White Rice Grains Research Articles

Analysis of Fungal Contamination on Commercially Sold Rice in Puerto Rico

Crops and stored grains are susceptible to pathogens that represent a threat to our health. The study presented herein compares the normal surface and endophytic fungal communities present on white and brown rice grains. One hundred grains of each rice variety was analyzed to determine their fungal contaminants and endophytes. Fungi were inoculated on SDA media, and purified in PDA media; morphological characterization was performed followed by amplification of the ITS region using PCR for all fungal isolates. Statistical analysis indicated significant differences between medium brown rice compared to white rice for surface and endophytic communities (p-value £ 0.05). In addition, a higher fungal diversity was found on brown rice grains compared to white rice. This variation may be due to differences in the processing methods used for each rice grain type. BLAST analysis revealed the presence of toxigenic strains of Aspergillus flavus, A.oryzae, Penicillium verrucosum, and P. viridicatum. The study of fungal growth in rice grains can contribute to the minimization of mycotoxin production by its prevention and control; therefore, decreasing crop contamination and human exposure to their metabolites. KEYWORDS: Fungi; Rice; Fungal contaminants; Fungal endophytes

Metabolite profiling and antioxidant activities of white, red, and black rice (Oryza sativa L.) grains

In the present study, several lipids- and water-soluble metabolites from white, red, and black rice were analyzed using HPLC–DAD, GC–FID, and GC–MS/MS. The quantitative data showed that black rice contains the highest amount of cyanidin (4.34 mg/g), γ-oryzanol (380.2 µg/g), total folate (39.1 µg/100 g), tocols (tocopherols and tocotrienols; 21.7 µg/g), all-E-lutein (7.14 µg/g), polyunsaturated fatty acids (37.7%), and total phenolic contents (4.88 mg gallic acid eq./g). Additionally, the ascorbic acid equivalent (AAE) antioxidant assays showed that the metabolites from black rice were potent scavengers of ABTS cations (18.99 mg AAE/g) and DPPH radicals (16.20 mg AAE/g), probably because of the presence of high contents of phenolic (e.g., anthocyanin) and non-phenolic compounds (e.g., carotenoids, tocols, and γ-oryzanols). Among the studied metabolites, the least variation was recorded for fatty acid composition. In the three types of rice grains, oleic acid (C18:1n9c) was found in the highest quantity (38.60–40.35%), followed by linoleic (LA; C18:2n6c) and palmitic acid (C16:0) (18.90–21.15%). Overall, black rice was found to be the most abundant source of nutritionally important compounds, followed by red rice and white rice. Thus, this study provides a basis for the incorporation of pigmented rice into our daily diet for potential health benefits.

Effect of starch modification in the whole white rice grains on physicochemical properties of two contrasting rice varieties

The effect of acetylation of milled rice of selected rice varieties viz. TDK8 and DG on their physicochemical properties was investigated at different acetic anhydride concentrations (1–7 g per 100 g of milled rice samples in 225 mL of water). Results showed that the intact starch of milled grains of both selected verities could be acetylated (Acetyl % for TDK8 = 2.18 and for DG = 0.89) even with 1 g of acetic anhydride. X-ray diffraction patterns showed that acetylation resulted in reduced crystallinity. Acetylation resulted in reduced peak and final viscosities and gel strength, particularly in glutinous (TDK 8) and non-glutinous (DG) rice. Thermal study showed acetylation resulted in reduced thermal transition temperatures and enthalpy of both varieties. Although the increase in retrogradation thermal temperatures was observed, the amount of retrograded starch was decreased in both varieties. Furthermore, the texture of cooked acetylated grains was less hard and more adhesive. In vitro digestion showed significant decrease in GI possibly due to structural changes in the native starch during acetylation. These findings suggest a good potential of applying acetic anhydride pre-treatments in rice processing, especially glutinous varieties to control the hardness and maintain the stickiness properties of rice.

