Abstract:To investigate the dynamic changes in the aroma components of Rucheng Baimao (Camellia pubescens) black tea, gas chromatography-mass spectrometry (GC-MS) technology was used to detect the volatile components in fresh tea leaves, withered tea, rolled tea, fermented tea, and dried tea. The results showed that a total of 129 volatile components were detected, which could be divided into alcohols, aldehydes, esters, ketones, alkanes, alkenes, and other seven categories. Among them, alcohols accounted for 23.26% (30 types), esters accounted for 27.13% (35 types), and alkanes accounted for 23.26% (30 types), which were the main categories of volatile components in the processing process. The five volatile components with rOAV>1 in the dry tea, linalool, phenethyl alcohol, geraniol, 2-phenylethanal, and β-ionone, are important contributors to the aroma quality of Rucheng Baimao (Camellia pubescens) black tea. The relative contents of linalool, phenethyl alcohol, geraniol, 2-phenylethanal, and β-ionone all increased first and then decreased during the processing process. Linalool reached the highest content (154.80 μg/kg) during the withering stage, whilst geraniol, 2-phenylethanal, and β-ionone had the highest levels during the fermentation stage (28.41, 10.75 and 4.09 μg/kg, respectively). The relative content of phenethyl alcohol showed a fluctuating trend during the processing process, and reached the highest value (10.66 μg/kg) during the fermentation stage. The metabolic pathways these five volatile components were involved were mainly the MVA and MEP pathways, the phenylalanine metabolism pathway, and the carotenoid degradation pathway for volatile terpenoids biosynthesis. The results of this study can provide a theoretical reference basis for the regulation of aroma quality of Rucheng Baimao (Camellia pubescens) black tea.
