Distribution of amylose, nitrogen, and minerals in rice kernels with various characters

High-yield rice with rich nutrition and low toxicity can be obtained under potato-rice cropping system

BACKGROUND

Rice is often rotated with dryland crops to produce sufficient foodstuff, as rice is the main food crop of humans. In order to verify whether under the intensive rice-based cropping system, high yield and good quality of rice can be achieved simultaneously to ensure food security. Five long-term paddy-upland rotations - wheat-rice (WR), rapeseed-rice (RR), garlic-rice (GR), broad beans-rice (BR) and potato-rice (PR) - were conducted from 2014 to investigate rice yield, along with the profiling of 24 elements in rice grain.

RESULTS

Mg, Zn, Cu, As, Mo and Sb concentrations were highest in the aleurone layer, and Ag and Cd concentrations showed little variation among different parts of the rice grain. Al, Ti, V, Si, Fe and Tl concentrations in the endosperm under GR were higher, while the Se concentration under PR was the highest. Furthermore, the yield of GR and PR were higher than the other three rotations with N supplementation, and the sustainable yield index of PR and WR were larger than 0.8.

CONCLUSION

When we consider the concentration of toxic (As, Cd and Pb) and nutrient elements (Ca, Fe, Zn, Se, Cu and Mg) in the endosperm and grain yields, PR can simultaneously achieve high yield, high nutrition and low toxicity with different nitrogen treatments. Here we provide novel insights regarding the selection of rice-based cropping systems, focused on producing nutritious and safe rice with high grain yield. © 2024 Society of Chemical Industry.

Low temperature desolventization: effect on physico-chemical, functional and structural properties of rice bran protein

De-oiled rice bran is a good source of high-quality protein; however, the current practice of desolventization at high temperature (110-120 °C) denatures the protein, making its extraction difficult and uneconomical. The present study aims to investigate the effect of low temperature desolventization of de-oiled rice bran (LTDRB) on extraction, yield, and purity of protein and its comparison with protein obtained from high temperature desolventized de-oiled rice bran (HTDRB). The optimal conditions for preparation of protein from LTDRB were: extraction pH 11.00, extraction duration 52 min, and extraction temperature 58 °C resulting in an extraction efficiency, yield, and purity of 54.0, 7.23, and 78.70%, respectively. The LTDRB showed a positive impact on the color, solubility, foaming capacity and stability of protein whereas the absorption and emulsification properties were better for HTDRB protein. Significant decrease in enthalpy (ΔH) for denaturation was observed for LTDRB protein as compared to HTDRB protein. Scanning electron microscopy analysis revealed that HTDRB protein was more compact than LTDRB protein. LTDRB protein had smaller particle size distribution than HTDRB. Study suggested that low temperature desolventization can result in higher protein extraction with better physico-chemical, structural, and functional properties of protein obtained from DRB.

Differences in rice component distribution across layers and their relationship with taste

BACKGROUND

Rice taste is closely associated with endosperm composition, which varies among different rice layers. Although clarifying the relationship between this difference and nutritional taste can guide rice breeding and cultivation practices, research on this topic is limited.

RESULTS

Here, typical rice varieties having excellent and poor taste characteristics were selected to analyze the distribution characteristics and differences of their components. The varieties with excellent taste exhibited lower apparent amylose content (AAC) and protein content (PC), lesser short-chain (Fa) and long-chain (Fb3 ) amylopectin (AP) and more medium-chain (Fb1+2 ) AP, higher long-to-short chain ratio (Fa:Fb3 ), and higher nitrogen (N), magnesium (Mg) and calcium (Ca) content in layer 1 (L1) than the varieties with poor taste. Layer 2 (L2) played a key role in AAC and PC regulation in the varieties with excellent taste by reducing AAC and appropriately increasing PC, consequently improving rice taste. AP structure in layer 3 (L3) substantially affected the taste of the two types of varieties. The mineral content was the highest in L1, and increased potassium (K), Ca, and Mg content improved taste in all varieties.

CONCLUSION

AAC in each layer contributes to rice taste. PC and minerals primarily act on L1 and L2, whereas AP acts on L2 and L3. Therefore, the endosperm formation process should be exploited for improving rice taste. Furthermore, key resources and cultivation should be identified and regulated, respectively, to improve rice taste. © 2023 Society of Chemical Industry.

