Effect of Soaking Time and Steeping Temperature on Biochemical Properties and γ-Aminobutyric Acid (GABA) Content of Germinated Wheat and Barley

Abstract

The objective of this research was to investigate the effects of soaking time (6, 12 and 24 hr) and steeping temperature (25, 30 and 35℃) on germination time, germination percentage and weight loss of wheat and barley. Changes in chemical composition (such as protein, fat, and ash), reducing sugar content, enzyme activity and pasting profile and GABA (γ-animobutyric acid) content of germinated wheat and barley were also evaluated. The results clearly suggest that the short soaking time and lower steeping temperature significantly decreased germination time and weight loss, while germination percentage increased. Regarding the chemical composition, the protein content of wheat and barley was slightly increased after germination but there was no significant difference in content of crude fat and ash of both germinated cereals. The reducing sugar content of both germinated cereals decreased as the steeping temperature increased from 25℃ to 35℃. Increasing soaking time and steeping temperature led to increased amylase activity, and also corresponded to reduced paste viscosity. The highest GABA content that occurred with soaking times of 6 and 12 hr and a steeping temperature of 35℃ was 1,467.74 and 1,474.70 ㎍/g for germinated wheat and 2,108.13 and 1,691.85 ㎍/g for germinated barley. This study indicated that the optimum germination process for wheat and barley is a low steeping temperature and a short soaking time.