Seed protein, soaking duration and soaking temperature effects on gamma-aminobutyric acid concentration in short-season soybean.

Morrison, M.J., Frégeau-Reid, J.A., and Cober, E.R. (2013). "Seed protein, soaking duration and soaking temperature effects on gamma-aminobutyric acid concentration in short-season soybean.", Crop Science, 53(6), pp. 2563-2568. doi : 10.2135/cropsci2013.02.0088  Access to full text

Abstract

Gamma aminobutyric acid (GABA) is a four-carbon, nonprotein amino acid found in soybean [Glycine max (L.) Merr.] seed and food. The consumption of foods with high GABA concentration may be an alternative to pharmaceutical medication for hypertension, an affliction affecting one billion people. The objectives of this study were to examine the relationship between GABA and protein concentration in high, medium, and low protein soybean cultivars and to determine the relationship between soaking temperature (T) (21 or 27°C) and duration (0, 3, 6, 18, and 24 h) on L-glutamate (L-Glu) and GABA concentration. The high-protein cultivar did not have significantly higher L-Glu or GABA concentration than the medium or normal protein cultivars. Seed L-Glu increased rapidly with soaking duration up to 8.25 h, and the 27°C soaking T resulted in higher concentrations than the 21°C T. Seed GABA concentration increased rapidly with soaking duration and peaked at 10 and 12 h for the low- and high-GABA cultivars, respectively. The cultivar with the highest concentration of stored L-Glu and GABA remained the highest after soaking. Increasing soaking duration and temperature can be used to increase the seed GABA concentration in cultivars, although this may increase processing time.

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