Variations in the Major Nutrient Composition of Dominant High-Yield Varieties (HYVs) in Parboiled and Polished Rice of Bangladesh

Rice (Oryza sativa L.) is the principal staple food, a fundamental component of food security, a significant source of energy and major nutrients, and a key player in the overall nutritional status in Bangladesh. Parboiling is a common rice-processing treatment in Bangladesh. Recently, polishing has also become a common practice among millers seeking to attract consumers. Polishing may influence the nutrient composition of rice. The present study aimed to investigate the impact of parboiling and polishing on the nutritional content of the five High Yield Varieties (HYVs) of rice (BR11, BRRI dhan28, BRRI dhan29, BRRI dhan49, and BRRI dhan84) and their percent contributions to the Recommended Dietary Allowances (RDA) of vitamins and minerals. All of the rice samples were analyzed for proximate parameters, vitamins (B1, B2, B3, B6, and folate), and minerals (Ca, Mg, Fe, Zn, Na, K, P). Moisture, ash, fat, and total dietary fiber (TDF) were determined gravimetrically, according to the AOAC Official Methods; protein was measured by the Kjeldahl method; B-group vitamins were measured using Ultra Pressure Liquid Chromatography; and mineral content was determined by ICP-OES. The energy, protein, fat, and total dietary fiber (TDF) content of the samples ranged between 342-357 kcal/100 g, 6.79-10.74 g/100 g, 0.31-1.69 g/100 g, and 2.59-3.92 g/100 g respectively. Thiamin, riboflavin, niacin, pyridoxin, and folate content ranged from 0.11-0.25 mg/100 g, 0.01-0.05 mg/100 g, 2.82-6.42 mg/100 g, 0.12-0.30 g/100 g, and 5.40-23.95 g/100 g respectively. In a comparison of parboiling and polishing, macronutrients and vitamin retention were higher in parboiled unpolished rice than in polished unparboiled rice. The minerals (mg/100 g) Ca, Mg, Fe, Zn, Na, K, and P were in the ranges 32.82-44.72, 30.69-58.34, 0.51-0.70,1.83-2.79, 5.00-5.36, 106.49-112.73, and 162.23-298.03. Minerals of BRRI dhan84 were unaffected by polishing and parboiling. BRRI dhan84 contributed a higher percentage of RDA of all B vitamins and minerals. Therefore, to reduce nutrient loss in rice, industries and consumers should be encouraged to avoid polishing or limit polishing to 10% DOM and to consume unpolished rice, either parboiled or unparboiled.

Foliar application of nanoceria attenuated cadmium stress in okra (Abelmoschus esculentus L.)

Foliar application of nanoparticles (NPs) as a means for ameliorating abiotic stress is increasingly employed in crop production. In this study, the potential of CeO₂-NPs as stress suppressants for cadmium (Cd)-stressed okra (Abelmoschus esculentus) plants was investigated, using two cycles of foliar application of CeO₂-NPs at 200, 400, and 600 mg/l. Compared to untreated stressed plants, Cd-stressed plants treated with CeO₂-NPs presented higher pigments (chlorophyll a and carotenoids). In contrast, foliar applications did not alter Cd root uptake and leaf bioaccumulation. Foliar CeO₂-NPs application modulated stress enzymes (APX, SOD, and GPx) in both roots and leaves of Cd-stressed plants, and led to decreases in Cd toxicity in plant's tissues. In addition, foliar application of CeO₂-NPs in Cd-stressed okra plants decreased fruit Cd contents, and improved fruit mineral elements and bioactive compounds. The infrared spectroscopic analysis of fruit tissues showed that foliar-applied CeO₂-NPs treatments did not induce chemical changes but induced conformational changes in fruit macromolecules. Additionally, CeO₂-NPs applications did not alter the eating quality indicator (Mg/K ratio) of okra fruits. Conclusively, the present study demonstrated that foliar application of CeO₂-NPs has the potential to ameliorate Cd toxicity in tissues and improve fruits of okra plants.

