Characterization of the aroma profiles of oolong tea made from three tea cultivars by both GC-MS and GC-IMS

Abstract

Tea cultivar is crucial for oolong tea aroma quality. However, the aroma characteristics of oolong tea made from different cultivars have rarely been studied. The aroma profiles of fresh tea leaves and oolong teas derived from Shuixian (SX), Huangmeigui (HMG) and Zimudan (ZMD) cultivars were comprehensively analyzed by gas chromatography-mass spectrometry, gas chromatography-ion mobility spectrometry (GC-IMS), sensory evaluation and odor activity value (OAV) determination. 12 volatiles (OAV＞1) contributed to the overall aroma, of which benzeneacetaldehyde (OAV 2.14) and 3,5-diethyl-2-methylpyrazine (OAV 1.25) were the aroma-active compounds for HMG tea. Significantly more volatiles and stronger floral odor were from HMG and ZMD than the SX tea. Moreover, popcorn-like, creamy odors with high-intensity, and caramel-like odor were only recorded in HMG and ZMD samples. Additionally, 27 volatiles were identified by GC-IMS only, indicating the benefits of combined method for a better understanding of the impact of cultivars on tea aroma profiles.

Keywords: Aroma profiles; Gas Chromatography-Ion Mobility Spectrometry (GC-IMS); Gas Chromatography-Mass Spectrometry (GC–MS); Odor activity value (OAV); Oolong tea; Tea cultivar.