A review on nutritional properties, shelf life, health aspects, and consumption of brown rice in comparison with white rice

How much does the carcinogenic risk of inorganic arsenic exposure from rice increase with higher brown rice consumption? An estimation for five regions around the world

Substituting brown rice for white rice can increase the carcinogenic risk of inorganic arsenic (iAs) exposure, given that brown rice has a higher iAs content than white rice. This study estimated changes in the incremental lifetime cancer risk (ILCR) of iAs exposure from rice with increases in the proportion of brown to total rice consumption (PBT) in five regions around the world, including North America, Latin America, Europe, Asia, and Oceania. The results demonstrated that the magnitude of the increase in the ILCR of iAs exposure from rice expressed as an increase in PBT, ranged from 0.02 to 0.43 per 10,000 people for each 10 % increase in PBT. The highest increase was observed in Asia, followed by Latin America, North America, Oceania, and Europe. The daily rice consumption rate rather than the increase in iAs content is the critical factor responsible for regional differences in higher carcinogenic risk with increased PBT. This study also suggests that when considering the carcinogenic risks of iAs exposure from rice, substituting brown rice for white rice is feasible in North America and Europe but not in Asia and Latin America, while in Oceania, a partial substitution of brown rice for white rice (<55 %) is feasible.

Predictive modeling of rice milling degree for three typical Chinese rice varieties using interpretative machine learning methods

Brown rice over-milling causes high economic and nutrient loss. The rice degree of milling (DOM) detection and prediction remain a challenge for moderate processing. In this study, a self-established grain image acquisition platform was built. Degree of bran layer remaining (DOR) datasets is established with image capturing and processing (grain color, texture, and shape features extraction). The mapping relationship between DOR and the DOM is in-depth analyzed. Rice grain DOR typical machine learning and deep learning prediction models are established. The results indicate that the optimized Catboost model can be established with cross-validation and grid search method, with the best accuracy improving from 84.28% to 91.24%, achieving precision 91.31%, recall 90.89%, and F1-score 91.07%. Shapley additive explanations analysis indicates that color, texture, and shape feature affect Catboost prediction accuracy, the feature importance: color > texture > shape. The YCbCr-Cb_ske and GLCM-Contrast features make the most significant contribution to rice milling quality prediction. The feature importance provides theoretical and practical guidance for grain DOM prediction model. PRACTICAL APPLICATION: Rice milling degree prediction and detection are valuable for rice milling process in practical application. In this paper, image processing and machine learning methods provide an automated, nondestructive, and cost-effective way to predict the quality of rice. The study may serve as a valuable reference for improving rice milling methods, retaining rice nutrition, and reducing broken rice yield.

Evaluation of the trade-off between variety, processing, and low-GI claim in ready-to-eat rice

An increasing number of consumers demand healthier, more convenient, and sustainable food products, including rice, a staple worldwide. Food manufacturers have responded to this trend by considering food's intrinsic and extrinsic aspects. This study evaluated the importance of variety, processing, and claims on willingness to try ready-to-eat rice (RTE-rice). It also analyses the influence of consumer attitudes on the importance of attributes and willingness to try. The results showed that processing significantly influenced willingness to try RTE-rice, revealing consumers' greater preference for whole grain than milled rice with added bran. Claims had the least relevant importance. However, low glycaemic index had a positive impact, indicating its potential to influence consumer purchasing attitudes and promote healthier rice consumption. Additionally, three groups were created based on attitudinal factors. Naturalness-oriented and convenience-oriented groups were more likely to try RTE-rice. However, the reasons that motivate them may be different; this latter could be the ease of the service offered, while for the group focused on naturalness, they may have perceived through the ingredients and claimed that the product, despite being convenient, can bring benefits, thus perceiving them as natural.

