Showing papers on "Brown rice published in 2008"

Speciation and Localization of Arsenic in White and Brown Rice Grains

Abstract: Synchrotron-based X-ray fluorescence (S-XRF) was utilized to locate arsenic (As) in polished (white) and unpolished (brown) rice grains from the United States, China, and Bangladesh. In white rice As was generally dispersed throughout the grain, the bulk of which constitutes the endosperm. In brown rice As was found to be preferentially localized at the surface, in the region corresponding to the pericarp and aleurone layer. Copper, iron, manganese, and zinc localization followed that of arsenic in brown rice, while the location for cadmium and nickel was distinctly different, showing relatively even distribution throughout the endosperm. The localization of As in the outer grain of brown rice was confirmed by laser ablation ICP-MS. Arsenic speciation of all grains using spatially resolved X-ray absorption near edge structure (micro-XANES) and bulk extraction followed by anion exchange HPLC-ICP-MS revealed the presence of mainly inorganic As and dimethylarsinic acid (DMA). However, the two techniques indicated different proportions of inorganic:organic As species. A wider survey of whole grain speciation of white (n=39) and brown (n=45) rice samples from numerous sources (field collected, supermarket survey, and pot trials) showed that brown rice had a higher proportion of inorganic arsenic present than white rice. Furthermore, the percentage of DMA present in the grain increased along with total grain arsenic.

Is there a second fragrance gene in rice

Abstract: Aromatic rice is highly prized by most rice consumers, and many countries cultivate traditional and improved aromatic varieties. 2-Acetyl-1-pyrroline (2AP) is the major aromatic compound in rice, and is believed to accumulate because of an eight-base-pair (8-bp) deletion in an allele at the fragrance locus. In this study, 2AP was quantified and the presence or absence of the fragrance allele (fgr) was determined in 464 samples of traditional varieties of rice from the T.T. Chang Genetic Resources Centre at the International Rice Research Institute. It was shown that a number of aromatic varieties, primarily from South and South-East Asia, do not carry the 8-bp deletion, but 2AP was identified in both raw and cooked rice of these varieties. We suggest that the 8-bp deletion in fgr is not the only cause of aroma, and at least one other mutation drives the accumulation of 2AP. The amount of 2AP in most uniform fgr genotypes was not significantly different from that in aromatic nfgr genotypes, but several fgr genotypes, primarily from South Asia, reproducibly accumulated exceptionally large amounts of 2AP. We suggest that the mutation leading to 2AP in aromatic nfgr varieties possibly originated several times and, through either domestication or evolution, the fgr gene and other alleles leading to 2AP have combined in South Asia, leading to several highly aromatic traditional varieties. The identification of multiple mutations for 2AP will enable rice breeding programmes to select actively for multiple genetic sources of 2AP, leading to the development of highly aromatic and, consequently, high-quality varieties of rice.

