White Rice Varieties Research Articles

Unraveling the nutritional and therapeutic properties of ‘Kavuni’ a traditional rice variety of Tamil Nadu

‘Kavuni’ a traditional brownish black rice variety is known for its anti-diabetic properties and is grown under limited areas of Tamil Nadu, India. The present study was aimed at profiling the nutritional and therapeutic values of Kavuni grains in comparison with three other popularly eaten white rice varieties of Tamil Nadu viz., CO 50, IR64 and White Ponni. Biochemical analysis revealed the significant differences in the nutritional composition of Kavuni grains when compared to other three white rice genotypes viz., 29–35 % reduced level of total soluble sugars, low fat content (8–35 %), 21–52 % increased dietary fibre and 7–24 % increased total protein content. Kavuni grains had significantly higher amount of iron (20–30 %), calcium (33–45 %), copper (9.5–14.7 %), sodium (21–38 %), potassium (7–15 %) and magnesium (8.9–26 %). GC-MS analysis showed that phenolic acids and flavonoids were predominant in the Kavuni grains whereas sugars and fatty acids were predominant in the grains of a white rice variety CO 50. Further, Kavuni was found to possess significantly higher levels of different carotenoids (β-carotene—46.2 μg/100 g; lutein—221.6 μg/100 g), total phenolics (28.8 μg/100 g) and higher anti-oxidant activity. Methanol and ethyl acetate extracts of Kavuni grains were found to exhibit significantly higher level of inhibitory activity against α-amylase and α-glucosidase than the extracts of CO 50 (α-amylase IC50—0.1, 1.0 μg/ml and α-glucosidase IC50 0.04, 0.05 μg/ml).

Heavy metals in Australian grown and imported rice and vegetables on sale in Australia: Health hazard

Dietary exposure to heavy metals is a matter of concern for human health risk through the consumption of rice, vegetables and other major foodstuffs. In the present study, we investigated concentrations of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in Australian grown and imported rice and vegetables on sale in Australia. The mean concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn in Australian grown rice were 7.5 µg kg(-1), 21 µg kg(-1), 144 µg kg(-1), 2.9 mg kg(-1), 24.4 mg kg(-1), 166 µg kg(-1), 375 µg kg(-1), and 17.1 mg kg(-1) dry weight (d. wt.), respectively. Except Cd, heavy metal concentrations in Australian grown rice were higher than Bangladeshi rice on sale in Australia. However, the concentrations of Cd, Cr, Cu, and Ni in Indian rice on sale in Australia were higher than Australian grown rice. The concentrations of Cu and Ni in Vietnamese rice, and that of Cd, Cr, Cu, Ni, and Pb in Thai rice on sale in Australia were also higher than Australian grown rice. Heavy metal concentrations in Pakistani rice on sale in Australia were substantially lower than that in Australian grown rice. In Australian grown rice varieties, the concentrations of heavy metals were considerably higher in brown rice varieties than white rice varieties, indicating Australian brown rice as a potential source of dietary heavy metals for Australian consumers. The mean concentrations of heavy metals in Australian grown and Bangladeshi vegetables on sale in Australia were also determined. Some of the Australian grown and Bangladeshi vegetables contained heavy metals higher than Australian standard maximum limits indicating them as potential sources of dietary heavy metals for Australian consumers. Further investigation is required to estimate health risks of heavy metals from rice and vegetables consumption for Australian consumers.

Antioxidant, anti-amylase and anti-glycation potential of brans of some Sri Lankan traditional and improved rice (Oryza sativa L.) varieties

Abstract Brans of 23 traditional and 12 improved (both red and white) rice varieties in Sri Lanka were screened for anti-amylase and anti-glycation activities in vitro . Varieties which showed the highest inhibitory activities at screening were further investigated for anti-glucosidase and glycation reversing as anti-diabetic properties. The same varieties were studied for selected antioxidant properties. Significantly high anti-amylase and anti-glycation activities were observed for bran extracts of red varieties compared to white varieties at screening. Traditional red rice varieties, Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti, exhibited significant and dose dependent anti-amylase, anti-glycation and glycation reversing activities. These varieties also showed marked antioxidant properties. It is concluded that brans of Sri Lankan traditional red rice varieties Masuran, Sudu Heeneti, Dik Wee and Goda Heeneti may be potential food supplements for diabetes.