Sickle Cell Sperm Selection with Hb-S Mab: A Future Application for Intracytoplasmic Genotypically Selected Sperm Injection (IGSI)

The Current study revealed the natural occurrence of toxigenic fungi and mycotoxins production in grains in Saudi Arabia. Samples of yellow corn, white rice and red corn grains were collected from different local markets. Three fungal isolates were isolated from the examined corn grains using PDA media. Alternaria sp were the most prominent fungi in yellow corn grains, white rice and red corn grains. Three Alternaria sp isolated were identified using molecular characterization of Actts gene. DNA genome of the three Alternaria sp isolates (namely AWR; AYC and ARC which corresponds to isolates from white rice, yellow corn, red corn) was used as a template for PCR to amplify Actts gene. Partially sequenced Actts gene was amplified using a specific primer set to confirm its identity, phylogenetic relationships between the three isolates as well as determination of the corresponding antigenic determinants. The epitope prediction analysis demonstrated that there were 5, 6 and 5 epitopes whose score were above 0.90 in AWR, AYC and ARC, respectively. Interestingly, there were great variations in the epitope sequences among the three isolates except for the epitope, VYGASTATGTLAVQ. This work led to molecular identification of three Alternaria sp. using Actts toxin gene and the unique antigenic determinants that could be used for design of a broad spectrum antibody for rapid detection of Alternaria sp. in foods.

Comparative Studies on Proximate and Some Mineral Composition of Selected Local Rice Varieties and Imported Rice Brands in Ghana

Purpose: The objective of this study was to determine and compare the proximate and mineral (Fe, Zn, Mn, Mg, Se) composition of locally produced polished and unpolished rice and two imported rice brands. Design/methodology/approach: The proximate and mineral (Fe, Zn, Mn, Mg, Se) composition of five local rice varieties (Maawuwoe coop brown rice, Maawuwoe coop white rice, Shigafa brown rice, Shigafa white rice and long grain parboiled rice) and two imported brands of rice (Imported 1 and 2) were evaluated using standard methods after which they were compared to establish which had the higher percentage of nutrients. Findings: The percentage protein of the imported rice brands (7.0-8.4%) were significantly higher (p<0.05) than those of the local rice varieties (5.69–6.89%). The local varieties had comparable carbohydrate (74.20-79.41%) but significantly higher fat (1.1-2.57%) and fibre (0.64-1.95%) contents than the imported brands (76.94-78.21% carbohydrate, 0.49-0.88% fat and 0.5% fibre). Maawuwoe coop brown rice had significantly higher Fe and Zn contents of 96 mg/100g and 2.9 mg/100g respectively and Shigafa brown rice recorded the highest Mn content of 1.81 mg/100g. Imported brand 1 however had the highest Mg content (96 mg/100g). For the local varieties, the brown had higher fibre contents (1.95-1.65%) than that observed in the white. Originality/value: This study is meant to provide knowledge on the nutritional quality of local rice to inform consumer and subsequently enhanced patronage in Ghana.

Preparation of arsenic‐containing white rice grains as calibration standards for X‐ray fluorescence analysis of total arsenic in cereals

A preparation method of arsenic‐containing white rice grains as calibration standards was developed for the X‐ray fluorescence (XRF) analysis of arsenic in rice grains. Calibration standards were prepared by adding 10 g of white rice grains (from Japan) to 100 ml methanol‐containing dimethylarsinic acid corresponding to 2–100 µg arsenic. The mixture was heated, dried at 150 °C, cooled to room temperature, and then stored in a silica gel desiccator. A total of 5.0 g of each calibration standard was packed into a polyethylene cup (32 mm internal diameter and 23 mm height) covered with a 6‐µm‐thick polypropylene film and then analyzed by wavelength‐dispersive XRF spectrometry. The calibration curve for arsenic obtained from the white rice grains containing arsenic showed good linearity over a concentration range of 0.21–5.00 mg kg−1 arsenic. The limit of detection of arsenic was 0.080 mg kg−1. To check the reliability of the XRF method, the concentrations of arsenic in six samples of grain cereals and two samples of flour were compared with those obtained by atomic absorption spectrometry after acid decomposition. The values obtained by both analytical methods showed good agreement. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Prevalence of viable &lt;i&gt;Monascus&lt;/i&gt; van Tieghem species in fermented Red Rice (Hong Qu Mi) at consumer level in Selangor, Malaysia

