Structure and physicochemical properties of a new variety of purple rice (Oryza sativa L. indica) starch

Food Science and Biotechnology - The investigation of the structure and physicochemical properties of starch extracted from a new variety of purple rice was the aim of this study. Starch extracted...     

Identification of anthocyanins isolated from black rice (Oryza sativa L.) and their degradation kinetics

Black rice is rich in anthocyanins-plant pigments. The aim of this work was to identify anthocyanins in black rice using high-performance liquid chromatography (HPLC)-electrospray ionization — mass spectrometry with diode array detection. Four different anthocyanins (cyanidin-3-glucoside, peonidin-3-glucoside, cyanidin-3,5-diglucoside, cyanidin-3-rutinoside) were identified in black rice. Thermal stability of the four anthocyanins in black rice extract was studied at selected temperatures (80 °C, 90 °C and 100 °C) in the range of pH 1.0–pH 6.0. The results indicated that the thermal degradation of anthocyanins followed the first-order reaction kinetics. The temperature-dependent degradation was adequately modeled on the Arrhenius equation. The calculated values of activation energies (Ea), t_1/2 and k were different for the four anthocyanins. The degradation rate of monomeric anthocyanin increased with increasing heating temperature and pH values. Especially, as heating temperature increasing to 100 °C and pH value to 5.0.     

Identification and quantification of anthocyanins from the grains of black rice (Oryza sativa L.) varieties

The purpose of this research was conducted to determine anthocyanin content from the grains of 10 Korean black rice varieties. Moreover, the primary constituents including protein and oil were evaluated. Anthocyanins, cyanidin-3-O-glucoside (1) and peonidin-3-O-glucoside (2), were isolated and elucidated using reversephase C₁₈ chromatography, nuclear magnetic resonance (NMR) spectroscopy, and high performance liquid chromatography (HPLC) with diode array detection and electrospray ionization/mass spectrometry (DAD-ESI/MS). Anthocyanin showed significant differences and cyanidin-3-O-glucoside (1) (52.1±6.3-1,601.0±8.5 μg/g) exhibited a markedly higher content than peonidin-3-O-glucoside (2) (ND-82.6±1.2 μg/g). Among varieties, ‘Heugjinjubyeo’ showed the highest anthocyanin (1: 1,601.0±8.5, 2: 82.6±1.2 μg/g), whereas ‘Heughyang’ was the lowest (1: 52.1±6.3 μg/g, 2: ND). Protein and oil exhibited the minor differences and their contents ranged from 10.7±0.0 to 14.1±0.1% and from 2.1±0.0 to 2.9±0.0%. Overall results suggest that anthocyanin can be a key factor in functional property of black rice and ‘Heugjinjubyeo’ may be very important source concerning nutritional value.     

Arsenic accumulation and metabolism in rice (Oryza sativa L.)

The use of arsenic (As) contaminated groundwater for irrigation of crops has resulted in elevated concentrations of arsenic in agricultural soils in Bangladesh, West Bengal (India), and elsewhere. Paddy rice (Oryza sativa L.) is the main agricultural crop grown in the arsenic-affected areas of Bangladesh. There is, therefore, concern regarding accumulation of arsenic in rice grown those soils. A greenhouse study was conducted to examine the effects of arsenic-contaminated irrigation water on the growth of rice and uptake and speciation of arsenic. Treatments of the greenhouse experiment consisted of two phosphate doses and seven different arsenate concentrations ranging from 0 to 8 mg of As L(-1) applied regularly throughout the 170-day post-transplantation growing period until plants were ready for harvesting. Increasing the concentration of arsenate in irrigation water significantly decreased plant height, grain yield, the number of filled grains, grain weight, and root biomass, while the arsenic concentrations in root, straw, and rice husk increased significantly. Concentrations of arsenic in rice grain did not exceed the food hygiene concentration limit (1.0 mg of As kg(-1) dry weight). The concentrations of arsenic in rice straw (up to 91.8 mg kg(-1) for the highest As treatment) were of the same order of magnitude as root arsenic concentrations (up to 107.5 mg kg(-1)), suggesting that arsenic can be readily translocated to the shoot. While not covered by food hygiene regulations, rice straw is used as cattle feed in many countries including Bangladesh. The high arsenic concentrations may have the potential for adverse health effects on the cattle and an increase of arsenic exposure in humans via the plant-animal-human pathway. Arsenic concentrations in rice plant parts except husk were not affected by application of phosphate. As the concentration of arsenic in the rice grain was low, arsenic speciation was performed only on rice straw to predict the risk associated with feeding contaminated straw to the cattle. Speciation of arsenic in tissues (using HPLC-ICP-MS) revealed that the predominant species present in straw was arsenate followed by arsenite and dimethylarsinic acid (DMAA). As DMAA is only present at low concentrations, it is unlikely this will greatly alter the toxicity of arsenic present in rice.     