Does increased zinc uptake enhance grain zinc mass concentration in rice

Abstract: Rice (Oryza sativa) is the worlds’ most important cereal and potentially an important source of zinc (Zn) for people who eat mainly rice. To improve Zn delivery by rice, plant Zn uptake and internal allocation need to be better understood. This study reports on within-plant allocation and potential Zn accumulation in the rice grain in four so-called aerobic rice cultivars (Handao297, K150, Handao502 and Baxiludao). Two controlled-condition experiments were carried out, one with a wide range of constant Zn concentrations in the medium and one with a range of plant growth rate-related supply rates. In both experiments, increased Zn supply induced increased plant Zn uptake rate throughout crop development, when expressed as daily Zn uptake (l gd ay 21 ) or as daily Zn uptake per gram of plant dry matter (l gg 21 ). Zinc mass concentration (ZnMC) in all plant organs increased with an increase in Zn supply but to various degrees. At higher uptake levels, the ZnMC in stems increased most, while the ZnMC in hulled grains (brown rice) increased least. The increase in leaf ZnMC was generally small, but at toxic levels in the medium, leaf ZnMC increased significantly. It appears that regulation of grain Zn loading differs from regulation of Zn loading to other organs. A milling test on seeds of Baxiludao and Handao502 showed that when ZnMC in brown rice increased from 13 to 45 mg kg 21 , ZnMC in polished rice grains (endosperm) also increased from 9t o 37 mg kg 21 but remained three to five times lower than that in the bran. Irrespective of the ZnMC in the brown rice, around 75% of total grain Zn was present in the endosperm. In both cultivars, there was a major difference in ZnMC between bran and endosperm (120 and 37 mg kg 21 , respectively), suggesting a barrier for Zn transport between the two tissues. There seems to be a second barrier between stem and rachis, as their ZnMCs also differed greatly (300 and 100 mg kg 21 , respectively) in both cultivars at higher plant ZnMC. It is concluded that there is too little scope from a human nutrition perspective to enhance ZnMC in rice endosperm by simply increasing the Zn supply to rice plants because Zn allocation to the endosperm is limited, while observed genotypic differences indicate scope for improvement through breeding.

Metabolite profiling of germinating rice seeds.

Abstract: A metabolite profiling approach based on gas chromatography-mass spectrometry (GC-MS) was used to investigate time-dependent metabolic changes in the course of the germination of rice. Brown rice kernels were soaked and incubated for a total of 96 h under ambient conditions. Samples taken during the germination process were subjected to an extraction and fractionation procedure covering a broad spectrum of lipophilic (e.g., fatty acid methyl esters, hydrocarbons, fatty alcohols, sterols) and hydrophilic (e.g., sugars, acids, amino acids, amines) low molecular weight rice constituents. Investigation of the obtained fractions by GC resulted in the detection of 615 distinct peaks, of which 174 were identified by means of MS. Statistical assessment of the data via principal component analysis demonstrated that the metabolic changes during the germination process are reflected by time-dependent shifts of the scores, which were similar for the three rice materials investigated. Analysis of the corresponding loadings showed that polar metabolites were major contributors to the separation along the first principal component. Relative quantifications based on standardized peak heights revealed dynamic changes of the metabolites in the course of the germination.

Effect of Soaking Temperature on Physical, Chemical and Cooking Properties of Parboiled Fragrant Rice

Abstract: KDML 105 is the most popular fragrant rice for export and consumption in Thailand but it has poor milling yield. To solve this problem, parboiling has been used for improving milling quality of damaged rice. Our present study investigated the effect of soaking temperature on physical, chemical and cooking properties of parboiled rice. The 12-month stored KDML 105 paddy samples were soaked at 40, 50 and 60°C for 3 h, then autoclaved with steam at 121°C 15 min and dried by cabinet tray dryer at 60°C to reach the moisture content of 23 g/100 g dry matter. Head milling yield was significantly increased from 51% in brown rice to 60-80% in parboiled rice. The results also showed that parboiling process significantly (p<0.05) increased protein, lipid and ash contents. Overall, soaking at 50°C for 3 h prior to steaming and drying was found to provide the most desirable quality of parboiled rice in our study in terms of nutritional quality and sensory properties.

Tocopherols, Tocotrienols, and γ-Oryzanol Contents in Japonica and Indica Subspecies of Rice (Oryza sativa L.) Cultivated in Brazil

Abstract: Whole rice contains several fat-soluble phytochemicals such as tocopherols, tocotrienols, and γ-oryzanol which have been reported to possess beneficial health properties. This study was conducted to determine whether brown rice belonging to indica and japonica subspecies were distinguishable from each other regarding the concentration of these compounds by analyzing 32 genotypes. The fat-soluble compounds were analyzed by normal-phase HPLC in a single run. The variability of the compounds analyzed was high, but the mean content of γ-oryzanol across all samples was significantly higher (P < 0.01) in japonica (246.3 mg/kg) than in indica rice (190.1 mg/kg). Similar differences were found for total vitamin E contents which were 24.2 mg/kg in japonica and 17.1 mg/kg in indica rice, respectively. In japonica rice, α-tocopherol, α-tocotrienol, and γ-tocotrienol were the most abundant homologs, while in indica rice the most abundant were γ-tocotrienol, α-tocopherol, and α-tocotrienol. A significant Pear...

