Determination of γ-Aminobutyric Acid and Free Amino Acid Contents in Barley Seeds and Amounts Produced by Water Soaking Treatment

Abstract

The contents of γ-aminobutyric acid (GABA) and free amino acid in barley seeds, and the amounts produced by water soaking treatment, were determined. In decreasing order among wholemeal, Kankei n553, Kankei n554, Hiproly, Yonkei 9551, and Beau Fiber contained GABA at 41.7, 27.1, 24.5, 21.9, and 19.3 mg/100 g, respectively, and all had high lysine (lys) endosperm mutations. Yonkei 9551 (25.6 mg/100 g) with high lys gene lys1 and Yonkei 9552 (11.1 mg/100 g) with high lys gene lys3.a contained relatively large amounts of GABA in 60% flour. Barleys having high lys gene lys3.a contained a large amount of total free amino acid (338.2 − 626.2 mg/100 g) in wholemeal. The amino acids predominantly produced from the wholemeal of barley seeds generally matched those from wheat.