Effect of parboiling and bran removal on aflatoxin levels in Sri Lankan rice

Commercial parboiling of rice in Sri Lanka and many south Asian countries provides ideal conditions for the occurrence of aflatoxins because the rice is steeped (allowing fermentation) thus providing ideal conditions for growth of toxigenic Aspergillus species. However the traditional cottage method of parboiling rice, which does not involve steeping, appears to reduce Aspergillus growth even after long storage periods. Preferential infection of parboiled rice by Aspergillus flavus was observed. Aflatoxin contents in inoculated rice produced by commercial parboiling (AFB₁ 60–92 mg/kg) were significantly higher than that in inoculated cottage processed rice (AFB₁ 12–29 g/kg). The steeping (precooking/ soaking) process in commercial parboiling appears to increase the susceptibility of rice grains to fungal infection. Aflatoxin content in grains increased considerably with the increase in duration of soaking. However, the addition of 10 ppm calcium hypochlorite (bleach) to soaking water appreciably reduced A. flavus contamination and subsequent aflatoxin content in parboiled rice. No significant reduction in aflatoxin levels were observed after bran removal of contaminated rice.     

Fractionation of the rice bran layer and quantification of vitamin E, oryzanol, protein, and rice bran saccharide

Value-added processing with respect to rice milling has traditionally treated the rice bran layer as a homogenous material that contains significant concentrations of high-value components of interest for pharmaceutical and nutraceutical applications. Investigators have shown that high-value components in the rice bran layer vary from differences in kernel-thickness, bran fraction, rice variety, and environmental conditions during the growing season. The objectives of this study were to quantify the amount of rice bran removed at pre-selected milling times and to correlate the amount of rice bran removed at each milling time with the concentration of vitamin E, gamma-oryzanol, rice bran saccharide, and protein obtained. The ultimate goal of this research is to show that rice bran fractionation is a useful method to obtain targeted, nutrient-rich bran samples for value-added processing. Two long grain rice cultivars, Cheniere and Cypress, were milled at discrete times between 3 and 40 seconds using a McGill mill to obtain bran samples for analysis. Results showed that the highest oryzanol and protein concentrations were found in the outer portion of the rice bran layer, while the highest rice bran saccharide concentration was found in the inner portion of the bran layer. Vitamin E concentration showed no significant difference across the bran layer within a variety, though the highest magnitude of concentration occurs within the first 10 seconds of milling for both varieties. To extract the higher concentration of oryzanol and protein only the outer portion of the bran layer requires processing, while to extract the higher concentration of rice bran saccharide, only the inner portion of the bran layer requires processing. Rice bran fractionation allows for the selective use of portions of the bran layer and is advantageous for two reasons: (1) bran fractions contain higher concentrations of components of interest with respect to the overall bran layer average, and (2) less bran needs to be processed to obtain components of interest.     

Potential pathogenicity of Cladosporium tennuisimum,Phaeoisaria clematidis and Ramichloridium subulatum in a mouse model

In Sri Lanka, rice is the main staple which is mostly processed into parboiled rice. The levels of aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁) in parboiled and raw milled rice collected from major rice producing areas and rice consuming townships were estimated. In almost all the samples of parboiled rice examined, the AFB₁ and AFG₁ contents were significantly higher than in raw milled rice. The highest AFB₁ content was 185 µg/kg and AFG₁ content 963 g/kg. These samples were collected from a major rice producing/milling district where the mean relative humidity is 78% and mean annual temperature 27 °C which is the highest amongst the rice growing areas in Sri Lanka. Raw rice was either free of aflatoxins or when toxins were detected, they occurred in less than 10% of the samples. The frequency of occurrence of surface fungal flora (Aspergillus/Penicillium) and aflatoxin content in market samples was closely related. Brownish or greenish moldy rice samples with fermented odour contained over 1000 g/kg of AFB₁.     