Flavour production in plant cell cultures of basmati rice (Oryza sativa L)

Callus cultures of naturally flavoured rice (Oryza sativa var 370) called basmati were obtained on Murashige and Skoog medium with 2,4-dichlorophenoxyacetic acid and kinetin. There was a perceptible basmati flavour in fresh callus. The volatile flavour components of basmati rice and callus were obtained by steam distillation-solvent extraction and were analysed on GC-MS. A qualitative comparison of volatile flavour components of callus cultures and natural basmati rice was also made. The results show the presence of 29 major compounds in rice and 23 in callus. The identified compounds include hydrocarbons, ketones, aldehydes, alcohols and esters. This demonstrated the potential of callus of basmati rice for flavour development.     

Brown rice (Oryza sativa L. cv. Hiami) extract promotes cellular growth by upregulation of GH and IGF-1 expression and secretion

Food Science and Biotechnology - The effects of the ethanolic extract of brown rice (BRE, Oryza sativa L. cv. Hiami) on cellular growth were investigated. Gene expression analysis by qPCR showed...     

Grain accumulation of selenium species in rice (Oryza sativa L.)

Efficient Se biofortification programs require a thorough understanding of the accumulation and distribution of Se species within the rice grain. Therefore, the translocation of Se species to the filling grain and their spatial unloading were investigated. Se species were supplied via cut flag leaves of intact plants and excised panicle stems subjected to a ± stem-girdling treatment during grain fill. Total Se concentrations in the flag leaves and grain were quantified by inductively coupled plasma mass spectrometry. Spatial accumulation was investigated using synchrotron X-ray fluorescence microtomography. Selenomethionine (SeMet) and selenomethylcysteine (SeMeSeCys) were transported to the grain more efficiently than selenite and selenate. SeMet and SeMeSeCys were translocated exclusively via the phloem, while inorganic Se was transported via both the phloem and xylem. For SeMet- and SeMeSeCys-fed grain, Se dispersed throughout the external grain layers and into the endosperm and, for SeMeSeCys, into the embryo. Selenite was retained at the point of grain entry. These results demonstrate that the organic Se species SeMet and SeMeSeCys are rapidly loaded into the phloem and transported to the grain far more efficiently than inorganic species. Organic Se species are distributed more readily, and extensively, throughout the grain than selenite.     

The process of methylmercury accumulation in rice (Oryza sativa L.)

Recent studies have shown that rice consumption can be an important pathway of methylmercury (MeHg) exposure to humans in Hg mining areas and also in certain inland areas of Southwestern China. The seed of rice has the highest ability to accumulate MeHg compared to other tissues. The main objective of this study was to investigate the process of (MeHg) accumulation in rice seed (Oryza sativa L.) by monitoring MeHg levels in specific tissues of rice plants experiencing various levels of Hg multisource pollution during a full rice growing season. Four groups of experimental plantations were utilized, distributed among a rural artisanal Hg production site and a regional background control site. Our results suggest that the newly deposited Hg is more readily transformed to MeHg and accumulated in rice plants than Hg forms with an extended residence time in soil, and soil is the potential source of MeHg in the tissues of rice plants. MeHg in soil was first absorbed by roots and then translocated to the above-ground parts (leaf and stalk). During the full rice growing season only a very small amount of MeHg was retained in the root section. In the premature plant, the majority of MeHg is located in the leaf and stalk; however, most of this MeHg was transferred to seed during the ripening period.     