Insight into the nutritional, physicochemical, functional, antioxidative properties and in vitro gastrointestinal digestibility of selected Thai rice: Comparative and multivariate studies

Nutritional, physicochemical, functional, antioxidative and digestion properties of brown and white rice flours from four Thai rice varieties (Luangpatue, upland rice, RD43, and Hommali) were investigated and compared. Due to differences in grain color, the color parameters of flours varied significantly. Protein, fat, ash, carbohydrate, and moisture content, total dietary fiber, and calories of these rice flours were 6.94-10.21%, 1.68-3.16%. 0.554-1.442%, 71.20-79.68%, 9.79-10.53%, 1.07-3.64%, and 350.82-362.73 kcal/100g, respectively. RD43 brown rice (18.4%) and Luangpatue white rice (26.5%) respectively exhibited the lowest and highest amylose content. Luangpatue rice flours also showed higher swelling power, setback value, final viscosity, and thermal properties than other varieties. The variations in hydration properties and oil absorption index were noticeable among these rice flours. In addition, the highest level of total phenolic content and antioxidant activity led to the lowest estimated glycemic index (eGI = 62.92) found in upland brown rice. It was confirmed by the multivariate analysis results. This study reported the diverse physicochemical properties and composition-property relationships of two kinds of flours from four rice varieties collected from Thailand for the first time. It exhibited possible capabilities for the development of various rice-based products that promote health based on their characteristics on industrial scale.

Exploring Rice Consumption Habits and Determinants of Choice, Aiming for the Development and Promotion of Rice Products with a Low Glycaemic Index

Current consumption drivers, particularly those related to health and wellbeing, have been influencing trends for the lower consumption of cereals, particularly rice, due to their typical high glycaemic index (GIs) and consequent impacts on obesity. To satisfy this consumer concern, more food innovations that promote healthy eating habits are required. Such innovations must be consumer-oriented to succeed, understanding the dynamics of consumer habits and responding to consumer expectations. This study explored these habits, from acquisition to consumption practices, and the expectations of the European market from the perspective of the major European consumer, Portugal, to obtain insights that support the development of low glycaemic index (GI) rice products. A mixed-methods approach was applied. For the first quantitative questionnaire, 256 Portuguese rice consumers aged 18-73 years were recruited. Twenty-four individuals were selected according to their gender and rice consumption profiles for in-depth interviews. The results confirmed that rice was the main side dish for the participants and was mainly consumed at home, cooked from raw milled rice. The drivers of consumption differ according to the provisioning process stage. In the acquisition stage, participants reported benefits from the rice's dynamic market by comparing products on price, brand, and rice types. In the preparation stage, participants reported the adequacy of the recipe and occasion, while in the consumption stage, participants enhanced their sensory preferences, depending on the rice dish. Although the GI concept was unknown to half of the participants, it was perceived as interesting and positive for healthy eating. Consumers showed concern about the taste and naturalness of the product, preferring it to be as close to a homemade dish as possible. The negative perceptions we verified were interpreted to be due to a lack of knowledge about the GI concept. Therefore, awareness actions and informative campaigns are recommended to promote low-GI rice products.

Untargeted Lipidomics Reveal Quality Changes in High-Moisture Japonica Brown Rice at Different Storage Temperatures

Low temperatures are an effective way of delaying grain rancidity and deterioration. However, little is known about the difference in quality changes in high-moisture japonica brown rice at different storage temperatures. In this study, the storage quality changes in japonica brown rice with a 15.50% moisture content stored at 15 °C, 20 °C, and 25 °C were investigated. In addition, an untargeted lipidomics analysis coupled with gas chromatography and mass spectrometry (GC-MS) was applied to analyze the volatile compounds and metabolite changes in the high-moisture japonica brown rice. The results showed that storage at 15 °C could well maintain the color and aroma stability of the brown rice and delay the increase in fatty acid value (FAV). The lipidomics results showed that storage at 15 °C delayed glycerolipid and sphingolipid metabolism and reduced glycerophospholipid catabolism in the brown rice. The low-temperature environment regulated these three metabolic pathways to maintain higher contents of triglycerides (TG), phosphatidylserine (PS), abd phosphatidylethanolamine (PE), and lower contents of diglycerides (DG), OAcyl-(gamma-hydroxy) FA (OAHFA), ceramides (Cer), and glycosylceramides (Hex1Cer) in the high-moisture japonica brown rice, which maintained the storage stability of the brown rice. Our results proposed the cryoprotection mechanism of postharvest brown rice from the perspective of volatile compounds and metabolite changes, providing a foothold for the further exploration of low-temperature storage as a safe and efficient cryoprotectant in the grain storage field.