Effect of variety and cooking method on resistant starch content of white rice and subsequent postprandial glucose response and appetite in humans.

Rice is a staple carbohydrate throughout much of the world. Previous work indicated that resistant starch (RS) content of rice consumed in India varied with rice variety and cooking method. This study quantified RS in 4 white rice varieties (jasmine, long grain, medium grain, and short grain) cooked in three manners (oven baked, conventional rice cooker, and pressure cooker), and analyzed for RS content immediately after preparation or after 3 days of refrigeration at 4°C. The rice varieties with the highest and lowest RS content were selected for a pilot- scale trial to characterize postprandial glycemic response and appetite ratings in healthy adults (n=21). Refrigerated long-grain rice cooked in a conventional rice cooker had the highest RS content (HRS, 2.55 g RS/100 g) and refrigerated short-grain rice cooked in a pressure cooker had the lowest RS content (LRS, 0.20 g RS/100 g). These rice samples were served reheated in the clinical trial. Glucose area under the curve (AUC) were significantly lower with HRS and LRS compared to glucose beverage; however, there was no difference between HRS and LRS. Glycemic indices did not differ significantly between HRS and LRS. Subjects reported an overall increased feeling of fullness and decreased desire to eat based on incremental area under the curve (iAUC) for both HRS and LRS compared to control. This study found that RS naturally occurring in rice had minimal impact on the postprandial glycemic response and appetite.

Fourier Transform Infrared Spectroscopy for Antioxidant Capacity Determination in Colored Glutinous Rice

The determination of total phenolic content and antioxidant capacity of 48 colored rice varieties and two white rice varieties from Thailand by Fourier transform infrared (FT-IR) spectroscopy (400–4,000 cm−1) was performed to explore the possibility of using FT-IR as an effective alternative technique for such determination. The peak at 1,635 cm−1 resulted from the ring C-C stretch of phenyl was clearly observed. The levels of phenolic content in rice samples as indicated with infrared spectrum were consistent with the results from chemical assays. Dark glutinous rice had the highest level of antioxidant capacity and phytochemicals followed by red rice, brown rice, and white rice. The hierarchical cluster analysis based on selected principal components from principal component analysis model was performed to produce dendrograms which discriminated rice varieties according to their color well. The partial least squares regression models were constructed, and validated models were used to predict total antioxidant capacity and total phenolic content of the rice varieties. Satisfactory precision of prediction was achieved. With technical advantages that FT-IR offers especially when large number of samples are to be analyzed, FT-IR spectral features with chemometrics are suggested to be applicable for quantification and prediction of antioxidant capacity and phenolic compound content of colored rice.

An overview of the role of rice in the UK diet

SummaryRice is a staple food for over half of the world's population. Eighty percent of the British population buy rice, predominantly white rice, with the average person consuming approximately 5.6 kg per year. Rice consumption in the UK is expected to increase slightly, as a result of the growing ethnic population and food diversification. Starchy foods such as rice, potatoes, bread and cereals are our main source of carbohydrate and play an important role in a healthy diet. As well as providing energy, rice contains other essential nutrients such as thiamine, riboflavin, niacin, vitamin E, zinc, potassium, iron and fibre. On cooking, rice swells to at least three times its original weight and therefore benefits from a low‐energy density compared to other starchy carbohydrate foods (e.g. bread), as well as a low‐sodium content (unless salt is added to rice products). It has a low allergenicity and is relatively easy to digest, making it a useful food for early weaning or during convalescence.The Department of Health encourage the selection of wholegrain versions of starchy carbohydrate foods as these are higher in fibre. Brown rice also has a higher proportion of important bioactive phytochemicals such as hemicelluloses and lignans with antioxidant and anti‐inflammatory properties that may benefit health.Despite the common perception that starchy carbohydrate foods are ‘fattening’, diets containing rice have been shown to achieve weight loss in obese subjects, although greater weight reduction has been shown with mixed rice compared with white rice. Although the reported glycaemic index (GI) of different rice varieties is inconsistent, most types of rice are classified as low or medium ‘GI’ foods but this is influenced by cooking time, the degree of gelatinisation and rice type. While there are numerous studies that have examined the link between high‐carbohydrate intakes and risk of chronic diseases such as obesity, type 2 diabetes and cardiovascular disease, relatively few have investigated the role of rice specifically, particularly in western populations. In Asian populations in whom rice is a staple food, higher white rice consumption has been associated with elevated risk of diabetes and metabolic syndrome. Some prospective cohort studies in the US have linked regular consumption of white rice with higher risk of type 2 diabetes, whereas brown rice intake was associated with lower risk. These studies were however observational in nature and so cannot determine a ‘cause and effect’ relationship, whilst their findings may be subject to residual confounding. Future studies should consider potential differences of white rice varieties, which vary in amylose content, as well as the effect of processing methods.