Changes in moisture content,mycoflora and aflatoxin content of rice bran during storage

The changes in moisture content, storage mycoflora and aflatoxin B₁ (AFB₁) in bran from untreated or raw rice (Rr) and parboiled rice (Pbr) stored in small lots in polyethylene bags were studied at 15-day intervals up to 60 days, using five lots of each type of bran. Deterioration was more rapid with reference to all the three parameters, in Rr bran compared to Pbr bran, the former becoming completely overgrown and caked with fungi by the end of 60 days.Aspergillus flavus was the dominant fungus in Pbr bran, whereasA. candidus andTrichoderma viride were abundant in Rr bran. The frequency of incidence as well as concentration of AFB₁ increased with storage time in both types of bran, but the rate of increase as well as overall concentration were much higher in Rr bran. Thus raw rice bran is unsuitable for prolonged storage.Abbreviations AFB₁ aflatoxin B₁ - MC moisture content - Pbr parboiled rice - Rr raw rice     

QTL mapping of grain quality traits from the interspecific cross <Emphasis Type="Italic">Oryza sativa</Emphasis> × <Emphasis Type="Italic">O. glaberrima</Emphasis>

International rice export markets are increasing demands for rapid improvements in grain quality characteristics. The African rice Oryza glaberrima is a new potential source of genes that will enhance the eating, cooking, and milling properties of the rice grain. The objective of this research was to identify and characterize quantitative trait loci (QTLs) among 312 doubled haploid lines derived from the BC₃F₁ of an interspecific cross of O. sativa × O. glaberrima. Genetic material was planted in replicated plots and evaluated for ten grain quality traits in 2001 in Colombia. A linkage map was constructed with 100 polymorphic microsatellite markers using the mapdisto software program to adjust for segregation distortion. Transgressive segregation was observed for all traits. Interval and composite interval analyses identified 27 QTLs for nine characters located on 11/12 chromosomes. The chromosomal positions of QTLs for percentage amylose, alkali-spreading score, and percentage protein were in agreement with data reported by others, whereas QTL markers for percentage head rice, percentage milled rice, percentage protein, and percentage brown rice were different in our mapping population. Five major QTLs were found to be associated with improved percentage rice bran, percentage amylose, and alkali-spreading score. Seven QTLs for improved percentage rice bran, percentage milled rice, alkali-spreading score, percentage protein, and grain length/width ratio were derived from the O. glaberrima accession. Three new QTLs for percentage rice bran are reported here for the first time. Results from this study suggest that the African rice might be a valuable new source for introgression and improvement of several traits that affect quality traits demanded by the different rice export markets.Approved for publication by the Director of the Louisiana Agricultural Experiment Station as paper no. 04-14-0054.     

Properties of Whole and Undigested Fraction of Protein Bodies of Milled Rice

Protein bodies (PB) were prepared from IR480-5-9 (10.5% protein) milled rice by destarching the cooked rice flour with crystalline bacterial α-amylase. Corresponding PB from raw rice prepared by treatment with analytical grade glucoamylase were more susceptible to pepsin digestion than PB from cooked rice. The undigested residue from pepsin digestion of both cooked and raw rice PB and preparations of fecal protein particles from man and rat on an IR480-5-9 cooked milled rice diet represented the core of PB. The core protein was poorer in lysine and had lower mol. wt. subunits than whole PB protein. The pepsin-digested PB preparations had higher fat content than whole PB preparation.     

Microbiological evaluation of processed rice consumed in Japan

Samples of processed rice from four different brands showed counts of mesophilic aerobic bacteria from 1 × 10² to 5 × 10³ for milled rice and from 1 × 10⁶ to 6.8 × 10⁶ cells g^–1 for brown rice. Rice seeds contaminated by milling had extensive counts including faecal coliforms. In cooked rice, no microbial growth was noted during 4 days at room temperature (spring season, 15–20 °C) and at least 2 weeks at 4 °C. No contamination was detected in cooked rice packs. A rapid and highly reliable procedure for detection of microorganisms in cooked rice is proposed.     

Effect of pretreatments of three waste residues,wheat straw,corncobs and barley husks on dye adsorption

The removal of dyes (Cibacron Yellow C-2R, Cibacron Red C-2G, Cibacron Blue C-R, Remazol Black B and Remazol Red RB) from an aqueous solution has been discussed by adsorption which was examined on three different low cost pretreated agricultural residues viz., wheat straw, corncob and barley husk. The pretreatments were carried out in order to delignify, or to increase the surface area of the sorbents, and to study their effect on the rate and effective adsorption of dyes. Steam, alkali, ammonia steeping and milling were the pretreatments employed and compared with the untreated sorbents. A higher percentage of dye removal was achieved at a faster rate by the milled samples proving milling to be a better and more cost effective treatment, except for barley husk which had a higher percentage removal for the control.     