Strategies to fortify the nutritional values of polished rice by implanting selective traits from brown rice: A nutrigenomics-based approach

Whole-grain cereals are important components of a healthy diet. It reduces the risk of many deadly diseases like cardiovascular diseases, diabetes, cancer, etc. Brown rice is an example of whole grain food, which is highly nutritious due to the presence of various bioactive compounds (flavonoids, phenolics, vitamins, phytosterols, oils, etc.) associated with the rice bran layer of brown rice. White rice is devoid of the nutritious rice bran layer and thus lacks the bioactive compounds which are the major attractants of brown rice. Therefore, to confer health benefits to the public at large, the nutrigenomic potential of white rice may be improved by integrating the phytochemicals associated with the rice bran layer of brown rice into it via biofortification processes like conventional breeding, agronomic practices, metabolic engineering, CRISPR/Cas9 technology, and RNAi techniques. Thus, this review article focuses on improving the nutritional qualities of white/polished rice through biofortification processes, utilizing new breeding technologies (NBTs).

Effect of processing methods and storage on the bioactive compounds of black rice (Oryza sativa L.): a review

Compared to brown and white rice, black rice contains more nutrients and numerous unique bioactive substances, such as essential amino acids, dietary fiber, γ-oryzanols, γ-aminobutyric acid, phenolic compounds, and anthocyanins, which makes it highly valuable for development and use. Whole-grain black rice typically requires a certain amount of processing prior to consumption, with the primary goal of enhancing the taste and texture of whole grains and their products. However, various new processing technologies have been effectively applied to the processing of black rice and the enhancement of its qualitative characteristics, but they also have both positive and negative effects on its nutritional quality. Therefore, evaluation of changes in concentrations of the bioactive substances as natural antioxidants due to processing and storage conditions is critical for establishing dietary guidelines for rice. This review highlights the primary bioactive components of black rice and provides a discussion of the impact of processing methods and storage on the bioactive components of black rice. Furthermore, we summarized the issues that currently exist in the processing and storage of black rice.

Stabilization of Rice Bran: A Review

One of the major problems in food science is meeting the demand of the world's growing population, despite environmental limitations such as climate change, water scarcity, land degradation, marine pollution, and desertification. Preventing food from going to waste and utilizing nutritive by-products as food rather than feed are easy and powerful strategies for overcoming this problem. Rice is an important staple food crop for more than half of the world's population and substantial quantities of rice bran emerge as the main by-product of rice grain milling. Usually, rice bran is used as animal feed or discarded as waste. Although it is highly nutritious and comprises many bioactive compounds with considerable health benefits, the rapid deterioration of bran limits the exploitation of the full potential of rice bran. Hydrolytic rancidity is the main obstacle to using rice bran as food, and the enzyme inactivation process, which is termed stabilization, is the only way to prevent it. This study reviews the methods of stabilizing rice bran and other rice-milling by-products comprising rice bran in the context of the efficiency of the process upon storage. The effect of the process on the components of rice bran is also discussed.

Effect of storage on the nutritional and antioxidant properties of brown Basmati rice