Functional properties as affected by laboratory-scale parboiling of rough rice and brown rice.

Abstract: Rough rice (RR) is the conventional feedstock for parboiling. The use of brown rice (BR) instead of RR is gaining interest because it results in shorter processing time and lower energy requirement. This study compared the functional properties of milled parboiled rice under different parboiling conditions from RR and BR. Presoaked RR and BR from cultivars Bolivar, Cheniere, Dixiebelle, and Wells were parboiled under mild (20 min, 100 degrees C, 0 kPa) and severe (20 min, 120 degrees C, 98 kPa) laboratory-scale conditions. Head rice yield improved on the RR and BR samples subjected to severe parboiling and was comparable to that of a commercially parboiled sample. Mild parboiling of BR resulted in lower head rice yields. Parboiling generally resulted in decreased head rice whiteness, decreased apparent amylose, increased total lipid, and sparingly changed protein content. Under the same parboiling conditions, the extent of starch gelatinization was higher for BR compared to RR as manifested by some distinct differences in pasting and thermal properties. The cooking characteristics (water uptake ratio, leached materials, and volumetric expansion) and cooked rice texture (hardness and stickiness) of RR and BR subjected to severe parboiling were fairly comparable. Differences in parboiled rice functional properties due to cultivar effect were evident.

Effects of Pre-Germinated Brown Rice on Blood Glucose and Lipid Levels in Free-Living Patients with Impaired Fasting Glucose or Type 2 Diabetes

Abstract: White rice (WR) is made by polishing brown rice (BR) and has lost various nutrients; however, most people prefer it to BR, maybe because of the hardness of BR. Pre-germinated brown rice (PGBR) improves the problem of BR. It is made by soaking BR kernels in water to germinate and becomes softer than BR. In this study we compared the effects of WR and PGBR on blood glucose and lipid concentrations in the impaired fasting glucose (IFG) or type 2 diabetes patients. Six men and 5 women with impaired fasting glucose (IFG) or type 2 diabetes were randomly allocated to 6 wk on WR or PGBR diet separated by a 2 wk washout interval in a crossover design. Each subject was instructed to consume 3 packs of cooked WR or PGBR (180 g/pack) daily in each intervention phase. Blood samples were collected 4 times (in study weeks 0, 6, 8 and 14) for biochemical examination. Blood concentrations of fasting blood glucose, fructosamine, serum total cholesterol and triacylglycerol levels were favorably improved on the PGBR diet (p<0.01), but not on the WR diet. The present results suggest that diets including PGBR may be useful to control blood glucose level.

Carotenoids in Raw and Parboiled Brown and Milled Rice

Abstract: Color measurements on flour of five raw rice cultivars with different degrees of milling (DOM) showed that red and brown pigments are concentrated in the outer rice layers, i.e. bran and outer endosperm (DOM 15%). The relation between the extinction values and the yellow color parameter (b*) showed that both are representative for the yellow pigment content of flour from rice with DOM lower than 9%. Determinations of the carotenoid levels in raw brown rice samples indicated that carotenoid levels in raw brown rice are lower than in common nonrice cereals. The major brown rice carotenoids are beta-carotene and lutein (both ca. 100 ng/g), while zeaxanthin levels are lower (ca. 30 ng/g). Regression analyses indicated that yellowness, extinction values, and quantitative carotenoid data are related. b*-Values and contents of total carotenoids (r = 0.70), beta-carotene (r = 0.84), lutein (r = 0.78), and zeaxanthin (r = 0.83) were linearly related. However, extinction values (lambda 450 nm) and contents of total carotenoids (r = 0.92), beta-carotene (r = 0.91), lutein (r = 0.89), and zeaxanthin (r = 0.84) showed the best correlations. The three-step hydrothermal treatment parboiling reduces carotenoid contents of brown rice to trace levels. Consequently, pigments do not contribute to the final color of milled parboiled rice.