Red rice is a fermented product consumed widely throughout Asian countries as food colorant, food flavour and food preservative. Fermentation of red rice is accomplished by inoculating individual or several Monascus species onto white rice grains during which time the fungal starters biosynthesize the intense red pigments which are subsequently assimilated into the final product. The present work was undertaken to establish the prevalence of viable Monascal fungal starters involved in red rice fermentation from red rice samples obtained at consumer level in Selangor, Malaysia by means of morphological characterization. Macromorphology examined the size and texture of colonies on growth plates, and colony growth rates while micromorphology assessed the size and shape of conidiospores and texture of conidiophores and hyphae. A total of 50 red rice samples were obtained from which isolation and characterization of Monascal fungal starters were performed. From the red rice samples, Monascus purpureus Went was found to be the key Monascal fungal starter from which the isolation frequency was 58% as compared to that of Monascus pilosus K. Sato which was 42%. No strain of Monascus ruber van Tieghem was isolated. Since 100% of red rice samples gave viable spores which germinated at favourable conditions, there is an elevated risk of citrinin contamination of the final product. Therefore, further mycological and toxicological analyses on fermented red rice are warranted to raise public awareness on consumption of red rice.

Mercury Emission from Artisanal Buladu Gold Mine and its Bioaccumulation in Rice Grains, Gorontalo Province, Indonesia

Available forms of mercury (Hg) released from artisanal gold mine activities could be taken up increasingly by plants via root and leaf stomata. Total mercury (THg) concentrations in dry deposit, surface soil and rice grains were investigated as well as the potential risks in september 2011 from three rice fields of concern. The results revealed that the concentrations of THg in dry deposition, top soil (0 to 5 cm depth), sub soil (6 to 10 cm depth) and rice grains (Oriza sativa L.) both brown (once milled) and white (twice milled) grains were ranged from 166 to 322 m-2 day-1, 484 to 4244 μg kg-1dw, 122 to 1812 μg kg-1ww, and 113 to 1084 μg kg-1ww, respectively. Hazard quotient (HQ) values for dry deposition, top soil and sub soil were ranged from 3 to 7, 5 to 42 and 5 to 36, respectively. Target hazard quotient (THQ) for brown and white rice grains consumptions were found in the range of 0.1 to 1.6 and 0.1 to 1.0, respectively. THQ values through brown rice consumption exceeded the guideline (&gt;1) presented that the brown rice in these areas should not be safe for consumption and are at risks for the whole lifespan. However, the THQ values of both brown and white rice grains in some areas were still low and should be safe for the whole life span consumption.

Identification and quantification of phenolic acids and anthocyanins as antioxidants in bran, embryo and endosperm of white, red and black rice kernels (Oryza sativa L.)

Whole rice grain comprising endosperm, embryo (or germ), and bran has potential beneficial health effects in addition to provision of nutrients. The distribution of phenolic acids and anthocyanins in endosperm, embryo, and bran of white, red, and black rice grains was investigated in this study. The total phenolic content (TPC) was highest in the bran, averaging 7.35 mg GAE/g and contributing 60%, 86% and 84% of phenolics in white, red and black rice. The average TPC of the embryo and endosperm were 2.79 and 0.11 mg GAE/g accounting for 17% and 23%, 4% and 10% and 7% and 9% in white, red and black rice, respectively. The antioxidant capacity determined using DPPH and ORAC displayed a trend similar to TPC. Free/conjugated phenolic acids in white, red and black rice bran accounted for 41%, 65% and 85% of total acids. Bound phenolic acids in rice bran accounted for 90% of total acids in whole grain. Cis-p-coumaric was detected in bound form in bran while cis-sinapic acid was detected in the free/conjugated form in embryo and bran. Cyanidin-3-O-glucoside and peonidin-3-O-glucoside were identified mainly in black rice bran as the total anthocyanins. Cyanindin-3-O-rutinoside was also detected in black rice bran.