The purpose of the present study is to evaluate the effect of storage time and temperature on the nutritional and antioxidant values of different varieties of brown rice. PARB approved indigenous Basmati varieties (Basmati 86, Basmati 515, Basmati super, Basmati super fine and Basmati kainat) were procured and initially tested for physicochemical parameters, including moisture, ash, lipids, proteins, carbohydrates, and fibers from the brown rice powder. Similarly, antioxidant capacity of these brown rice samples was assessed in terms of total phenolic content and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging potential. Samples of brown rice were stored for 3 and 6 months at 25 and 5°C. On increasing the storage time and temperature, antioxidant activity of rice decreases up to 50%. Nutritional parameters, such as minerals, carbohydrates, and fatty acids were characterized using UV/Vis spectrophotometer, ICP-OES, GC-MS, and HPLC, revealing significant changes in the chemical composition of brown rice. Observation indicates that storage at high temperatures leads to a rapid decrease in carbohydrate and moisture content than at lower temperatures. The protein and ash content remains controlled and integrate with the mineral composition found. Decrease in the glucose and fructose amount was observed in brown rice varieties except for Basmati super fine and Basmati kainat at 5°C. Regarding fatty acids, oleic and linoleic acids were prominent in oils extracted from the different brown rice varieties, and their content was reduced during the storage due to conversion to behenic, and erucic acids, respectively. From the present study, it can be concluded that low storage temperatures reduce the loss of nutrients, offering better nutritional quality for the consumer.

Eating Quality and In Vitro Digestibility of Brown Rice Improved by Ascorbic Acid Treatments

The effects of ascorbic acid treatment alone and in combination with degreasing or hydrothermal treatment on eating quality and in vitro digestibility of brown rice were explored for improving poor mouthfeel and low digestibility, and the improvement mechanism was investigated. The results indicated that the texture of cooked brown rice was significantly improved by degreasing combined with ascorbic acid hydrothermal treatment; the hardness and chewiness decreased to the level of polished rice; the stickiness increased three times of the cooked untreated brown rice; and the sensory score and in vitro digestibility were significantly enhanced from 68.20 and 61.37% to 83.70 and 79.53%, respectively. In addition, the relative crystallinity and water contact angle of treated brown rice were respectively reduced from 32.74% and 113.39° to 22.55% and 64.93°, and normal temperature water uptake significantly increased. Scanning electron microscope showed that the separation of starch granules occurred inside cooked brown rice grain obviously. The improvement of eating quality and in vitro digestibility of brown rice is conducive to enhancing the consumers acceptance and human health.

Dietary Fibre Impacts the Texture of Cooked Whole Grain Rice

Consumers' general preference for white rice over whole grain rice stems from the hardness and low palatability of cooked whole grain rice; however, strong links have been found between consuming a large amount of white rice, leading a sedentary lifestyle, and acquiring type 2 diabetes. This led us to formulate a new breeding goal to improve the softness and palatability of whole grain rice while promoting its nutritional value. In this study, the association between dietary fibre profiles (using an enzymatic method combined with high-performance liquid chromatography) and textural properties of whole grain rice (using a texture analyser) was observed. The results showed that a variation in the ratio of soluble dietary fibre (SDF) and insoluble dietary fibre (IDF) influenced the textural characteristics of cooked whole grain rice; found a strong association between SDF to IDF ratio and hardness (r = -0.74, p < 0.01) or gumminess (r = -0.69, p < 0.01) of cooked whole grain rice, and demonstrated that the SDF to IDF ratio was also moderately correlated with cohesiveness (r = -0.45, p < 0.05), chewiness (r = -0.55, p < 0.01), and adhesiveness (r = 0.45, p < 0.05) of cooked whole grain rice. It is suggested that the SDF to IDF ratio can be used as a biomarker for breeding soft and highly palatable whole grain rice of cultivated tropical indica rice to achieve consumer well-being. Lastly, a simple modified method from the alkaline disintegration test was developed for high-throughput screening of dietary fibre profiles in the whole grain indica rice samples.