水稻米粒延伸性的遗传剖析

以籼稻ZYQ8与粳稻JX17为亲本的DH群体作为研究材料,考察DH群体及双亲的米粒延伸率相关性状,并使用该群体的分子连锁图谱进行QTL分析.共检测到14个与稻米延伸性有关的QTL,包括2个粒长QTL、7个饭粒长QTL和5个米粒延伸率QTL,分别位于第1、2、3、5、6、7、10、11和12染色体.所有QTL的LOD值介于2.26～9.25,分别解释性状变异的5.31%～17.21%.在第3染色体上的G249～G164、第6染色体上的G30～RZ516和第10染色体上的G1082～GA223区间同时检测到控制饭粒长和米粒延伸率的QTL.米粒延伸性受多基因控制,Wx基因与位于第6染色体上的qCRE-6的G30～RZ516区间相近,对米饭的延伸性具重要影响.     

Wet disk milling pretreatment without sulfuric acid for enzymatic hydrolysis of rice straw

Rice straw has recently attracted interest in Japan as a potential source of raw material for ethanol production. Wet disk milling, a continuous pretreatment to enhance the enzymatic digestibility of rice straw, was compared with conventional ball milling and hot-compressed water treatment. Pretreated rice straw was evaluated by enzymatic hydrolysis using Acremonium cellulase and characterized by X-ray diffraction and scanning electron microscopy. Glucose and xylose yields by wet disk milling, ball milling, and hot-compressed water treatment were 78.5% and 41.5%, 89.4% and 54.3%, and 70.3% and 88.6%, respectively. Wet disk milling and hot-compressed water treatment increased sugar yields without decreasing their crystallinity. The feature size of the wet disk milled rice straw was similar to that of hot-compressed water-treated rice straw. The energy consumption of wet disk milling was lower than that of other pretreatments. Thus, wet disk milling is an economical, practical pretreatment for the enzymatic hydrolysis of lignocellulosic biomass, especially herbaceous biomass such as rice straw.     

Residue Dynamics and Persistence of Aldicarb and Its Biologically Similar Active Metabolites in Grapevines

Residue dynamics in giapevine of the nematicide aldicarb (2-methyl-(metbylthio) propionaldehyde-O-(Methylcarbamoyl) oxime) and its biologically similar active metabolites, aldicarb sulfoxide and aldicarb sulfone, were determined by gas chromatographic techniques. Residues were found in the roots, trunks, stems, and leaves of grapevine 120 d after application. Residues in leaves as high as 1.40 and 8.89 ppm resulted from 4.5 and 9 kg ai/ha respectively. In roots, trunks, and stems the residues had also declined after 180 d. No residues were detected in the newly forming immature fruit. Residues in roots, trunks, young branches, and leaves declined further after 270 d, but residues in mature fruit at harvest time were 0.03 and 0.05 ppm from application of 4.5 and 9 kg ai/ha, respectively. In other trials the amount of aldicarb toxic residues found in mature fruit at harvest time varied with grape varieties, time and rate of application, total amount of rainfall, irrigation water, and soil type.     

Analysis of Metal Element Distributions in Rice (Oryza sativa L.) Seeds and Relocation during Germination Based on X-Ray Fluorescence Imaging of Zn,Fe, K,Ca, and Mn

Knowledge of mineral localization within rice grains is important for understanding the role of different elements in seed development, as well as for facilitating biofortification of seed micronutrients in order to enhance seeds’ values in human diets. In this study, the concentrations of minerals in whole rice grains, hulls, brown rice, bran and polished rice were quantified by inductively coupled plasma mass spectroscopy. The in vivo mineral distribution patterns in rice grains and shifts in those distribution patterns during progressive stages of germination were analyzed by synchrotron X-ray microfluorescence. The results showed that half of the total Zn, two thirds of the total Fe, and most of the total K, Ca and Mn were removed by the milling process if the hull and bran were thoroughly polished. Concentrations of all elements were high in the embryo regions even though the local distributions within the embryo varied between elements. Mobilization of the minerals from specific seed locations during germination was also element-specific. High mobilization of K and Ca from grains to growing roots and leaf primordia was observed; the flux of Zn to these expanding tissues was somewhat less than that of K and Ca; the mobilization of Mn or Fe was relatively low, at least during the first few days of germination.     