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

Rice grains rich in gamma-aminobutyric acid (GABA) are increasing in popularity, particularly in the health food market. GABA levels in rice are influenced by many factors, including the duration of incubation of seeds, particularly in pre-germinated brown rice grains. In this report, five different incubation durations (0, 12, 24, 36, and 48 h) and 21 rice varieties (11 landraces purple rice and 10 modern white varieties) were tested. Results show that GABA content increased steadily from 3.96 mg/100 g dry matter at 0 h duration (i.e., no incubation period) to 10.04 mg/100 g dry matter after 12 h, reaching the highest levels of 17.87 mg/100 g dry matter at 24 h incubation, and then decreased continuously afterwards to 9.91 and 1.36 mg/100 g dry matter at 36 and 48 h, respectively. A correlation of GABA levels at 0 h and 24 h was detected (r = 0.48). Genotypic variation was detected from a minimum of 6.50 to a maximum of 10.10 mg/100 g dry matter, with a mean of 8.03. At 24 h, the white rice variety KDML 105 and the purple rice variety Kum Doi Saket (23.48 and 23.63 mg/100 g dry matter, respectively) exhibited the highest GABA content of all 21 rice varieties. This indicates the importance of the local purple rice cultivars for adding nutritional value to functional food products.

A Comparative Study on the Physicochemical Characteristics of Black Rice Varieties

Physicochemical properties of black rice (Dragon eyeball 100, Heukjinjubyeo, Heukgwangbyeo, Heuknambyeo, and Josaengheukchal) and white rice (Hwayoungbyeo) varieties were investigated. Morphological properties slightly differ among the rice samples analyzed. Black rice varieties showed a higher amount of minerals, faster hydrolysis rate, and lower blue value than the ordinary white rice. High amino acid and sugar contents were found in Heuknambyeo and Heukgwangbyeo varieties, respectively. Lower oleic acid, but higher linoleic acid, was observed in Dragon eyeball 100 and Heukjinjubyeo compared with the other samples. Likewise, the pasting and viscosity values were generally higher in Heuknambyeo and Heukgwangbyeo, while lowest in Josaengheukchal. No substantial difference in X-ray diffraction pattern was observed among the samples. This study illustrates the wide variation in the physicochemical properties of the black rice varieties analyzed. The results could serve as baseline information for food processors in evaluating the quality of black rice suitable for specialty food processing.

PHYSICO-CHEMICAL AND TECHNOLOGICAL STUDIES ON SOME EGYPTIAN RICE VARIETIES

The present study was carried out to evaluate different varieties of rice (Black, Sakha 105 and Egyptian Yasmen) as brown and white rice physically, chemically and technologicaly as well as to investigate the possibility of using their rice flour as substitution materials of wheat flour in preparing biscuits. The obtained results revealed that, physical properties of paddy, brown and white rice varied from one variety to another. It was found that E. yasmine had the longest length when compared with other varieties. It had also the lowest width among all of the tested ones, whereas Sakha 105 had the highest value in grain index. The paddy rice of raw E. yasmine had the highest percentages of broken kernels and the lowest percentages of head and white rice as compared with other rice varieties. Water uptake of white rice was significantly higher than that of brown rice. Brown black rice had the longest cooking time (38 min) compared to the others. Gel consistency (GC) varied significantly between varieties in both brown and white rice. Alkali spreading value in brown rice varieties showed lower values in comparing with white rice varieties. Black rice had the highest amylase content and the lowest pasting characteristics values than those of Sakha 105. Furthermore, Black rice contains high content of ether extract, ash and crude fibers, but lower content of total carbohydrate, compared with other varieties. In addition, brown rice of all varieties had higher contents of crude protein, ether extract, ash and fiber but lower content of total carbohydrates, whereas the rice variety of black rice had a relatively high levels of mineral contents comparing with the other rice varieties. Results of Organoleptic evaluation indicated that, biscuit samples prepared using rice flour of the studied varieties as substitutions insted of wheat flour up to 50% were very acceptable. Where most samples have sensory characteristics scores higher than those of control (wheat flour biscuit).