Preparation of cadmium-containing brown rice grains as calibration standards for X-ray fluorescence analysis of cadmium in rice grains

A preparation method for Cd-containing brown rice grains as calibration standards was developed for X-ray fluorescence (XRF) analysis of Cd in rice grains. Calibration standards were prepared by adding 10 g of base rice grains (from Japan) to 100 ml of methanol containing 5−100 µg of Cd. The mixture was heated, cooled, and stored in a silica gel desiccator. Seven grams of each calibration standard was packed into a polyethylene cup (32-mm internal diameter and 23-mm height) covered with a 6-µm-thick polypropylene film and then subjected to XRF analysis. The calibration curves of Cd in brown and white rice grains showed good linearity in 0.50−10 mg kg−1. The detection limits of Cd in brown and white rice grains were 0.14 and 0.12 mg kg−1, respectively. The slopes of the calibration curves for Cd in brown and white rice grains were slightly different owing to absorption effects. The absorption effects were corrected using the ratio of the intensity of Cd Kα to that of Rh Kα-Compton scattering. After correction, the calibration curves of Cd in brown and white rice grains showed identical slopes. The spike test for 5 mg kg−1 of Cd in white rice grains (from Thailand), using the corrected calibration curves, showed quantitative recoveries (92−97%). Copyright © 2013 John Wiley & Sons, Ltd.

Effect of Extraction on Phenolic Antioxidant of Different Thai Rice (Oryza Sativa L.) Genotypes

Acid hydrolysis and shaking extraction methods were used to extract nine genotypes of Thai rice grains. The extracts were determined total phenolic including anthocyanin contents and antioxidant capacities using 2,2-diphenyl-1-picrylhydrazyl and the ferric thiocyanate assays from white, red, and black rice grains. The results demonstrated that the extraction methods affected phenolic antioxidant of rice grains. The values of insoluble phenolic compounds were significantly higher than those of soluble phenolic compounds, which was about 1.3 times. The soluble anthocyanin content of grains was low comparing to the insoluble anthocyanin content. In addition, among studied rice grains, black rice possessed the highest phenolic and anthocyanin contents as well as antioxidant capacities. These findings suggested that black rice can be further explored as a functional food.

Effects of Parboiled Rice Diet on Oxidative Stress Parameters in Kidney of Rats with Streptozotocin-Induced Diabetes

The effect of parboiled rice (PR) and white rice (WR) diets on oxidative stress (OS) parameters was investigated in the kidneys of rats with streptozotocin-induced diabetes (40 mg kg(-1), iv). The experimental groups (n=8) were control fed with PR (CPR), control fed with WR, diabetic fed with PR, and diabetic fed with WR. After 30 days of treatment, all animals were anesthetized and exsanguinated before removal of kidneys, which were used to determine thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, carbonyl protein, superoxide dismutase, catalase, glutathione peroxidase (GPx), glutathione reductase, glutathione-S-transferase activities, and levels of glutathione (GSH). Total phenolic compounds were determined in WR and PR grains. Our data indicated that diabetes induced increase in TBARS and lipid hydroperoxides levels. Although PR has not prevented the rise in the levels of these measurements, its consumption by our animals resulted in higher GPx activity and GSH content than that of the CPR. Moreover, PR also presented concentration of total phenolic compounds 127% higher than WR grains. Thus, its consumption in this diabetic condition is suggested because this seems to confer greater protection against OS in the renal tissue of diabetic animals.

