Abstract: Orthogonal array design was used to optimize conditions for the fermentation and germination of brown rice for separate use for the production rice tea. The results show that both fermentation and germination were conducive to increasing the contents of free amino acids, reducing sugar and γ-aminobutyric acid (GABA) in rice tea, improving its quality. The optimal fermentation conditions were fermented rice (resulting from 24 h natural fermentation of rice and water) : pineapple juice (1:1.5, V/V) as fermentation starter, 35 ℃ of fermentation temperature and 18 h of fermentation time. The rice tea obtained had maximum free amino acid content, a strong aroma, a genuine taste of rice and a clear orange colour. The optimal germination conditions were calcium lactate at 0.5 mmol/L as glutamate decarboxylase activator, pH 5.5–6, 35 ℃ of germination temperature and 24 h of germination time. The resulting rice tea had maximum contents of reducing sugar and GABA, a clear colour and a lingering aftertaste.

Key words: brown rice, rice tea, fermentation, germination, process conditions