No abstract

Rice grains rich in gamma-aminobutyric acid (GABA) are increasing in popularity, particularly in the health food market. GABA levels in rice are influenced by many factors, including the duration of incubation of seeds, particularly in pre-germinated brown rice grains. In this report, five different incubation durations (0,12, 24, 36, and 48 h) and 21 rice varieties (11 landraces purple rice and 10 modern white varieties) were tested. Results show that GABA content increased steadily from 3.96 mg/100 g dry matter at 0 h duration (i.e., no incubation period) to 10.04 mg/100 g dry matter after 12 h, reaching the highest levels of 17.87 mg/100 g dry matter at 24 h incubation, and then decreased continuously afterwards to 9.91 and 1.36 mg/100 g dry matter at 36 and 48 h, respectively. A correlation of GABA levels at 0 h and 24 h was detected (r = 0.48). Genotypic variation was detected from a minimum of 6.50 to a maximum of 10.10 mg/100 g dry matter, with a mean of 8.03. At 24 h, the white rice variety KDML 105 and the purple rice variety Kum Doi Saket (23.48 and 23.63 mg/100 g dry matter, respectively) exhibited the highest GABA content of all 21 rice varieties. This indicates the importance of the local purple rice cultivars for adding nutritional value to functional food products.

No abstract

This study aims to determine the effect of heat treatments on milling quality and some nutrients of germinated glutinous purple rice; we performed an experiment in a 3x2 factorial design with three replications. The first factors were three heating methods, namely; baking (80, 100 °C) and steaming (100 °C), and the second factors were two heating periods (15 and 30 min). Dried germinated rice was used as control. Heating method and duration as well as their interactions, significantly affected the milling quality and anthocyanin extraction (P < 0.05). Steaming at 100 °C for 30 min significantly increased head rice (73.4%), while baking at 100 °C for 30 min resulted in the highest amount of broken rice (42.3%). These method also maintained the GABA (γ-aminobutyric acid) content of the rice, while anthocyanin extraction was decreased from 52.1 to 29.9 mg•g -1 . Heating at 80 °C for 30 min, 100 °C for 10 and 20 min and 125 °C resulted in a higher free radical scavenging ability when compared to unheated rice.