucosidase (Ho, Zheng, & Li, ; Su, Xia, Gao, Dai, & Zhang, ); benzaldehyde might come from the oxidative degradation of amino acids (Ho et al, ); phenylethyl alcohol could be generated by the enzymatic hydrolysis of its glycoside precursors (Shi et al, ); and β‐ trans‐ damascenone might result from the transformation of glycoconjugate precursors at high temperatures during the manufacturing of tea leaves (Kinoshita et al, ). In addition, the contents of benzaldehyde and phenylethyl alcohol have been observed to increase after the combined treatment of laccase and α‐galactosidase (Zhang & Du, ).…”

Analysis of Young Shoots of ‘Anji Baicha’ (Camellia sinensis) at Three Developmental Stages Using Nontargeted LC‐MS‐Based Metabolomics

“…Jasmonates influence the coordinated expression of numerous genes encoding key enzymes in plant secondary metabolic pathways, thus affecting the accumulation of plant secondary metabolites at the transcription level (Vom Endt, Soares e Silva, Kijne, Pasquali, & Memelink, ). MeJA has also been reported to improve the aroma quality of black tea clearly (Shi et al., ). When plants are subjected to low‐temperature stress, a series of physiological and biochemical changes occur accompanied by increasing levels of jasmonates.…”