Acta Scientiarum Polonorum Technologia Alimentaria

Background. Germination can be used to improve the nutritional value of brown rice. The present study investigated treatment methods to enhance the content of a bioactive compound, γ-aminobutyric acid (GABA), and reduce the level of an anti-nutritional factor, phytic acid, in Huyet Rong germinated rice.
Material and methods. The study investigated the effect of temperature (20–40°C), rice:water ratio (1:1 to 1:3), and time (6–24 h) when soaking on the moisture percentage, phytase activity, GABA content, and phytic acid content of brown rice during germination (72 h). Glutamic acid (0–8 mM) and phytase enzyme (0–800 IU/L) were added to the soaking water for GABA synthesis and phytic acid hydrolysis.
Results. Brown rice initially contained 17.32 mg/100 g dry weight (DW) of GABA and 14.14 mg/g DW of phytic acid. It was soaked in distilled water at 30°C with a rice:water ratio of 1:2 (w/v) for 12 h. After that, the grains were germinated in an incubator at 30°C for 24 h. After germination, the GABA content increased to 167.63 mg/100 g DW (an increase of more than 9 times), and the phytic acid level decreased to 9.07 mg/g DW (a decrease of 35.86%). When adding glutamic acid (5 mM) and phytase (600 IU/L) simultaneously to the soaking water, the GABA content after germination increased to 200.41 mg/100 g DW, and the phytic acid level decreased to 6.79 mg/g DW.
Conclusion. Huyet Rong brown rice soaked with glutamic acid and phytase enzyme had higher GABA content (increased nearly 12 times) and less phytic acid content (decreased by about 52%) than untreated brown rice after germination. This method might be applied to improve the biological value of brown rice varieties and to further develop food products from germinated rice.