Profiling of volatile and non-phenolic metabolites-Amino acids, organic acids, and sugars of green tea extracts obtained by different extraction techniques

Volatile compounds and non-phenolic metabolites (amino acids, organic acids, and sugars) of aqueous green tea extracts obtained by ultrasonic extraction (UE), agitation extraction (AE), hot water extraction (HWE), and conventional extraction (CE) were determined using SPME-GC-MS and HPLC, respectively. Significantly higher (P < 0.05) yields of volatiles and non-phenolic metabolites were obtained via UE and AE than via HWE and CE. UE, AE, HWE, and CE released 212, 201, 103, and 65 volatiles, respectively. Sum total of amino acid and organic acid in extracts was 54.57, 54.35, 27.11, and 12.67 (mg/100 g), and 5.96, 6.19, 3.81, and 1.68 (mg/100 g) for UE, AE, HWE, and CE, respectively. Volatiles except nitrogen-containing compounds had higher positive correlations with L-theanine, sucrose, malic acid, and catechins yields. Findings of the current study suggest that an efficient extraction technique may significantly increase volatile and non-phenolic metabolite yields in aqueous green tea extract.