Dietary starch sources affect net portal appearance of amino acids and glucose in growing pigs.

Abstract: Four male pigs (Duroc × Landrace × Yorkshire; average initial (mean ± SEM) BW = 22.5 ± 1.1 kg), fitted with permanent catheters in the portal vein, ileal vein and carotid artery, were used in a 4 × 4 Latin square experimental design to measure the effect of dietary starch sources on the net portal appearance of glucose and amino acids. Dietary starch sources were resistant starch (RS), maize, sticky rice and brown rice. Diets were provided at 0730, 1530 and 2330 h during a 6-day adjustment period and 1-day collection period. On day 7 of each period, blood samples were collected from the portal vein and carotid artery at 0730 h (prior to feeding) and hourly up to 8 h after meal. Blood samples were used to determine glucose, amino acid, packed cell volume and partial pressure of oxygen (pO2). When calculated per 100 g feed intake, cumulative portal glucose appearance was lower (P < 0.05) for resistant starch than for maize, sticky rice or brown rice up to 8 h after the meal. Cumulative portal glucose appearance was higher (P < 0.05) for sticky rice and brown rice than for other diets until 4 h after the meal, but maize had higher cumulative glucose appearance after 4 h. Net cumulative portal concentrations of most amino acids for resistant starch were also reduced (P < 0.05) than for the other starch sources. Cumulative portal appearance of amino acid represented 48.39%, 63.76%, 61.80% and 59.18% of dietary intake for resistant starch, maize, sticky rice and brown rice, respectively. Collectively, our results indicate that dietary starch sources substantially affect the appearance of amino acids and glucose in the portal circulation.

Changes in Physicochemical Properties of Parboiled Brown Rice during Heat Treatment

Abstract: Thai rice varieties with high amylose content (Chainat 1, Supanburi 1) and low amylose content (Koa Dok Mali 105) were used to produce parboiled brown rice. In this study brown rice with the initial moisture content of 13±1% (w.b.) was soaked at two different initial soaking temperatures of 70 and 80o C. The soaking time was 1h, 2h, 3h and 4h, followed by steaming at temperature of 100oC for 10, 15 and 20 min. The samples were then shade dried at 30±1o C and 60±5 %RH to a final moisture content of 13±1% (w.b.). Physicochemical properties were determined and sensory analysis was performed for selected processing conditions. Head rice yield, yellowness (b-value), whiteness, hardness, water absorption, vitamin E and vitamin B2 were measured and compared with those of commercial parboiled paddy. Results revealed that the head rice yield, color (b-value), cooking time and hardness of parboiled brown rice were decreased whereas whiteness and water absorption were increased compared with commercial parboiled paddy. Qualitatively, parboiled brown rice showed intermediate values between milled rice and commercial parboiled paddy. Sensory analysis revealed high acceptance of cooked parboiled brown rice from the panelists. However, presence of vitamin B2 decreased and vitamin E disappeared after parboiling process on brown rice. Head rice yield was lower for parboiled brown rice when compared to= that of parboiled paddy but greater than the head rice yield of non-parboiled rice.

Evaluation of physicochemical properties of enzyme treated brown rice (Part B)

Abstract: A novel processing technology is developed to polish rice in a more selective way with the help of xylanase and cellulase enzymes of microbial sources. Selective degradation of bran layers has facilitated the retention of vital nutrients and non-nutrient phytochemicals. Antioxidative property of brown rice (PUSA Basmati), its milled fraction and enzyme treated brown rice is evaluated. The overall order of antioxidant activity is brown rice > enzyme treated rice > milled rice. Enzymatic treatment resulted in an increase in water uptake ratio, volume expansion ratio with reduced cooking time over brown rice. Unlike the mechanically milled rice, where great losses are incurred in nutrients and head rice yield, bio-polished rice is produced with better cooking and nutritional attributes.