Functional foods and their impact on health

Functional foods play an important role in maintaining a healthy lifestyle and reducing the risk factors of various diseases. Most foods have a functional element which is responsible for improving the healthy state. All food substances such as fruits, vegetables, cereals, meat, fish, dairy contain functional ingredients. A wide range of naturally occurring substances from plant and animal sources having active components which play a role in physiological actions deserve attention for their optimal use in maintaining health. The market for functional food is keep on expanding, and the global market is projected to reach a value of at least 91 billion USD soon. Overwhelming evidence from preclinical (in vitro and in vivo) and clinical studies have shown that intake of functional foods could have an impact on the prevention of chronic diseases, especially cancer, cardiovascular diseases, gastrointestinal tract disorders and neurological diseases. Extensive research needs to be done to determine the potential health benefits for the proper application of these foods to improve health state and combat chronic disease progression. The aim of this review is to conduct a thorough literature survey, to understand the various classification of functional foods and their health benefits.

Genetic Approaches for Iron and Zinc Biofortification and Arsenic Decrease in Oryza sativa L. Grains

Rice is the staple diet to half of the world's population, being a major source of carbohydrates, vitamins, and some essential elements. However, rice naturally contains low amounts of essential minerals such as iron (Fe) and zinc (Zn), which are drastically decreased after milling. Thus, populations that consume mostly rice may have micronutrient deficiency, which is associated with different diseases. On the other hand, rice irrigated by flooding has a high ability to accumulate arsenic (As) in the grain. Therefore, when rice is grown in areas with contaminated soil or irrigation water, it represents a risk factor for consumers, since As is associated with cancer and other diseases. Different strategies have been used to mitigate micronutrient deficiencies such as Fe and Zn and to prevent As from entering the food chain. Each strategy has its positive and its negative sides. The development of genetically biofortified rice plants with Fe and Zn and with low As accumulation is one of the most promising strategies, since it does not represent an additional cost for farmers, and gives benefits to consumers as well. Considering the importance of genetic improvement (traditional or molecular) to decrease the impact of micronutrient deficiencies such as Fe and Zn and contamination with As, this review aimed to summarize the major efforts, advances, and challenges for genetic biofortification of Fe and Zn and decrease in As content in rice grains.

Laser microdissection transcriptome data derived gene regulatory networks of developing rice endosperm revealed tissue- and stage-specific regulators modulating starch metabolism

Laser microdissection applied on the developing rice endosperm revealed tissue- and stage-specific regulators modulating programmed cell death and desiccation tolerance mechanisms in the central starchy endosperm following starch metabolism. Rice (Oryza sativa L.) filial seed tissues are heterozygous in its function, which accumulate distinct storage compounds spatially in starchy endosperm and aleurone. In this study, we identified the 18 tissue- and stage-specific gene co-regulons in the developing endosperm by isolating four fine tissues dorsal aleurone layer (AL), central starchy endosperm (CSE), dorsal starchy endosperm (DSE), and lateral starchy endosperm (LSE) at two developmental stages (7 days after flowering, DAF and 12DAF) using laser microdissection (LM) coupled with gene expression analysis of a 44 K microarray. The derived co-expression regulatory networks depict that distinct set of starch biosynthesis genes expressed preferentially at first in CSE at 7 DAF and extend its spatial expression to LSE and DSE by 12 DAF. Interestingly, along with the peak of starch metabolism we noticed accumulation of transcripts related to phospholipid and glycolipid metabolism in CSE during 12 DAF. The spatial distribution of starch accumulation in distinct zones of starchy endosperm contains specific transcriptional factors and hormonal-regulated genes. Genes related to programmed cell death (PCD) were specifically expressed in CSE at 12DAF, when starch accumulation was already completed in that tissue. The aleurone layer present in the outermost endosperm accumulates transcripts of lipid, tricarboxylic acid metabolism, several transporters, while starch metabolism and PCD is not pronounced. These regulatory cascades are likely to play a critical role in determining the positional fate of cells and offer novel insights into the molecular physiological mechanisms of endosperm development from early to middle storage phase.

