Analysis of Volatile Substances in Sun-dried Green Tea in Menghai County Based on Electronic Nose and SPME/GC-MS Technology

In order to understand the volatile matter information of sun-dried green tea in Menghai County, eight samples of sun-dried green tea in Menghai County were detected by electronic nose and headspace solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The results of electronic nose detection showed that the 8 tea samples could be divided into 4 groups, among which 5 tea samples from Nannuoshan (NN), Xiding (XD), Bulangshan (BL), Gelanghe (GL) and Zhangjiasandui (ZJ) belonged to one group, while Bada (BD), Bulangshan Border (BJ) and Bada Zhanglang (ZL) belonged to one group respectively. Sulfides and hydrocarbons were the main volatile compounds in the sun-dried green tea samples enriched by electronic nose. GC-MS results showed that 55 volatile compounds were detected in 8 sun-dried green tea samples, mainly alcohols (9 kinds), esters (7 kinds), aldehydes (9 kinds), ketones (6 kinds), alkenes (13 kinds), alkanes (5 kinds), heterocyclic (4 kinds). Alcohols had the greatest influence on the relative content of volatile substances in sun-dried green tea, the highest was ZL tea sample (64.02%), and the lowest was BJ tea sample (37.14%), which was mainly manifested in linalool and phytol. There were 19 kinds of volatile substances in 8 sun-dried green tea samples, and 10 kinds of higher content were 3 alcohols (linalool, α-terpineol, geraniol), 2 aldehydes (phenylacetaldehyde, crocinaldehyde), 2 ketones (β-ionone, phytoketone), 2 heterocyclic compounds (cis-linalool oxide, trans-linalool oxide), 1 esters (dihydroactinidiolide). The total relative content of volatile substances in sun-dried green tea in Gelanghe township was higher than that in Nannuoshan township and Xiding township, mainly in aldehydes. The dominant aroma components of sun-dried green tea in Bulangshan township were ketones and alkanes; The dominant aroma components in Xiding township were olefins, that was, sun-dried green tea from different producing areas had different dominant volatile substances.