Quality analysis and identification of Zijin Cicada tea fresh leaves with different biting degrees based on E-nose and HS-SPME-GC-MS
The identification of biting degree of Zijin Cicada tea fresh leaves is a key step in the production,which relies on manual assessment of the honey fragrance intensity in fresh leaves currently.However,this method suffers from the drawback of low production efficiency.In this study,fresh leaves with different biting degrees were collected to determine the physicochemical parameters,and the volatile components were detected by E-nose and high-performance headspace gas chromatography-mass spectrometry(HS-SPME-GC-MS).The results showed that:the tea polyphenols,catechins and soluble sugars increased initially and then decreased with the increase of biting de-gree,and the concentrations reached peak values at moderate biting degree;the amino acid content exhibited a posi-tive correlation with the biting degree,showing the maximum increase of 0.27％,while the caffeine content had a neg-ative correlation,with the maximum reduction of 0.90％.These changes mainly reflected the tea's response to insect infestation,consequently impacting the overall taste of the tea.HS-SPME-GC-MS results indicated significant differences in the aroma compounds of tea with different biting degrees,including ethyl 3-Phenylpropionate and Methyl cyclopentylacetate,which contributed to honey aromas.The partial least squares regression(PLSR)analysis revealed the intrinsic relationship between the electronic nose sensor response and the aroma substances detected by HS-SPME-GC-MS.The model of E-nose data after dimensionality reduction by support vector machine identified tea with different biting degrees.The results of the study enable the qualitative analysis of characteristic tea aromas and provide a novel approach for identifying the biting degree of Zijin Cicada tea.
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