Dynamic Changes in γ-Aminobutyric Acid and Glutamate Decarboxylase Activity in Oats (Avena nuda L.) during Steeping and Germination

gamma-Aminobutyric acid (GABA) is the principal inhibitory neurotransmitter in the central nervous system and provides beneficial effects for human and other animals health. To accumulate GABA, samples from two different naked oat cultivars, Baiyan II and Bayou I, were steeped and germinated in an incubator. The content of GABA and glutamic acid as well as the activity of the glutamate decarboxylase (GAD) in oats during steeping and germination were investigated with an amino acid automatic analyzer. Compared with raw groats, an increase in GABA content of oat groats during steeping and germination was continuously observed for two oat cultivars. The activity of GAD increased greatly at the end of steeping and the second stage of germination for Baiyan II and Bayou I, respectively. Glutamic acid content of treated oat groats was significantly lower than that in raw groats until the later period of germination. GABA was correlated (p < 0.01) significantly and positively with the glutamic acid rather than GAD activity in the current study. The results indicates that steeping and germination process under highly controlled conditions can effectively accumulate the GABA in oat groats for Baiyan II and Bayou I, which would greatly facilitate production of nutraceuticals or food ingredients that enable consumers to gain greater access to the health benefits of oats. However, more assays need to be further performed with more oat cultivars.