Effect of cleaning, milling, and baking on deoxynivalenol in wheat

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.     

Effect of cleaning, milling, and baking on deoxynivalenol in wheat.

Samples of wheat naturally infected by Fusarium graminearum Schwabe were obtained from mills in Oklahoma, Missouri, Kansas, and Minnesota and fields in Nebraska and Kansas in 1982; they were analyzed for deoxynivalenol (DON). The wheat was milled, and DON was found throughout all the milling fractions (bran, shorts, reduction flour, and break flour). The DON recoveries for each mill run ranged from 90 to 98%. These samples, regardless of DON concentration, also gave similar fractional distributions of DON. The greatest (21 ppm [21 micrograms/g]) concentration of DON was found in the bran, and the smallest (1 ppm) was found in the break flour. Cleaning and milling were not effective in removing DON; DON was not destroyed in the bread baked from the naturally contaminated whole wheat flour, but the effect on its concentration in the samples analyzed varied, the reduction ranging from 19 to 69%. The percent reduction found in the cleaned wheat ranged from 6 to 19%. DON concentrations in the following commercially made breads, caraway rye, seedless rye, and pumpernickel, were 45 ppb (ng/g), 39 ppb, and 0 ppb, respectively. The limits of detection by gas chromatography-mass spectrometry and high-pressure liquid chromatography for DON were 0.5 and 10 ng, respectively.     

Wet‐milling transgenic maize seed for fraction enrichment of recombinant subunit vaccine

The production of recombinant proteins in plants continues to be of great interest for prospective large‐scale manufacturing of industrial enzymes, nutrition products, and vaccines. This work describes fractionation by wet‐milling of transgenic maize expressing the B subunit of the heat‐labile enterotoxin of Escherichia coli (LT‐B), a potent immunogen and candidate for oral vaccine and vaccine components. The LT‐B gene was directed to express in seed by an endosperm specific promoter. Two steeping treatments, traditional steeping (TS, 0.2% SO₂ + 0.5% lactic acid) and water steeping (WS, water only), were evaluated to determine effects on recovery of functional LT‐B in wet‐milled fractions. The overall recovery of the LT‐B protein from WS treatment was 1.5‐fold greater than that from TS treatment. In both steeping types, LT‐B was distributed similarly among the fractions, resulting in enrichment of functional LT‐B in fine fiber, coarse fiber and pericarp fractions by concentration factors of 1.5 to 8 relative to the whole kernels on a per‐mass basis. Combined with endosperm‐specific expression and secretory pathway targeting, wet‐milling enables enrichment of high‐value recombinant proteins in low‐value fractions, such as the fine fiber, and co‐utilization of remaining fractions in alternative industrial applications. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010     

Rice bran stabilization and rice bran oil extraction using ohmic heating

Ohmic heating has been shown to increase the extraction yields of sucrose from sugar beets, apple juice from apples, beet dye from beet root, and soymilk from soybeans. Rice bran is a byproduct of the rice milling process that has economic potential by virtue of highly nutritious rice bran oil contained within the bran. In this study, ohmic heating was used to stabilize rice bran and to improve rice bran oil extraction yield as compared to microwave heating and a control (no heating). Results showed that ohmic heating is an effective method for rice bran stabilization with moisture addition. Free fatty acid concentration increased more slowly than the control for raw bran samples subjected to ohmic heating with no corresponding temperature rise, indicating that electricity has a non-thermal effect on lipase activity. Ohmic heating increased the total percent of lipids extracted from rice bran to a maximum of 92%, while 53% of total lipids were extracted from the control samples. Lowering the frequency of alternating current significantly increased the amount of oil extracted, probably due to electroporation. Ohmic heating was successfully applied to rice bran despite its high oil content. This could have important implications for the enhanced extraction of non-polar constituents.     

