Study On The Effect Of Exogenous Methyl Jasmonate On Tea Aroma

Aroma, one of the key indicators of tea quality, is influenced by tea cultivars, prevailing climatic conditions, cultivation practices, processing technologies and other extraneous factors. The paper conducted the study on the effect of exogenous methyl jasmonate (MeJA) treatment on tea aroma.The aroma components in fresh tea leaves treated by MeJA and processed tea made of them were extracted by headspace solid-phase micro-extraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). Moreover, the characteristic aroma components of the made tea were further identified by GC-O. After clarifying the variation of tea aroma induced by the exogenous MeJA, this study could provide a theoretical basis and technical support for using exogenous inducer to enhance the aroma quality and develop a new flavor tea. The main research results were as follows:1. The relative content of terpenes and hexenyl esters in fresh tea leaves treated by MeJA were increased and showed a regular variation. The relative content of major terpenes and hexenyl esters were increased and reached a peak in 24 hour after the induction. The effective concentration of MeJA was 0.10%~0.50%, especially 0.25% and 0.50%.2. The relative content of terpenes and hexenyl esters in made teas which were made of fresh leaves treated by MeJA were increased and showed a similar variation tendency like in the fresh tea leaves. The aroma sensory quality of made teas, especially green tea and oolong tea, were also improved. The terpenes, hexenyl esters in made teas induced by MeJA were found to have a certain aroma sniffing activity by GC-O. This may be main reasons for the increase of made tea's aroma.3.α-Cubebene,β-Cubebene, caryophyllene,α-Farnesene,δ-Cadinene and other terpenes, (Z)-3-hexenyl butyrate,(Z)-3-hexenyl isovalerate,(Z)-3-hexenyl hexanoate,(E)-3-hexenyl hexanoate, (Z)-3- hexenyl benzoate and other hexenyl esters were obviously varied both in the fresh tea leaves and made teas treated by exogenous MeJA.β-Cadinene, Copaene, Cubenol and Indole were new aroma components induced by MeJA.