Enzymatic polishing of rice : A new processing technology

Abstract: A novel processing technology was developed to polish rice in a more selective way with the help of xylanase and cellulase enzymes. The enzymes are produced from Aspergillus sp. and Trichoderma sp., respectively. Brown rice was soaked in water at 35 °C for 24 h to attain a saturated moisture level of 35.5 g/100 g, which leads to an increase in GABA concentration to 27 mg/100 g of rice. Enzymatic treatment was done for 2 h at 50 °C. The enzymes acted upon the non-starch polysaccharides of the bran layers releasing their monomeric sugar constituents, as detected through HPLC. Enzyme degraded surface structure of the rice grain was also studied by Scanning Electron Microscopy. Crude oil and crude fibre content of brown rice was reduced by 16 g/100 g and 20 g/100 g, respectively, through enzymatic treatment over brown rice.

Inhibitory effects of fermented brown rice on induction of acute colitis by dextran sulfate sodium in rats.

Abstract: Although the pathogenic mechanisms of inflammatory bowel diseases are not fully understood, colonic microbiota may affect the induction of colonic inflammation, and some probiotics and prebiotics have been reported to suppress colitis. The inhibitory effects of brown rice fermented by Aspergillus oryzae (FBRA), a fiber-rich food, on the induction of acute colitis by dextran sulfate sodium (DSS) were examined. Feeding a 5% and 10% FBRA-containing diet significantly decreased the ulcer and erosion area in the rat colon stained with Alcian blue. In another experiment, 10% FBRA feeding decreased the ulcer index (percentage of the total length of ulcers in the full length of the colon) and colitis score, which were determined by macroscopic observation. It also decreased myeloperoxidase activity in the colonic mucosa. Viable cell numbers of Lactobacillus in the feces decreased after DSS administration and was reversely correlated with severity of colitis, while the cell number of Enterobacteriaceae increased after DSS treatment and was positively correlated with colitis severity. These results indicate that FBRA has a suppressive effect on the induction of colitis by DSS and suggest FBRA-mediated modification of colonic microbiota.

Preventive effect of fermented brown rice and rice bran on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastric carcinogenesis in rats.

Abstract: A number of possible preventive agents for cancers in different organs have been reported, however, little information is available regarding the effective agents for the development of gastric cancers. The rice components are known to be effective for the prevention of the development of cancers. Our group has demonstrated that fermented brown rice by Aspergillus Orzae (FBRA) has chemopreventive potentials in several organs. In this study, we investigated the modifying effects of FBRA exposed during the initiation or post-initiation phase of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced gastric carcinogenesis in rats. Five-week-old male ACI rats were divided into 7 groups. Groups 1-5 were given oral administration of MNNG (100 mg/l in distilled water) for 24 weeks starting at 6 weeks of age. Groups 2 and 3 were fed a diet containing 5 and 10% FBRA during the initiation phase, respectively, whereas groups 4 and 5 were fed these diets during the post-initiation phase. Group 6 was given a diet containing 10% FBRA throughout the experiment. Group 7 was kept on the basal diet alone and served as an untreated control. Rats were sacrificed at 52 weeks after the start, and the epithelium of the stomach was investigated in detail. Incidence and multiplicity of gastric proliferative lesions of group 1 (MNNG alone) were 61% and 1.67+/-1.57/rat, respectively. Those of group 5 (25%, 0.35+/-0.67) which were given FBRA at a dose of 10% during the post-initiation phase were significantly less than those of group 1. Furthermore, the same group expressed a significantly decreased Ki67-labeling index in the non-lesional gastric epithelium when compared to that of group 1. These results indicate that FBRA inhibits MNNG-induced development of gastric tumors by administration during the post-initiation phase in rats. FBRA is regarded as a promising dietary agent for the prevention of human gastric cancer.