Construction of Near Isogenic Lines for Pericarp Color and Evaluation on Their Near isogenicity in Rice

The inheritance of purple pericarp was studied through genetic analysis using F2, BC1F1 and F3 from a cross between a purple pericarp rice variety Zixiangnuo and a white pericarp rice variety Chunjiangnuo 2. Seven pairs of near isogenic lines (NILs) for pericarp color of rice were further constructed. Genetic analysis indicated that the purple pericarp was controlled by two complementary genes (Pb and Pp). Agronomic trait analysis and polymorphism analysis using SSR markers on these seven pairs of NILs were used in the evaluation of near-isogenicity. No significant differences in agronomic traits were found except 1000-grain weight between the NILs. The polymorphic SSR markers for the parents were only detected in target segments of the five pairs of NILs different in Pb, which revealed the ideal near isogenicity of them. However, for the two pairs of NILs different in Pp, the polymorphic markers for the two parents were detected as well as in non-targeted segments of chromosomes 11 and 12, respectively.

Chemical and Molecular Characterization of Fragrance in Black Glutinous Rice from Lao PDR

Fifty three accessions of lowland Black Glutinous Rice (BGR) and three white rice varieties from Lao PDR were evaluated for variations in 2-acetyl-1-pyrroline (2-AP), a main aroma compound present in fragrant rice and a 257 bp genomic fragment associated with a gene encoding 2-AP. The objective of this study was to characterize the variation in aromatic characters of Lao BGR by using chemical and molecular techniques. Thirty six out of the 56 accessions had aromatic properties, containing 2-acetyl-1-pyrroline (2-AP). The concentrations of 2-AP in unpolished samples were about 50% higher than those of the polished samples. The concentrations of 2-AP in BGR accessions were lower than those of white aromatic rice varieties in which 2-AP was highest in Kai Noi Leuang (0.688 ppm). Seventeen accessions and two of white rice (Kai Noi Leuang and TDK5) had a common 355 bp allele corresponding to that found in Calrose, a non-fragrant variety. A 257 bp allele was found in the 36 varieties of BGR and a local aromatic white rice variety, Hom Nang Nouan, sharing a common allele as in the fragrant variety KDML 105. Surprisingly, Kai Noi Leuang, a popular Lao local aromatic rice variety with the highest 2-AP concentration did not possess a 257 bp fragment which has been identified previously as a fragrant allele. This is the first study of the chemical and molecular aromatic properties of lowland BGR varieties of the Lao PDR and the data obtained will be valuable in screening other germplasm and in planning a breeding program in the country geared towards fragrant rices with superior agronomic properties.

Fine mapping and candidate gene analysis of purple pericarp gene Pb in rice (Oryza sativa L.)

Purple rice is a type of rice with anthocyanins deposited in its grain pericarp. The rice Pb gene controlling purple pericarp character is known to be on chromosome 4, and the purple color is dominant over white color. In this study, we fine mapped the Pb gene using two F2 segregating populations, i.e. Pei’ai 64S (white) × Yunanheixiannuo (purple) and Pei’ai 64S × Chuanheinuo (purple). In the first-pass mapping, the Pb gene was located in the region downstream the SSR marker RM3820. In the fine mapping, the candidate region was saturated with InDel and CAPS markers developed specifically for this study. Eventually, the Pb gene was mapped within the 25-kb region delimited by the upstream marker RID3 and the downstream marker RID4. The delimited region contained two annotated genes, Ra and bhlh16 (TIGR Rice Genome, R.5). The former is a homologue of the Myc transcription factor Lc controlling anthocyanin biosynthesis in maize, and the latter is a homologue of the TT8 gene, which is also an Myc transcription factor gene controlling the pericarp pigmentation in Arabidopsis thaliana. Sequence analysis showed that the exon 7 of the Ra gene of Yunanheixiannuo and Chuanheinuo had a 2-bp (GT) deletion compared with those of the white rice varieties Pei’ai 64S, 9311 and Nipponbare. A CAPS marker, CAPSRa, was developed according to the GT deletion for analysis of the two F2 segregating populations and 106 rice lines. The results showed that all F2 plants with white pericarp, and all non-purple rice lines (63 white and 22 red) contained no GT deletion, but all 20 purple rice lines contained the GT deletion. These results suggested that the Ra gene may be the Pb gene and the purple pericarp characteristic of rice is caused by the GT deletion within exon 7 of the Ra gene.