Modeling and Optimization of Process Parameters for Nutritional Enhancement in Enzymatic Milled Rice by Multiple Linear Regression (MLR) and Artificial Neural Network (ANN)

This study involves information about the concentrations of nutrients (proteins, phenolic compounds, free amino acids, minerals (Ca, P, and Iron), hardness) in milled rice processed with enzymes; xylanase and cellulase produced by Aspergillus awamori, MTCC 9166 and Trichoderma reese, MTCC164. Brown rice was processed with 60-100% enzyme (40 mL buffer -undiluted) for 30 to 150 min at 30 °C to 50 °C followed by polishing for 20-100 s at a safe moisture level. Multiple linear regression (MLR) and artificial neural network (ANN) models were used for process optimization of enzymes. The MLR correlation coefficient (R2) varied between 0.87-0.90, and the sum of square (SSE) was placed within 0.008-8.25. While the ANN R2 (correlation coefficient) varied between 0.97 and 0.9999(1), MSE changed from 0.005 to 6.13 representing that the ANN method has better execution across MLR. The optimized cellulase process parameters (87.2% concentration, 80.1 min process time, 33.95 °C temperature and 21.8 s milling time) and xylanase process parameters (85.7% enzyme crude, 77.1 min process time, 35 °C temperature and 20 s) facilitated the increase of Ca (70%), P (64%), Iron (17%), free amino acids (34%), phenolic compounds (78%) and protein (84%) and decreased hardness (20%) in milled rice. Scanning electron micrographs showed an increased rupture attributing to enzymes action on milled rice.

Fast spark discharge-laser-induced breakdown spectroscopy method for rice botanic origin determination

A simple, fast, and efficient spark discharge-laser-induced breakdown spectroscopy (SD-LIBS) method was developed for determining rice botanic origin using predictive modeling based on support vector machine (SVM). Seventy-two samples from four rice varieties (Guri, Irga 424, Puitá, and Taim) were analyzed by SD-LIBS. Spectral lines of C, Ca, Fe, Mg, N and Na were selected as input variables for prediction model fitting. The SVM algorithm parameters were optimized using a central composite design (CCD) to find the better classification performance. The optimum model for discriminating rice samples according to their botanical variety was obtained using C = 5.25 and γ = 0.119. This model achieved 96.4% of correct predictions in test samples and showed sensitivities and specificities per class within the range of 92-100%. The developed method is robust and eco-friendly for rice botanic identification since its prediction results are consistent and reproducible and its application does not generate chemical waste.

Quantification and Tissue Localization of Selenium in Rice (Oryza sativa L., Poaceae) Grains: A Perspective of Agronomic Biofortification

In worldwide production, rice is the second-most-grown crop. It is considered a staple food for many populations and, if naturally enriched in Se, has a huge potential to reduce nutrient deficiencies in foodstuff for human consumption. This study aimed to develop an agronomic itinerary for Se biofortification of Oryza sativa L. (Poaceae) and assess potential physicochemical deviations. Trials were implemented in rice paddy field with known soil and water characteristics and two genotypes resulting from genetic breeding (OP1505 and OP1509) were selected for evaluation. Plants were sprayed at booting, anthesis and milky grain phases with two different foliar fertilizers (sodium selenate and sodium selenite) at different concentrations (25, 50, 75 and 100 g Se·ha⁻¹). After grain harvesting, the application of selenate showed 4.9–7.1 fold increases, whereas selenite increased 5.9–8.4-fold in OP1509 and OP1505, respectively. In brown grain, it was found that in the highest treatment selenate or selenite triggered much higher Se accumulation in OP1505 relatively to OP1509, and that no relevant variation was found with selenate or selenite spraying in each genotype. Total protein increased exponentially in OP1505 genotype when selenite was applied, and higher dosage of Se also increased grain weight and total protein content. It was concluded that, through agronomic biofortification, rice grain can be enriched with Se without impairing its quality, thus highlighting its value in general for the industry and consumers with special needs.