Genetic diversity in the physicochemical properties of waxy rice (Oryza sativa L) starch

The genetic diversity in the physicochemical properties of starches from 56 waxy rice (Oryza sativa L) genotypes (34 of indica and 22 of japonica) was studied. The parameters included thermal and retrogradation properties tested by differential scanning calorimetry (DSC), pasting viscosity tested by rapid viscoanalyser (RVA), and flour swelling volume (FSV). Wide diversity was found in all the parameters. According to their gelatinisation temperature (GT), the waxy rice genotypes could be divided into two groups, a high‐GT group and a low‐GT group. A total of 15 genotypes were identified as high‐GT, all belonging to the indica subspecies. There was about a 5 °C difference within each group and a 10 °C difference between groups. Many parameters were correlated with each other in all 56 waxy rices, but some correlations were also consistent and significant when comparing the high‐GT group and the low‐GT group separately. For example, hot paste viscosity (HPV) was positively correlated with onset temperature (T_o) and enthalpy of gelatinisation (ΔH_g). The results suggested that initial screening in waxy rice breeding programmes for varieties with desirable starch properties for specific food uses could be efficiently accomplished using pasting profiles from the RVA. Copyright © 2004 Society of Chemical Industry     

An optimal extraction solvent and purification adsorbent to produce anthocyanins from black rice (Oryza sativa cv. Heugjinjubyeo)

Black rice was used to produce anthocyanins, an important natural red food colorant. Integrated methods for extraction and purification of anthocyanins were investigated. Four solvents and 6 adsorbents were used for extraction and purification, respectively. Acidified 70%(v/v) ethanol resulted in the highest anthocyanin extract concentration of 461.72 mg/L. Amberlite XAD7HP had the highest adsorption capacity of 0.406±0.010 mg/g of adsorbent and desorption capacity of 0.252±0.016 mg/g of adsorbent. Acidified ethanol effectively eluted anthocyanin pigments from Amberlite XAD7HP at a concentration of 60%(v/v). Experimental adsorption data best fit to pseudosecond-order kinetic and Langmuir isotherm models. Purification parameters were optimized through dynamic adsorption/desorption experiments with Amberlite XAD7HP. The concentration of sugars (impurities) decreased from an initial 452.78 μg/mL to 169.75 μg/mL after purification.     

水稻贮藏特性与籼粳基因型的关系

实现以PCR为基础的水稻种质的耐储藏性检测,将大大加快水稻及其他粮食作物耐储藏品种的培育和推广。本研究首先使用12个籼粳特异性PCR标记对育种与生产中常用的35个籼粳稻进行基因型鉴定,然后,依据基因型信息的聚类分析,将不同籼粳基因型水稻分为籼型、偏籼型、偏粳型和粳型共4类。结果表明,籼型和偏籼型品种老化指数均小于50%,而偏粳型和粳型水稻材料则大多不耐储藏或储藏性较差,偏粳型材料较粳型材料耐储藏性好,并且储藏后粳稻的总酸变化较剧烈。利用籼粳特异性标记的籼粳基因型分析与籼粳型态指标结合可以快捷、简便而有效的鉴别特殊的耐储藏品种,为耐储藏品种筛选与育种提供基础。     

Effects of different storage conditions on the metabolite and microbial profiles of white rice (Oryza sativa L.)

Food Science and Biotechnology - Microbial populations in white rice (Oryza sativa L.) samples stored for 6 months in open or closed conditions were studied and their metabolite profiles...     

Progress and challenges in improving the nutritional quality of rice (Oryza sativa L.)

Rice is a staple food for more than 3 billion people in more than 100 countries of the world but ironically it is deficient in many bioavailable vitamins, minerals, essential amino- and fatty-acids and phytochemicals that prevent chronic diseases like type 2 diabetes, heart disease, cancers, and obesity. To enhance the nutritional and other quality aspects of rice, a better understanding of the regulation of the processes involved in the synthesis, uptake, transport, and metabolism of macro-(starch, seed storage protein and lipid) and micronutrients (vitamins, minerals and phytochemicals) is required. With the publication of high quality genomic sequence of rice, significant progress has been made in identification, isolation, and characterization of novel genes and their regulation for the nutritional and quality enhancement of rice. During the last decade, numerous efforts have been made to refine the nutritional and other quality traits either by using the traditional breeding with high through put technologies such as marker assisted selection and breeding, or by adopting the transgenic approach. A significant improvement in vitamins (A, folate, and E), mineral (iron), essential amino acid (lysine), and flavonoids levels has been achieved in the edible part of rice, i.e., endosperm (biofortification) to meet the daily dietary allowance. However, studies on bioavailability and allergenicity on biofortified rice are still required. Despite the numerous efforts, the commercialization of biofortified rice has not yet been achieved. The present review summarizes the progress and challenges of genetic engineering and/or metabolic engineering technologies to improve rice grain quality, and presents the future prospects in developing nutrient dense rice to save the everincreasing population, that depends solely on rice as the staple food, from widespread nutritional deficiencies.     