Global Dissemination of a Single Mutation Conferring White Pericarp in Rice

Here we report that the change from the red seeds of wild rice to the white seeds of cultivated rice (Oryza sativa) resulted from the strong selective sweep of a single mutation, a frame-shift deletion within the Rc gene that is found in 97.9% of white rice varieties today. A second mutation, also within Rc, is present in less than 3% of white accessions surveyed. Haplotype analysis revealed that the predominant mutation originated in the japonica subspecies and crossed both geographic and sterility barriers to move into the indica subspecies. A little less than one Mb of japonica DNA hitchhiked with the rc allele into most indica varieties, suggesting that other linked domestication alleles may have been transferred from japonica to indica along with white pericarp color. Our finding provides evidence of active cultural exchange among ancient farmers over the course of rice domestication coupled with very strong, positive selection for a single white allele in both subspecies of O. sativa.

Antioxidative Compounds in the Extracts of Black Rice Brans

Recently we found that extracts from ancient rice brans, especially those from black rice bran, possess strong scavenging activities for reactive oxygen species (ROS). In this study, we examined the origin of the ROS-scavenging activities in the black rice bran extracts, and identified candidate scavengers such as cyanidin-3-glucoside (Cy3-glu) and cyanidin. Although ferulic acid is known to be an antioxidative component of bran in currently available common white rice varieties, it was not found in the black rice bran extracts. The ROS-scavenging activities of Cy3-glu and cyanidin, which were identified in this study, were examined using the ESR-spin trap method and in terms of protective activity against effects of ultraviolet (UVB) irradiation on an epidermal cell line (HaCaT cell). These anthocyanin compounds were found to possess both strong ROS-scavenging activities and to suppress cell-damaging effects of UVB, indicating that both Cy-3-glu and cyanidin are the active components involved in the antioxidative activity of black rice bran extracts.

Bran extracts from pigmented rice seeds inhibit tumor promotion in lymphoblastoid B cells by phorbol ester

Using flow cytometry, we quantitatively evaluated anti-tumor-promoting activity of rice bran extracts by measuring inhibition of Epstein-Barr virus early-antigen activation (EBV-EA) induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). This assay measures anti-tumor-promoting activity and cytotoxicity of target substances using the same batch of cells. Using this short-term procedure, we have determined the anti-tumor-promoting activity of 70% ethanol-water extracts of bran (outer layer) from seeds of five pigmented rice cultivars: Jumlalocal-1, DZ 78, Elwee, LK1-3-6-12-1-1, and LK1A-2-12-1-1. The results show that, compared to an extract from the non-pigmented white cooking rice variety Chuchung, the extracts from the pigmented varieties strongly inhibited phorbol ester-induced tumor promotion in marmoset lymphoblastoid cells B95-8 in vitro. These findings may facilitate development and use of new health-promoting rice varieties.

Global dissemination of a single mutation conferring white pericarp in rice

Here we report that the change from the red seeds of wild rice to the white seeds of cultivated rice (Oryza sativa) resulted from the strong selective sweep of a single mutation, a frame-shift deletion within the Rc gene that is found in 97.9% of white rice varieties today. A second mutation, also within Rc, is present in less than 3% of white accessions surveyed. Haplotype analysis revealed that the predominant mutation originated in the japonica subspecies and crossed both geographic and sterility barriers to move into the indica subspecies. A little less than one Mb of japonica DNA hitchhiked with the rc allele into most indica varieties, suggesting that other linked domestication alleles may have been transferred from japonica to indica along with white pericarp color. Our finding provides evidence of active cultural exchange among ancient farmers over the course of rice domestication coupled with very strong, positive selection for a single white allele in both subspecies of O. sativa.