Natural occurrence of toxigenic fungi and mycotoxins in rice bran

Thirty four samples of rice bran, of which 9 were from raw (untreated) rice (RR) and 25 from parboiled rice (PbR) were collected from commercial rice mills in and around Madras and analysed for storage mycoflora and mycotoxins. Fungi of the Aspergillus flavus group were present in 29 of the 34 samples (8 from RR and 21 from PbR) in quantities ranging from <1–432 thousand propagules/g, though not always as the dominant mycoflora. Fungal numbers were usually higher in RR than in PbR samples.Five of the 9 RR samples and 6 of the 25 PbR samples were positive for aflatoxins. Among 29 isolates of A. flavus obtained from the bran samples, 16 isolates –6 from RR bran and 10 from PbR bran — were found to be toxigenic in vitro. Some isolates of A. candidus also seemed to produce aflatoxin and other fluorescent substances.     

Effects of stabilized rice bran, its soluble and fiber fractions on blood glucose levels and serum lipid parameters in humans with diabetes mellitus Types I and II

Stabilized rice bran (SRB), a source of complex carbohydrates, tocols, gamma-oryzanols, and polyphenols, was treated with carbohydrases and heat to yield two fractions, rice bran water solubles (RBWS), and rice bran fiber concentrates (RBFC). Stabilized rice bran and its fractions were fed for 60 days to insulin-dependent and noninsulin-dependent diabetes mellitus (IDDM = Type I and NIDDM = Type II) subjects to determine possible effects on serum hemoglobin, carbohydrate and lipid parameters. The Type I subjects (n = 22, 26, and 20) fed Stabilized rice bran, rice bran water solubles, and rice bran fiber concentrates plus AHA Step-1 diet reduced glycosylated hemoglobin 1%, 11%, and 10%, respectively. The fasting serum glucose levels were also reduced significantly (P < 0.01) with stabilized rice bran (9%), rice bran water solubles (29%), and rice bran fiber concentrates (19%).The Type II subjects (n = 31, and 26) fed rice bran water solubles and rice bran fiber concentrates plus AHA Step-1 diet had decreased levels of glycosylated hemoglobin (15% and 11%) and fasting glucose (33% and 22%; P < 0.001), respectively. Serum insulin levels were increased (4%) with rice bran water solubles in both types of diabetes. The reduction of glycosylated hemoglobin and a slight increase in insulin levels indicate that consumption of rice bran water solubles can control blood glucose levels in human diabetes. Serum total cholesterol, LDL-cholesterol, apolipoprotein B, and triglycerides levels were reduced with rice bran fiber concentrates in the Type I (10, 16, 10, 7%) and Type II groups (12, 15, 10, 8%), respectively. These results indicate that rice bran water solubles significantly reduces hyperglycemia (P < 0.01), whereas rice bran fiber concentrates reduces hyperlipidemia (P < 0.05) in both types of diabetes. Therefore, these natural products can be used as nutritional supplements for the control of both types of diabetes mellitus in humans.     

稻鸭共生有机栽培模式对黄河三角洲稻米品质的影响

在黄河三角洲地区设计稻鸭共生、人工除草、常规稻作3种栽培模式,研究其对稻米加工品质、外观品质、蒸煮和食味品质、卫生品质的影响.结果表明:与常规稻作相比,稻鸭共生可以增加水稻粒宽,提高糙米率、精米率、整精米率,减少垩白,这主要是由于有效穗数和籽粒重的提高以及弱势粒的降低所致.稻鸭共生和人工除草栽培模式可以增加胶稠度,降低直连淀粉和蛋白质含量,改善稻米食味性,这主要归功于有机肥的施用.由于生产过程不施用化学肥料和农药,稻鸭共生、人工除草模式可以大幅降低甚至检测不到农药残留.稻鸭共生既可改善稻米品质,又能保护环境,为优质水稻生产提供了一条较好的生态技术途径.     

浙江省早籼稻区试品种（系）碾磨品质研究

本文对水稻区域试验中多品种（系）、多年、非平衡、无重复分析值的品质性状资料提出相应的统计分析方法,并对早籼稻区试品种（系）碾磨品质作了统计分析．分析结果表明,91—94年期间参试的早籼稻品种（系）其糙米率、精米率较“七五”期间参试的品种（系）有显著提高,金89—1、中选2号、浙733品种（系）的糙米率、精米率都显著或极显著的高于对照品种．三个碾磨品质中整精米率的方差较大,且变异主要来自于品种×年份的交互作用．