Rice starch accumulation at different endosperm regions and physical properties under nitrogen treatment at panicle initiation stage

The quality of rice grain is characterized by the component, structure and physicochemical properties of starch accumulated in endosperm cell. Nitrogen uptake strongly affects rice growth and starch development. In this study, Nangeng 9108 was used to investigated the accumulation of starch in different positions of the endosperm and physical properties of starch under nitrogen treatment of panicle initiation (PI) stage. Compared with the control group (CG), nitrogen treatment group (NTG) featured a higher number of grains per panicle and 1000-grain weight. Nitrogen treatment significantly increased starch accumulation among different regions during endosperm development, which was expressed as central endosperm cells > sub-aleurone cells of abdominal endosperm > sub-aleurone cells of dorsal endosperm. The amyloplast increased by constricting and budding-type division, generated a bead-like structure and derived some vesicles. The particle size of the starch granules obtained from the NTG was smaller and the apparent amylose content was lower than those of the CG, resulting in higher relative crystallinity. Nitrogen treatment promoted double helical components and provided a higher degree of order at short-rang scale for the starch granules. This study indicated that nitrogen significantly affected the accumulation and physicochemical properties of starch in the endosperm.

Assessing mineral profiles for rice flour fraud detection by principal component analysis based data fusion

The present work proposes to detect adulteration in rice flour using mineral profiles. Eighty-seven flour samples from two rice kinds (Indica and Japonica) plus thirty adulterated flour samples were analyzed by ICP OES. After obtaining the quantitative elemental fingerprint of the samples, PCA and LDA were applied. Binary and multiclass associations were considered to assess rice flour authenticity through fraud identification. Models based on element predictors showed accuracies ranging from 72 to 88% to distinguish adulterated and unadulterated samples. The fusion of the mineral features with the principal components (PCs) obtained from PCA provided classification rates of 100% in training samples, and 91-100% in test samples. The proposed method proved to be a useful tool for quality control in the rice industry since a perfect success rate was achieved for rice flour fraud detection.

Development of lightly milled black rice with easy cooking and retaining health benefits

Consumers are reluctant to eat pigmented rice due to cooking difficulties and harder texture than white rice. In this study, paddy samples of black rice (Hom Nil cultivar) were milled for 0, 10, 30, 60 and 100 s and degree of milling (DOM) ~ 0, 6, 12, 22 and 30% were obtained. Head rice yield, physicochemical properties, cooking qualities, nutrients, resistant starch content, antioxidant properties, and sensorial qualities were studied. Milling at 10 s (DOM ~ 6%) did not remove all bran fractions. Head rice yield retained at 70.33%. Lightness (L*) and redness (a*) of black rice remained constant until DOM ~ 20% but yellowness (b*) gradually increased. Nutrients were embedded at different locations in grain kernels. All nutrients decreased with DOM but in different extents. Milling at 10 s generated loss of anthocyanin (70%), fat (44%), ash (33%) and phenolic compounds (31%). Comparably tiny losses were observed in protein (15%) and dietary fiber (25%). However, cooking qualities of black rice were substantially improved. Cooking time reduced from 22 to 15 min with increases in water uptake ratio and volume expansion ratio. Additionally cooked black rice had impressively softer texture. Panelist appreciated the change in odor, flavor, texture attributes and palatability of the rice.

Nutritional variability and milling losses of rice landraces from Arunachal Pradesh, Northeast India

Rice landraces of North-East India have wide bio-diversity but remained nutritionally uncharacterized. Nutritional profiling of 33 indigenous rice landraces from the state of Arunachal Pradesh, Northeast India, and effect milling was evaluated. Total dietary fiber (5.22 g/100 g) was significantly higher than high yielding or hybrid cultivars. Principal nutrient variability of brown rice were: ash (13% c. v.) > insoluble dietary fibre, IDF (12% c. v.) > protein (11.% c.v.) fat (11% c. v.). Compositional diversity exists among rice landraces. Average iron was lesser but zinc content was higher than popular high yielding cultivars. Nutrient changes due to milling were most profound for thiamin (-69%), IDF (-66%) followed by phytate (-66%). Nutritionally Arunachal rice landraces are comparable to high yielding cultivars with added advantage of significantly higher total dietary fiber and lower phytate content. Thus, Arunachal rice landraces represents an agronomically and nutritionally important pool for rice improvement/breeding.

