Process Optimization and Quality Components Analysis of γ-Aminobutyric Acid Pickled Tea.

Pickled tea is an anaerobically fermented tea common in Thailand, Myanmar and Yunnan minority areas. γ-aminobutyric acid (GABA) is non-protein amino acid with multiple bioactives, which can be easily produced under anaerobic conditions. During the processing of pickled tea, controlling the process parameters is effective for the production of GABA-rich products; however, the precise parameters remain to be clarified. In the present study, the fresh leaves of (L.) Kuntze () 'FudingDabai', 'MabianLv No. 1', 'Wuniuzao' and 'Fuxuan No. 9' were used as raw materials to process GABA-rich pickled tea. Single-factor and orthogonal experiments were conducted to determine the best tea cultivars and optimize the best processing parameters via comparing the content of GABA, tea polyphenols (TPs) and other biochemical components of GABA-rich pickled tea. The results of the signal-factor experiment showed that the fresh leaves of 'MabianLv No. 1' had the highest GABA content of 2.61 mg·g after treatment with vacuum for 6 h; therefore, 'MabianLv No. 1' was selected as the raw material for the subsequent experiments. Orthogonal experiments showed that the highest GABA content of 2.53 mg·g was found in the pickled tea with 8 h of vacuum treatment, 20 min of rolling after microwave fixing, 20 min of spreading and 20 d of anaerobic fermentation at room temperature. Further, the sensory evaluation showed that it possesses a strong sour taste with a slight sweetness and a light yellow color and better comprehensive quality. This indicates that these parameters are optimal for the processing of GABA-rich pickled tea. This study will provide scientific basis for the subsequent production of high GABA tea.