Changes of volatile compounds and odor profiles in Wuyi rock tea during processing

Wuyi rock tea (WRT), is one kind of oolong tea and widely appreciated for its typical ‘rock flavor’. The odor characteristics of WRT during processing were comprehensive investigated by gas chromatography-mass spectrometry, sensory evaluation and odor activity value (OAV). Alcohols, alkenes and esters were the main volatiles formed during tea processes, but the WRT contained more heterocyclic compounds, among which 15 N-containing volatiles were newly identified in this study, accounting for 60.52% of total amounts of volatiles in WRT. In response, the original green and chemical odors converted to roasted and woody odors, and full fire processing was effective to enhance roasted, floral and woody odors, weaken chemical odor. 2-Ethyl-3,5-dimethylpyrazine (OAV 4.71) was confirmed as the aroma-active compound of WRT with roasted odor by aroma recombination experiment. In addition, strong roasted, floral and moderate woody odors were perceived as the outline of ‘rock flavor’ in WRT aroma. These results provide theoretical basis for processing and quality control of WRT.