Brown rice

About: Brown rice is a research topic. Over the lifetime, 8180 publications have been published within this topic receiving 81079 citations.

Influence of growth temperature on the amounts of tocopherols, tocotrienols, and gamma-oryzanol in brown rice.

Abstract: Brown rice is a valuable source of lipid-soluble antioxidants including ferulated phytosterols (i.e., gamma-oryzanol), tocopherols, and tocotrienols. To evaluate the impact of temperature on the accumulation of these compounds, seeds from six different rice lines grown to maturity in replicate greenhouses in Gainesville, FL, were analyzed. The lines represented Oryza sativa indica, O. sativa japonica, and Oryza glaberrima of different origins. Temperatures were maintained near ambient at one end of each greenhouse and at approximately 4.5 degrees C above ambient at the other end. gamma-Oryzanols, tocopherols, and tocotrienols were extracted from whole seed (i.e., brown rice) and analyzed by HPLC. Tocotrienols and tocopherols varied widely between lines but changed only slightly with respect to temperature. In general, the proportions of alpha-tocotrienol and/or alpha-tocopherol increased at elevated temperature, whereas gamma-tocopherol and gamma-tocotrienol decreased. Six gamma-oryzanol peaks, identified on the basis of absorbance maxima at 330 nm and HPLC-mass spectrometry, were quantified. The most abundant component was 24-methylenecycloartanyl ferulate, present at 40-62% of total. Its levels increased 35-57% at elevated temperature in five of six lines, accounting for most of the change in total gamma-oryzanol. The results suggest that the physiological action of individual ferulated phytosterols should be investigated because their relative proportions in gamma-oryzanol can change.

Postprandial blood glucose and insulin responses to pre-germinated brown rice in healthy subjects

Abstract: Effects of pre-germinated brown rice (PGBR) on postprandial blood glucose and insulin concentrations were compared with brown rice (BR)and white rice (WR) in two studies. In the first study, we investigated the time course of postprandial blood glucose and insulin concentrations after ingesting 25% (W/V) glucose solution, PGBR, BR or WR in 19 healthy young subjects. In the second study, dose-dependent effect of PGBR on the time course of postprandial blood glucose concentrations was compared among 4 different mixtures of PGBR and WR in 13 healthy young subjects. They were solely PGBR, 2/3 PGBR(PGBR:WR= 2 : 1), 1/3 PGBR (PGBR : WR=1 : 2) and solely WR. Each sample was studied on a different day. The samples were selected randomly by the subjects. All the rice samples contained 50g of available carbohydrates. The previous day the subjects ate the assigned dinner by 9 : 00 pm and then were allowed only water until the examination. The next morning, they ingested each test rice sample with 150ml of water in 5-10min.Blood was collected into capillary tubes from finger at 0, 30, 60, 90 and 120 min after the ingestion. The incremental areas under the curve (IAUC) of blood glucose concentrations (IAUC-Glc) for 120min after the administration of PGBR and BR were lower than those after WR. In contrast the IAUC-Glc of BR and PGBR were not different (Study 1). The higher the ratio of PGBR/WR, the lower the glycemic index became (Study 2). These results suggest that intake of PGBR instead of WR is effective for the control of postprandial blood glucose concentration without increasing the insulin secretion.

γ-Aminobutyric acid (GABA) content in different varieties of brown rice during germination

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.

Improved plant growth and Zn accumulation in grains of rice (Oryza sativa L.) by inoculation of endophytic microbes isolated from a Zn Hyperaccumulator, Sedum alfredii H.

Abstract: This study is to investigate the possibility of zinc (Zn) biofortification in the grains of rice (Oryza sativa L.) by inoculation of endophytic strains isolated from a Zn hyperaccumulator, Sedum alfredii Hance. Five endophytic strains, Burkholderia sp. SaZR4, Burkholderia sp. SaMR10, Sphingomonas sp. SaMR12, Variovorax sp. SaNR1, and Enterobacter sp. SaCS20, isolated from S. alfredii, were inoculated in the roots of Japonica rice Nipponbare under hydroponic condition. Fluorescence images showed that endophytic strains successfully colonized rice roots after 72 h. Improved root morphology and plant growth of rice was observed after inoculation with endophytic strains especially SaMR12 and SaCS20. Under hydroponic conditions, endophytic inoculation with SaMR12 and SaCS20 increased Zn concentration by 44.4% and 51.1% in shoots, and by 73.6% and 83.4% in roots, respectively. Under soil conditions, endophytic inoculation with SaMR12 and SaCS20 resulted in an increase of grain yields and elevated Zn concentrations by 20.3% and 21.9% in brown rice and by 13.7% and 11.2% in polished rice, respectively. After inoculation of SaMR12 and SaCS20, rhizosphere soils of rice plants contained higher concentration of DTPA-Zn by 10.4% and 20.6%, respectively. In situ micro-X-ray fluorescence mapping of Zn confirmed the elevated Zn content in the rhizosphere zone of rice treated with SaMR12 as compared with the control. The above results suggested that endophytic microbes isolated from S. alfredii could successfully colonize rice roots, resulting in improved root morphology and plant growth, increased Zn bioavailability in rhizosphere soils, and elevated grain yields and Zn densities in grains.