Improvement of germinated brown rice quality with autoclaving treatment

Germinated brown rice (GBR) is a popular functional food containing considerable amounts of beneficial nutrients and bioactive compounds. Here, autoclaving at 115°C for 20 min was employed to process GBR (AGBR) to evaluate the effect of autoclaving on the nutritional and health function of GBR in microstructure, taste value, aroma, as well as the physiological ingredients. The results showed that autoclaving treatment influenced the starch gelatinization and aroma to improve the taste of cooked AGBR. Autoclaving treatment significantly increased the gamma‐aminobutyric acid (GABA) and ferulic acid levels of AGBR (p < .05). In addition, consuming AGBR for 1 month significantly decreased the fasting plasma glucose (FPG), 0.5, 1, and 2 hr postprandial plasma glucose (PPG), triglyceride (TG), total cholesterol (TC), high‐density lipoprotein cholesterol (HDL‐c), and low‐density lipoprotein cholesterol (LDL‐c) in metabolic syndrome (MS) patients (p < .05). Therefore, autoclaving treatment, as a promising processing strategy, may both improve the sensory attributes and the nutrition of GBR.

Biochemical composition distribution in different grain layers is associated with the edible quality of rice cultivars

Clarifying the association of differences in endosperm biochemical composition with nutrient and edible quality can guide rice breeding and cultivation. In this study, very-low-amylose-content (LAC), Japanese good-taste (JTC), Northeast China good-taste (CTC), and Northeast China high-yield (CHC) cultivars were milled to obtain four layers (L1-L4) from outside-in, and then analyzed for apparent amylose content (AAC), protein content (PC), amino acids, soluble sugars, and minerals. The association of these compositions and Rapid-Visco analysis values with taste was also examined. LAC had low AAC, high amino acid and mineral content, and the highest taste value. Taste was significantly affected by AAC and soluble sugar in L3, and by PC in the L2 layer. High levels of amino acid in L2 and L3 improved the taste, as did Mg, P, and Ca in L1. On the whole, starch factors had the highest contribution to taste, followed by minerals, amino acids, and PC.

Effect of degree of milling on physicochemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars

The effects of degree of milling (DOM) between 0 and 8% on physico-chemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars were studied. Ash, protein, lipids and minerals decreased while blue value and crystallinity increased with increase in DOM. The colour parameters (a∗, b∗) and cooking time (CT) decreased while L∗(lightness) increased with increase in DOM. Elongation ratio (ER), gruel solid loss (GSL), length/breadth (L/B) and paste viscosities during cooking increased with increase in DOM. Short grain rice contained lower ash, protein, lipids, Mn, K, Ca, CT and GSL than long grain while the later showed higher crystallinity, Mn, P, K, Ca and ER. Paste and dough characteristics measured using Rheometer and Mixolab, respectively correlated well and differed with cultivar and DOM. Short and long grain cultivars showed variation in loss of different chemical constituents during varied DOM causing variation in cooking characteristics.

Phenolic acids, anthocyanins, proanthocyanidins, antioxidant activity, minerals and their correlations in non-pigmented, red, and black rice

Soluble-free, soluble-conjugated, insoluble-bound phenolics and antioxidant activity, flavonoid (TFC), proanthocyanidins (TPAC), anthocyanins and minerals of fifteen whole rice grains with different colors were investigated. Soluble-free protocatechuic and vanillic acids were only quantified in black rice, which had the most quantities. Non-pigmented rice had no detectable conjugated protocatechuic and 2,5-dihydroxybenzoic acids both of which were found in black and red rice, respectively. The main bound phenolic acids were ferulic and p-coumaric, as well as 2,5-dihydroxybenzoic in red rice and protocatechuic and vanillic acids in black rice. Soluble-conjugated phenolics, TFC, and anthocyanins were negatively correlated with L^∗, b^∗, C and H° values. TPAC was positively correlated with a^∗ (P<0.01). Protocatechuic, vanillic, syringic and ferulic acids were associated with TPC and antioxidant activity in the soluble-conjugated fraction while protocatechuic and ferulic acid were correlated with those in the insoluble-bound fraction. Principal component analysis divided samples into non-pigmented, red and black rice groups.