Deciphering the Genetic Architecture of Color Variation in Whole Grain Rice by Genome-Wide Association

Whole grain rice is recommended in a natural healthy diet because of its high nutritional and healthful benefits compared to polished or white rice. The whole grain contains the pericarp with many assorted colors (such as brown, red, and black) associated with taste and commercial quality. The color attributes of whole grain or brown rice are usually undesirable and need to be improved. To decipher the genetic basis of color variation in the whole grain rice, we conducted a genome-wide association analysis of three parameters of grain colors (brightness, redness, and yellowness) in a panel of 682 rice accessions. Twenty-six loci were identified for the color parameters, implying that grain color is under polygenic control. Among them, some major-effect loci were co-localized with the previously identified genes such as Rc and Rd. To eliminate the possible mask of Rc on other loci influencing grain color, we performed the association analysis in a subset of the panel that excluded the pigmented (red and black) rice. Eighteen loci or SNPs were detected to be associated with grain color in the subpopulation, many of which were not reported before. Two significant peak SNP regions on chromosomes 1 and 9 were validated using near-isogenic lines. Based on differential expression analysis of annotated genes within the SNP regions and metabolic analysis of pooled extreme samples, we found at least three annotated genes as potential candidates involved in the flavonoid metabolic pathway related to pericarp color. These results provide insights into the genetic basis of rice grain color and facilitate genomic breeding to improve appearance and commercial quality of whole grain rice.

Effect of different doses of nitrogen fertilization on bioactive compounds and antioxidant activity of brown rice

Brown rice as a whole grain food is associated with various chronic diseases' reduced risks. In this study, the effects of different doses of nitrogen fertilization (0, 160, 210, 260, 315, and 420 kg N/ 100 m²) on bioactive compounds and antioxidant activity of brown rice (yanfeng47) were investigated. At nitrogen level of 210-260 kg N/100 m², the content of TFC (302.65 mg/100 g), β-sitosterol (1762.92 mg/100 g), stigmasterol (1358.735 mg/100 g), DPPH (74.57%), and OH free radical scavenging (74.19%) was the highest. The major phenolic acid was p-hydroxybenzoic acid. There were significant positive linear relationships between TFC (0.872, 0.843), β-sitosterol (0.896, 0.657), stigmasterol (0.543, 0.771), p-hydroxybenzoic acid (0.871, 0.875), and DPPH, OH antioxidant activity. These indicated that TFC and phytosterols were the most important components in brown rice that had strong antioxidant activity. Composite score of principal components indicated 210 Kg N/100 m² exhibited a more ideal dose of nitrogen for nutritional composition and antioxidant activity of brown rice.

Improvement in the metabolic markers of prediabetic subjects due to the partial substitution of Taiken9 rice by RD43 rice in their daily diet: a randomized clinical trial

Although RD43 rice is characterized by high amounts of undigestible starch, its potential health benefits for prediabetic individuals remain unknown. Thus, the effect of regular consumption of RD43 rice on the glycemic response, body composition, and metabolic markers was investigated in a sample of 34 participants with prediabetes (aged from 32 to 68 years) who were randomly allocated to either the treatment or the control group. The first were required to consume RD43 rice (Glycemic Index [GI] = 78) containing 14.1 g of undigestible starch daily as a substitute for two meals per day while the second were given the Taiken9 rice (GI = 98) for 12 continuous weeks. The evaluations were performed at baseline, at the end of week 6 and 12, and at follow-up conducted two weeks after the intervention had ended. The results obtained at the week 12 assessment clearly showed a significant decrease in fasting plasma glucose, insulin, HbA1c, and HOMA-IR in the group that consumed RD43 rice. In addition, daily ingestion of RD43 rice markedly reduced body weight, Body Mass Index (BMI), total fat mass, and waist circumference at both week 6 and 12 compared with the baseline. When compared with the controls, the treatment group also exhibited a significant decrease in fasting plasma insulin and HOMA-IR at week 12. However, no significant inter- or intra-group differences in lipid profiles were detected. These findings suggest that RD43 rice could be a potential staple food with the capacity to improve glycemic control and body composition in prediabetic individuals.