Effect of hulling and milling on the physical properties of rice grains

Abstract: Basic physical properties of agricultural materials play important role for optimizing the design of equipment and fa- cilities for the harvesting, handling, conveying, separation, drying, storing, and processing. In this study, some physical properties of three rice varieties, namely Tarom Mahali, Fajr, and Neda, at three levels of processing, which name rough rice (paddy), brown rice (husked or hulled), and white rice (milled) were investigated. The thousand grains mass and porosity decreased significantly with the rice processing, but the bulk density increased. The rough rice of each variety showed the least value of true density. Unit mass and volume of rice grain decreased with the rice processing. Totally, the static coefficient of friction affected by cultivars, levels of pro- cessing, and frictional materials. By processing, the filling angle of repose for all cultivars decreased. The terminal velocity increase significantly for every variety. It was observed that the terminal velocity of the rice's hull and bran is lower than for the rough rice, brown rice, milled rice.

Production of black rice cake using ground black rice and medium‐grain brown rice

Abstract: Puffed rice cakes were produced from a blend of ground black rice (GBR) and medium-grain brown rice (GMBR) by using a rice cake machine. Effects of moisture content, heating temperature and heating time on quality of the black rice cake were investigated. The specific volume of black rice cakes showed an increasing trend with increasing tempering moisture, heating temperature and heating time. The hardness of puffed black rice cake decreased as tempering moisture and heating time increased, and was influenced more by GMBR content than heating temperature. In general, the black rice cake lightness and yellowness decreased steadily with increasing GBR content, while tempering moisture, heating temperature and heating time did not significantly affect the colours of black rice cake. On the contrary, the redness increased with increasing GBR contents. The weight loss during tumbling was not found at all puffing conditions.

Methodology for Assessing Rice Varieties for Resistance to the Lesser Grain Borer, Rhyzopertha dominica

Abstract: Several physical and chemical attributes of rice were evaluated to determine which character would be best to use to assess multiple rice varieties for resistance to the lesser grain borer, Rhyzopertha dominica (F.). Laboratory tests were conducted on single varieties of long-, short-, and medium grain-rice to develop procedures and methodologies that could be used for large-scale screening studies. Progeny production of R. dominica was positively correlated with the percentage of broken hulls. Although kernel hardness, amylose content, neonate preference for brown rice, and adult emergence from neonates varied among the three rice varieties tested they did not appear to be valid indicators of eventual progeny production, and may not be useful predictors of resistance or susceptibility. Soundness and integrity seem to be the best characters to use for varietal screening studies with R. dominica.

Genotypic variation of mineral elements contents in rice (Oryza sativa L.)

Abstract: Mineral nutrition of potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn) are important for human health. The method of inductively coupled plasma mass spectrometry (ICP-MS) was employed to determinate the contents of K, Ca, Na, Mg, Fe, Zn, Cu and Mn in milled rice (Oryza sativa L.) of 274 rice genotypes. The results showed that the visible difference could be found for the contents of eight elements in milled rice among rice genotypes studied. It existed the possibility to select the genotype(s) with abundant of mineral nutrient from the genetic resource. Meanwhile, the contents of mineral elements in brown rice were significantly higher than those in milled rice. The averages of K, Mn and Cu contents of indica rice were significantly lower than those of japonica rice, while no significant difference was found for other five element contents between indica and japonica rice genotypes. The average contents of Na and Cu in non-glutinous rice genotypes were higher than those in glutinous ones, whereas the averages of K and Mn contents in non-glutinous rice genotypes were lower in present experiment. Additionally, the K, Ca and Mg contents of milled rice from white brown rice were significantly higher than those from red brown rice, and Ca content of milled rice from white brown rice was also visibly higher than that from black brown rice. For microelements, significant difference was observed for Zn content between milled rice from red and white brown rice, or between milled rice from red and black brown rice. Some genotypes with abundant mineral nutrient in milled rice had been selected and could be used in rice nutrient breeding.