In situ regeneration of rice (Oryza sativa L.) callus immobilized in polyurethane foam

An in situ regeneration system for rice calli comprised of a callus growth stage and two regeneration stages was developed. After the first stage of regeneration, the medium is changed and the calli are immobilized in polyurethane foam supports, in each of which 3-5 regenerated plantlets develop from the immobilized calli during the second stage. While no significant change in callus size was observed during the first stage of regeneration, in the second stage callus enlargement and shoot regeneration predominated. In the light of these findings, calli were immobilized in the second stage after medium exchange. The use of 10-mm support cubes with an average pore size of 3.6 mm resulted in the most efficient immobilization and in situ regeneration. Medium exchange after 15 d gave the largest number of support cubes with shoots. When rice calli were cultivated in support cubes placed in 60 ml second-stage medium in a 500-ml flask, the immobilization ratio was 83%, and 82% of the support cubes contained 3-5 regenerated plantlets after 25 d. The shoot lengths of the regenerated plantlets obtained from the in situ regeneration culture were longer than those from a suspension culture. When support cubes with 3-5 regenerated plantlets were transferred from the flask to 1 4 MS solid medium supplemented with 10 g/l sorbitol and 5 g/l sucrose, the regenerated plantlets developed quickly into plants with a length above 10 cm after 10 d.     

Effects of microwaves on the reduction of Aspergillus flavus and Aspergillus parasiticus on brown rice (Oryza sativa L.) and barley (Hordeum vulgare L.)

ABSTRACT

Aspergillus flavus and Aspergillus parasiticus are primary pathogen moulds on brown rice and barley. This study investigated the effects of microwave irradiation (MWI) (2450 MHz, 700 W, 10–50 s) on inactivation of A. flavus and A. parasiticus on brown rice and barley and the quality of these samples. The counts of both strains were significantly (p < 0.05) reduced by the stepwise increase in MWI treatment time. The log reductions of A. flavus on brown rice and barley were 0.05 and 0.04 after 10 s; 1.06 and 1.05 after 20 s; 1.59 and 1.52 after 30 s; and 3.04 and 2.78 after 40 s. The log reductions of A. parasiticus on brown rice and barley were 0.06 and 0.10 after 10 s; 1.20 and 1.00 after 20 s; 2.04 and 1.61 after 30 s; and 2.89 and 2.90 after 40 s. Moreover, neither strain survived after 50 s of MWI. The Hunter colour ‘L’ gradually increased with increasing MWI treatment time. However, there were no significant differences in the ‘L’ of brown rice after 10–40 s of MWI treatment and of barley after 10–30 s of MWI treatment. The Hunter colour ‘a’ and ‘b’ gradually increased with increasing microwave time. No significant change was observed in the moisture content of either cereal treated with 10–20 s of MWI. The differences in the sensory quality (colour, appearance, flavour, texture and overall acceptability) after 0–30 s of MWI were not significant. However, values for colour, appearance, texture and overall acceptability were significantly reduced when treated with 40–50 s of MWI. Therefore, with 20 s of MWI at 2450 MHz, 700 W could be effective for > 90% reduction of mould without causing deleterious changes to the colour, moisture content and sensory qualities of these cereals.     

Duplex real-time PCR for the determination of non-Basmati rice in Basmati rice (Oryza sativa)

Basmati rice has a higher trade value compared to other rice varieties. Adulterations of Basmati with cheaper varieties, sometimes in substantially amounts, are well known. To screen Basmati samples for such fraud, an efficient duplex real-time PCR assay was developed. It applies a mixed technique using hydrolysis probes in conjunction with Plexor? technology. This assay is a cost-effective system to screen for non-Basmati contents in the range of 1 % or higher. It is cheaper and less time consuming than microsatellite analysis which is the conventional method applied, and comparing the two methods reveals good correlation.