Determination of Optimal Harvest Time of Chuchung Variety Green Rice(®) (Oryza sativa L.) with High Contents of GABA, γ-Oryzanol, and α-Tocopherol

In our previous study, an early-maturing variety of rice (Oryza sativa L.), Jinbu can have feature with unique green color, various phytochemicals as well as nutritive components by the optimal early harvesting, called Green Rice(®) (GR). The aims of the present field experiments were to evaluate the changes in the weight of 1,000 kernels, yield, and contents of proximate and bioactive compounds in Chuchung, a mid-late maturing variety, during the pre-harvest maturation of rough rice and to research the appropriate harvest time and potent bioactivity of Chuchung GR. The weights of 1,000 kernels of Chuchung GR dramatically increased until 27 days after heading (DAH). The yields of Chuchung GR declined after 27 DAH and significantly declined to 0.0% after 45 DAH. The caloric value and total mineral contents were higher in the GR than in the full ripe stage, the brown rice (BR). In the GR, the contents of bioactive compounds, such as γ-aminobutyric acid, γ-oryzanol, and α-tocopherol, were much higher (P<0.05) than those in the BR, specifically during 24~27 DAH. Therefore, bioactive Chuchung GR can be produced with a reasonable yield at 24~27 DAH and it could be useful for applications in various nutritive and functional food products.

Laser microdissection-based gene expression analysis in the aleurone layer and starchy endosperm of developing rice caryopses in the early storage phase

BACKGROUND

Rice endosperm is composed of aleurone cells in the outermost layers and starchy endosperm cells in the inner part. The aleurone layer accumulates lipids, whereas starchy endosperm mainly accumulates starch. During the ripening stage, the starch accumulation rate is known to be asynchronous, depending on the position of the starchy endosperm. Different physiological and molecular mechanisms are hypothesized to underlie the qualitative and quantitative differences in storage products among developing rice endosperm tissues.

RESULTS

Target cells in aleurone layers and starchy endosperm were isolated by laser microdissection (LM), and RNAs were extracted from each endosperm tissue in the early storage phase. Genes important for carbohydrate metabolism in developing endosperm were analyzed using qRT-PCR, and some of the genes showed specific localization in either tissue of the endosperm. Aleurone layer-specific gene expression of a sucrose transporter, OsSUT1, suggested that the gene functions in sucrose uptake into aleurone cells. The expression levels of ADP-glucose pyrophosphorylase (AGPL2 and AGPS2b) in each endosperm tissue spatially corresponded to the distribution of starch granules differentially observed among endosperm tissues. By contrast, expressions of genes for sucrose cleavage-hexokinase, UDP-glucose pyrophosphorylase, and phosphoglucomutase-were observed in all endosperm tissues tested. Aleurone cells predominantly expressed mRNAs for the TCA cycle and oxidative phosphorylation. This finding was supported by the presence of oxygen (8 % concentration) and large numbers of mitochondria in the aleurone layers. In contrast, oxygen was absent and only a few mitochondria were observed in the starchy endosperm. Genes for carbon fixation and the GS/GOGAT cycle were expressed highly in aleurone cells compared to starchy endosperm.

CONCLUSIONS

The transcript level of AGPL2 and AGPS2b encoding ADP-glucose pyrophosphorylase appears to regulate the asynchronous development of starch granules in developing caryopses. Aleurone cells appear to generate, at least partially, ATP via aerobic respiration as observed from specific expression of identified genes and large numbers of mitochondria. The LM-based expression analysis and physiological experiments provide insight into the molecular basis of the spatial and nutritional differences between rice aleurone cells and starchy endosperm cells.

Mapping of Quantitative Trait Loci for Contents of Macro- and Microelements in Milled Rice (Oryza sativa L.)

Macro- and microelement contents are important traits for nutritional quality in rice. In this study, quantitative trait loci (QTLs) for the contents of seven mineral elements in milled rice were detected using recombinant inbred lines (RILs) of the indica rice cross Zhenshan 97/Milyang 46, followed by the validation and fine mapping of a QTL region on the short arm of chromosome 6. A total of 20 QTLs distributed on chromosomes 1, 3, 5, 6, 10, and 11 were detected in the RIL population. Co-localizations of QTLs for multiple traits were observed, of which the qP3/qMg3/qZn3 region was shown to have the largest effects for the contents of phosphorus, magnesium, and zinc, and the qK6.1/qCa6/qZn6/qMn6/qCu6 region was found to be responsible for five of the seven traits. Using near isogenic lines having sequential segregating region, the target QTL on chromosome 6 was delimitated to a 29.9 kb region flanked by RM19410 and Si2944. This QTL showed major effects for all seven traits, with the enhancing alleles derived from the male parent Milyang 46.

