Analysis of Flavor Quality of ‘Chungui’ Minbei Oolong Tea with Different Baking Degrees

Sensory evaluation, biochemical analysis, ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS) and headspace solid-phase microextraction combined with gas chromatography-time-of-flight mass spectrometry (HS-SPME-GC-TOF-MS) were used to detect and analyze different baking degrees of ‘Chungui’ Minbei oolong tea. Partial least squares discriminant analysis model and trend model were established to explore the differences in sensory quality, conventional biochemical components, catechin components, amino acid components and volatile substances. The results showed that the total score of sensory evaluation of light baking degree of ‘Chungui’ (91.3~93.65) was slightly lower than that of medium baking degree (93.6~94.15). Among the biochemical components, the amino acid content of light baking degree was significantly higher than that of medium baking degree (P<0.05), and the content of theaflavin, theabrownin and the ratio of phenol to ammonia in medium baking degree were significantly higher than those in light (P<0.05). The TAV values of amino acid components were calculated, and the main amino acids contributing to the taste of light baking degree of ‘Chungui’ were cysteine, aspartic acid, glutamic acid and theanine, while those of medium baking degree were cysteine, glutamic acid and theanine. Among the main differential volatile substances, the contents of volatile substances such as nerolidol, indole, α-farnesene and cis-jasmone in the light baking degree of ‘Chungui’ were significantly higher than those in the medium baking degree (P<0.05). The contents of cis-linalool oxide, tea pyrrole, 2,5-dimethyl pyrazine, furfural, dehydro-β-ionone and dihydroactinidiolide in the medium baking degree of ‘Chungui’ were significantly higher than those in the light baking degree of ‘Chungui’ (P<0.05). ‘Chungui’ Minbei oolong tea was suitable for medium fire baking process. Its taste was mellow, strong and floral, and the aroma type was floral fragrance, and the comprehensive quality was better. This study would provide a theoretical basis for the supporting processing technology and flavor quality of ‘Chungui’ Minbei oolong tea.