Marker-Assisted Backcrossing (MABc) to Improve Eating Quality with Thin Seed Coat and Aleurone Layer of Non-Glutinous Japonica Variety in Rice

Brown rice is composed of rice bran, pericarp, seed coat, and aleurone layers, and the rice bran layer contains a large number of substances useful for the human body, such as dietary fiber, α-tocopherol, α-tocotrienol, and vitamins. However, more than 90% of these substances are removed when polished, and white rice has the disadvantage of losing food-related ingredients, such as umami-related amino acids, when compared to the unpolished group. In this study, we tried to develop new breeding lines with a thinner seed coat and aleurone layer to provide high eating quality with softer chewing characteristics and processability in rice grain. We detected an SNP for foreground selection for the backcross population by comparing genome sequences between Samgwang and Seolgaeng and developed high eating quality brown rice breeding lines by applying marker-assisted backcrossing (MAB_C) breeding programs to backcross populations between Samgwang and Seolgaeng using KASP markers. SNP markers for foreground selection were identified to improve eating and processability through SNP mapping of Samgwang and Seolgaeng with SSIIa as a target gene in this study. Line selection according to genotype of KASP markers was successful in BC₁F₁ and BC₂F₁ generations, with the recurrent parent genome recovery ratio ranging from 91.22% to 98.65%. In BC₂F₁ seeds of the selected lines, thickness of the aleurone layer was found to range from 13.82 to 21.67 μm, which is much thinner than the 30.91 μm of the wild type, suggesting that selection by MABc could be used as an additional breeding material for the development of highly processed rice varieties. These lines will be useful to develop new brown rice varieties with softer chewing characteristics and processability in rice grain.

Opportunities for diet quality improvement: the potential role of staple grain foods

OBJECTIVE

Given the high disease burden associated with the low intake of whole grains, modelling studies that estimate the impact of dietary strategies to increase more healthful grain foods consumption are essential to inform evidence-based and culturally specific policies. The current study investigated the potential nutritional impact of replacing staple grain foods with more healthful options.

DESIGN

Based on the 2015 Health Survey of São Paulo, a cross-sectional, population-based study, we modelled the substitution of white rice and white bread with brown rice and whole-wheat bread. Outcomes included changes in more healthful grain foods, energy and nutrient intakes.

SETTING

Urban area of São Paulo, Brazil.

PARTICIPANTS

Participants aged over 12 years who completed a semi-structured questionnaire and one 24-h recall (n 1741).

RESULTS

The substitution of all white rice and white bread with brown rice and whole-wheat bread, respectively, would result in more than 5 % increases in Zn (+9·1 %), Ca (+9·3 %), vitamin E (+18·8 %), dietary fibre (+27·0 %) and Mg (+52·9 %) intake, while more than a 5 % decrease would be seen for total carbohydrate (-6·1 %), folate (-6·6 %), available carbohydrate (-8·5 %), Fe (-8·6 %), vitamin B6 (-12·5 %), vitamin B2 (-17·4 %), and vitamin B1 (-20·7 %). A substantial increase in the amount of more healthful grain foods consumed would be seen (10 g/d to 220 g/d, or from 4 % to 69 % of total grain intake).

CONCLUSIONS

Replacing white rice and white bread with their whole-grain versions has the potential to improve diet quality, suggesting they are prime targets for policy actions aiming at increasing intake of more healthful grain foods.

Ready to eat shelf-stable brown rice in pouches: effect of moisture content on product's quality and stability

Despite several nutritional benefits of brown rice (BR) its consumption remains limited compared to white rice. Two of the major barriers to its consumption are long cooking time and limited shelf life. However, those two hurdles can be overcome through the development of shelf-stable BR pouches to create new ready-to-eat (RTE) products, a food category that is gaining important market shares. Nevertheless, scarce information is available on the production and shelf-life stability of ready-to-eat BR products. The first objective of this study was the determination of the optimal moisture range to fully cook BR. The second objective was to determine the effect of moisture content and storage time on two fundamental parameters for consumer's acceptance of rice: color and texture. Three RTE BR pouches with moisture contents of 54%, 57% and 60% were produced and texture and color were evaluated after 1 year of storage. Significant changes in hardness and stickiness were reported during long-term storage. Moisture content negatively affected hardness and positively affected stickiness. Furthermore, storage time and moisture showed a significant effect on rice color. The present results provide information that will be useful to design new RTE meals to promote brown rice consumption.