Cytotoxic and apoptotic-inducing effects of purple rice extracts and chemotherapeutic drugs on human cancer cell lines

Pigmented rice is mainly black, red, and dark purple, and contains a variety of flavones, tannin, polyphenols, sterols, tocopherols, γ-oryzanols, amino acids, and essential oils. The present study evaluated the cytotoxic effects of purple rice extracts (PREs) combined with chemotherapeutic drugs on human cancer cells and mechanisms of cell death. Methanolic (MeOH) and dichloromethane (DCM) extracts of three cultivars of purple rice in Thailand: Doisaket (DSK), Nan and Payao (PYO), were tested and compared with white rice (KK6). Cytotoxicity was determined by 3-(4, 5-dimethyl)-2, 5-diphenyltetrazolium bromide (MTT) assay in human hepatocellular carcinoma HepG2, prostate cancer LNCaP and murine normal fibroblast NIH3T3 cells. MeOH-PYO-PRE was the most cytotoxic and inhibited HepG2 cell growth more than that of LNCaP cells but was not toxic to NIH3T3 cells. When PREs were combined with paclitaxel or vinblastine, they showed additive cytotoxic effects on HepG2 and LNCaP cells, except for MeOH-PYO-PRE which showed synergistic effects on HepG2 cells when combined with vinblastine. MeOH-PYO-PRE plus vinblastine induced HepG2 cell apoptosis with loss of mitochondrial transmembrane potential (MTP) but no ROS production. MeOH-PYO-PRE-treated HepG2 cells underwent apoptosis via caspase-9 and-3 activation. The level of γ-oryzanol was highest in DCM-PYO-PRE (44.17 mg/g) whereas anthocyanin content was high in MeOH-PYO-PRE (5.80 mg/g). In conclusion, methanolic Payao purple rice extract was mostly toxic to human HepG2 cells and synergistically enhanced the cytotoxicity of vinblastine. Human HepG2 cell apoptosis induced by MeOH-PYO-PRE and vinblastine was mediated through a mitochondrial pathway.

Phenolic profiles and antioxidant activity in four tissue fractions of whole brown rice

In view of the fact that different types of processed rice contain different tissue fractions, the present study quantified phenolic profiles and antioxidant activity in the pericarp, aleurone layer, embryo and endosperm fractions of brown rice.

Enzymatic polishing of cereal grains for improved nutrient retainment

Consumer acceptance of food products is largely driven by the dietary and functional quality of their ingredients. Though whole cereal grains are well known for bioactive components, scientists are facing dire need for better technologies to prevent the nutritional losses incurred through the conventional food processing technologies. Application of enzyme for depolymerisation of carbohydrates present in bran layer of grain is becoming an efficient method for phenolic mobilization and dietary fiber solubilisation. The present article emphasizes deep insights about the application of enzyme as an alternative technology for cereal grain processing to improve the product quality while forbidding the nutritional losses in an eco-friendly manner.

Effect of cerium oxide nanoparticles on the quality of rice ( Oryza sativa L.) grains

Despite the remarkable number of publications on the interaction of engineered nanoparticles (ENPs) with plants, knowledge of the implications of ENPs in the nutritional value of food crops is still limited. This research was performed to study the quality of rice grains harvested from plants grown in soil treated with cerium oxide nanoparticles (nCeO2). Three rice varieties (high, medium, and low amylose) were cultivated to full maturity in soil amended with nCeO2 at 0 and 500 mg kg(-1) soil. Ce accumulation, nutrient content, antioxidant property, and nutritional quality of the rice grains were evaluated. Results showed that rice grains from nCeO2-treated plants had less Fe, S, prolamin, glutelin, lauric and valeric acids, and starch. Moreover, the nCeO2 reduced in grains all antioxidant values, except flavonoids. Medium- and low-amylose varieties accumulated more Ce in grains than the high-amylose variety, but the grain quality of the medium-amylose variety showed higher sensitivity to the nCeO2 treatment. These results indicate that nCeO2 could compromise the quality of rice. To the authors' knowledge, this is the first report on the effects nCeO2 on rice grain quality.