Effect of rice parboiling on performance and metabolic responses in rats

This research is aimed at evaluating the effect of rice grains submitted to different processing (white or parboiling) on performance and biological responses in rat. Male Wistar rats were fed with diets containing white or parboiled rice grains of the cultivar IRGA 417. Wet and dry faecal production, fasting serum glucose concentration, serum total protein and organs' weights as liver, kidney and epididymal fat pads were not affected by processing. The animals in the treatment with parboiled rice showed higher body weight gain, feed intake, nitrogen excretion, serum triglycerides, uric acid levels and pancreas weight and lower feed conversion, faecal pH, albumin and serum HDL cholesterol, when compared with the treatment with white rice. The results obtained in this work allow the conclusion that structural change of rice components caused by parboiling results in variations in different essential body metabolic parameters, such as body weight gain, gastrointestinal function and glycaemic control.

일반계 및 통일계 다수확 쌀 품종의 취반 특성

This study examined physicochemical properties of rice grains and qualities of cooked white rice of the high yielding, Japonica type, specifically Druryechanbyeo and Boramchanbyeo, and of the Tongil-type, specifically Hanarumbyeo and Andabyeo. The changes of water absorption rate of rice grains, their textural properties and a sensory evaluation of the cooked rice s were analyzed. All varieties were short grain. The length and width of Tongil type rice grains larger than those of Japonica type. The water absorption of white rice grains increased rapidly until 1 hr when soaking and after that increased slightly. The water absorption of Druryechan grain was higher than that of the Boramchan. The sensory evaluation results showed that the Japonica type cooked rices had a higher value for overall quality than the Tongil type cooked rices. With regard to the textural properties of the cooked rices, the hardness of Boramchan and Hanarum varieties showed higher than that of Druyechan and Anda varieties. Adhesiveness, springiness and chewiness were not significantly different between varieties (p<0.05).

Decontamination Effect of Milling by a Jet Mill on Bacteria in Rice Flour

The decontamination effect of milling by a jet mill was investigated by counting the number of bacteria in brown and white rice flour with mean particle diameters of 3, 20, and 40µm prepared by the jet mill. In the jet mill, the particles are crushed and reduced in size by the mechanical impact caused by their collision. Although the brown and white rice grains were contaminated with approximately 10(6) and 10(5) CFU/g bacteria, the microbial load of the rice flour decreased as the mean particle diameter decreased, ultimately decreasing to approximately 104 and 103 CFU/g in the brown and white rice flour. The temperature and pressure changes of the sample were not considered to have an effect on reducing the bacterial count during the milling. Hence, it was thought that the rice flour was decontaminated by other effects.

Speciation of methylmercury in rice grown from a mercury mining area

Monomethylmercury (CH 3Hg + and its complexes; MeHg hereafter) is a known developmental neurotoxin. Recent studies have shown that rice ( Oryza sativa L.) grain grown from mercury (Hg) mining areas may contain elevated MeHg concentrations, raising concerns over the health of local residents who consume rice on a daily basis. An analytical method employing high performance liquid chromatography (HPLC) – inductively coupled plasma mass spectrometry (ICP-MS) following enzymatic hydrolysis was developed to analyze the speciation of MeHg in uncooked and cooked white rice grain grown from the vicinity of a Hg mine in China. The results revealed that the MeHg in the uncooked rice is present almost exclusively as CH 3Hg- l-cysteinate (CH 3HgCys), a complex that is thought to be responsible for the transfer of MeHg across the blood–brain and placental barriers. Although cooking does not change the total Hg or total MeHg concentration in rice, no CH 3HgCys is measurable after cooking, suggesting that most, if not all, of the CH 3HgCys is converted to other forms of MeHg, the identity and toxicity of which remain elusive.

