Changes in physicochemical characteristics of germinated brown rice and brown rice during storage at various temperatures

Abstract

the aim of this study was to investigate changes in physicochemical characteristics of brown rice (BR) and germinated brown rice (GBR) during storage at 4^oC (low temperature) and 37^oC (high temperature) for up to eight months.  The higher storage temperature led to increase in b-value, hardness values and free fatty acid, but a decrease in whiteness index for both BR and GBR.  Although the moisture contents of BR and GBR stored at 37^oC decreased, adequate moisture content was retained for BR stored at 4^oC for eight months.  In contrast, the moisture content of GBR stored at the low temperature was found to increase.  The γ-aminobutyric acid (GABA) contents in all rice samples decreased following storage at 4^oC and 37^oC for eight months.  The low temperature helped maintain the water absorption and hardness of BR and GBR samples, whereas the higher storage temperature seemed to cause both parameters of the samples to rise.  Compared to that of high temperature, low temperature led to a greater increase in free fatty acid with the aging of GBR.  Based on the overall acceptability scores, the panelists preferred cooked GBR to cooked BR.  Both cooked rice varieties nevertheless received lower scores in all sensory attributes after eight months of storage despite the fact that the cooked GBR received better scores in every sensory attributes.  Storage at 37^oC prompted the panelists to reject the aged BR due to low overall acceptability scores of less than five after eight months of storage.  The study results indicate that short storage time at low temperature maintains the physical and chemical characteristics of brown rice and germinated brown rice.

Keywords: Germinated brown rice, Brown rice, GABA, Physicochemical properties