Effect of Different Processing Technologies on the Key Aroma-Active Compounds of Green Tea

Green tea was made from one bud with two leaves from the tea cultivar Longjing 43 by stir frying, roasting, steaming or sun drying. Stir bar sorptive extraction (SBSE) combined with gas chromatography-olfactometry-mass spectrometry (GC-O-MS) was applied to analyze the influence of different manufacturing processes on the key aromaactive compounds of green tea. The results showed that 31, 27, 25 and 30 key aroma-active compounds were respectively identified from stir-fried green tea, roasted green tea, steamed green tea and sun-dried green tea, which all had floral, fruity and green flavors. Totally, 13 key aroma-active compounds were common to these 4 types of green tea, including β-ionone, naphthalene, linalool, linalool oxide I, geraniol, 1-octene-3-ol, 2-heptanone, heptanal, hexanal, (Z)-3-hexenyl acetate, (E,E)-2,4-decadienal, α-ionone, and phenylethyl alcohol. It was found that β-ocimene and (Z)-hex-3-enyl 2-methylbutyrate contributed greatly to the aroma characteristics of stir-fried green tea; 2-pentylfuran, phenylacetaldehyde and α-terpineol contributed greatly to the aroma characteristics of roasted green tea; and geranylacetone, γ-terpinene and α-citral contributed greatly to the aroma characteristics of sun-dried green tea. The results obtained from this study will help to understand the formation mechanism of green tea aroma quality and to develop directional processing and regulation technologies for green tea aroma quality.