Microbial Population, Aflatoxin Contamination and Predominant Aspergillus Species in Korean Stored Rice

We evaluated microbial populations and aflatoxin production in unhulled and white rice from rice processing complexes of the National Agricultural Cooperative Federation in five regions in Korea and identified three predominant Aspergillus species. Fungal and bacterial populations in rice samples were significantly different between regions in 2007. Aflatoxins were also detected and varied at the levels of 2.45 - 3.43 ng per g unhulled rice grain and 1.29 - 2.09 ng per g white rice grain. Unhulled rice generally detected higher level of aflatoxins than white rice regardless of sampling regions; however, no significant differences were found in Anseong and Cheonan in 2005 and Cheonan and Gimpo in 2007. Aflatoxin production between sampling regions was not different regardless of rice type and sampling year. Although the fungal diversity was highly distinct from region to region, three Aspergillus isolates were predominant in the rice samples; thus, representative isolates AC317, AF57, and AF8 were selected and identified based on their morphological and molecular characteristics. Consequently, isolates AC317, AF57, and AF8 were identified as A. candidus, A. flavus, and A. fumigatus, respectively. These fungi can produce mycotoxins that are harmful for consumers and thus it is important to detect and reduce the population of storage fungi in rice.

A Linear Driving Force (LDF) Approximation of Moisture Diffusion Kinetics in White Rice

Soaking characteristics of white rice grain in water are studied at 25, 40, 60, 70 and 80 °C. The kinetics of mass transfer are modeled using a linear driving force (LDF) approximation with constant diffusivity, which is capable of predicting the moisture ratio profile with time. This approximation is a relatively new approach in food engineering applications for systems in which the rate of mass transfer is controlled by intra-particle diffusion and nonlinear adsorption through porous adsorbent. The mass transfer is also modeled through Fick's law for unsteady-state diffusion using finite difference (FD) method, and compared with the LDF model. In general, the moisture uptake curves calculated with this new approximation compare favorably with the finite difference solution obtained in spherical coordinates, producing results of similar accuracy. Both the methods give a good agreement with the experimental data. The values of the effective diffusion coefficients are between 7.33×10-11 m2/s and 1.43×10-10 m2/s for a temperature of 25 and 80 °C respectively. Although gelatinization of starch is observed at a higher temperature which influences the increase in moisture content, the moisture uptake curves calculated with this new approximation compare favorably with the numerical solution of the non-linear diffusion equation. As such, it can be safely used to predict the unsteady-state moisture absorption kinetics of a rice grain, for the temperature range investigated.

Speciation and Localization of Arsenic in White and Brown Rice Grains

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.

Analysis of phenolic compounds and antioxidant activity with H4IIE cells of three different rice grain varieties

The phenolic content and the antioxidant capacity of ethanolic extract of rice grains were examined using three different rice (Oryza sativa L. var. japonica) varieties, Jakwangchalbyeo (red pericarp glutinous rice), Hwasunchalbyeo (white pericarp glutinous rice), and Ilpumbyeo (white pericarp non-glutinous rice). Quantitative high performance liquid chromatography (HPLC) analyses showed that Jakwangchalbyeo contains the highest amount of total phenolic substances. Radical scavenging activities measured by the 1,1-diphenyl-2-picryl hydrazyl (DPPH) assay were 87.5% (Jakwangchalbyeo), 45.0% (Hwasunchalbyeo), and 50.0% (Ilpumbyeo). The results suggest a positive correlation between the phenolic content and the antioxidation capacity. Antioxidant activity in the ethanolic extract of rice grain was further assessed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay and fluorescence-activated cell sorting (FACS) analysis of H4IIE cells treated with hydrogen peroxide (H2O2). Hwasunchalbyeo and Ilpumbyeo extracts showed no significant effects on H2O2-induced oxidative stress. Jakwangchalbyeo extract increased cell viability by up to 82% and 74% after 5- and 24-h treatments at 100 μg/mL, respectively. Consistent with the results of DPPH and MTT assays, dichlorofluorescein (DCF) fluorescence was further reduced when H2O2 was applied with Jakwangchalbyeo extract. In conclusion, red pericarp Jakwangchalbyeo grain extracts exerted significantly higher inhibitory effects on H2O2-induced oxidative stress in H4IIE cells than did other white pericarp rice grain extracts.