An Improved Process for High Quality and Nutrition of Brown Rice Production

Germinated brown rice (GBR) of two popular Thailand varieties, Khao Dawk Mali 105 (KDML 105) and Chainat 1, with improved nutritional composition, was obtained by optimizing water soaking conditions. Different water pH (3, 4, 6 and 8), temperatures (25 degrees C, 35 degrees C and 45 degrees C), and soaking times (12 and 24 h) were tested. Using the response surface methodology (RSM), the best condition for producing GBR of both varieties was soaking in water with pH 6 and temperature of 35 degrees C for 24 h. It caused a 4- to 5-fold increase in gamma-amino butyric acid (GABA) content which, together with protein and lipid contents, were highest among treatments. Intermediate levels of thiamine (vitamin B1) and phytic acid (IP6) were obtained. In GBR of KDML 105 variety, GABA, vitamin B1 and IP6 contents were 16.48, 0.526 and 501.06 mg/100 g, respectively, while protein and lipid contents were 10.50% and 4.00%, respectively. For Chainat 1 variety, GABA, vitamin B1 and IP6 contents were 14.50, 0.436 and 486.03 mg/100 g, respectively, while protein and lipid contents were 9.80% and 3.99%, respectively. Carbohydrate and amylose contents differed by only less than 1-2% among treatments. Supplemental aeration during water soaking decreased GABA, protein and lipid contents, but increased vitamin B1 and IP6 contents in both varieties. Furthermore, cooked GBR of both varieties had softer texture than cooked ordinary brown rice.