Rice-Endosperm and Rice-Bran Proteins: A Review

Investigation of standardized ileal amino acid digestibility of rice protein meal in sexed broilers

Rice protein meal (RPM), a byproduct of the rice industry, has emerged as a potential alternative for poultry feed, especially in rice-producing regions in the South Asia region. The aim of this study was to evaluate the standardized ileal amino acid (AA) digestibility of RPM produced from two distinct rice varieties in sexed broiler chickens, with or without the inclusion of a commercial protease enzyme. Treatments were structured in a 2 × 2 × 2 factorial arrangement, including two sources of RPM (Basmati and IRI), sex (male and female), and protease levels (0 and 500 units per ton of feed). In addition to the test diets, a reference diet based on soybean meal (SBM) and a nitrogen-free diet (NFD) were included in the experiment. Titanium dioxide was added on 0.30% of the diets as an inert marker. Experimental diets were fed to 6 replicates, each consisting of male and female chicks, from 21 to 28 days of age. The data were analyzed using General Linear Model techniques with the help of SPSS 16.0. The main effect of varieties was significant (P < 0.05), as the standardized ileal digestibility (SID) of lysine (57.8%) and threonine (50.7%) was higher for Basmati compared to IRI. The SID for arginine was lower (P = 0.02), and the SID of cysteine (14.4%), isoleucine (47.3%), leucine (46.1%), valine (45.2%), and histidine (49.6%) tended to be lower (P < 0.07) in females for RPM derived from Basmati rice. Protease had no effect on the SID of AA, nor did any of the other three- or two-way interactions.

Rice bran as a potent ingredient: unveiling its potential for value-added applications

Rice bran production significantly contributes to global environmental deterioration, yet its potential remains underutilized. This review discusses the nutritional composition, bioactive compounds, health benefits, limitations, and potential application of rice bran in both food and non-food sectors. While minor variations exist between pigmented and non-pigmented rice bran, the former is abundant in phytochemicals, which offer therapeutic benefits. The primary limitations hindering rice bran's food application include rancidity, toxic heavy metals, and antinutrients. Effective stabilization is crucial to extend rice bran's shelf life. Despite these challenges, rice bran holds significant potential for value-added products. Hence, its rich composition and diverse applications underscore its importance as a valuable resource for sustainable production practices.

Investigating the triple-frequency ultrasound-assisted fermented rice lees: Impact on physicochemical, structural, morphological, and metabolic properties

This study examined the effect of triple-frequency ultrasound treatment (TFUT)-assisted lactic acid bacteria (LAB-L. plantarum and L. helveticus fermentation for 24-h and 48-h) on the chemical, structural, morphological, metabolic, and sensory properties of rice lees (RL). Ultrasonicated-assisted RL fermented with L. helveticus (URLH-48) had the greatest total phenolic contents (TPC) (112.1 mg GAE/m), total flavonoid contents (TFC) (163.62 mg RE/mL), and proanthocyanidin contents (PAC) (728.34 mg/mL) compared to RL (control) and other treatments. Furthermore, URLH-48 demonstrated an increase in the concentrations of quinic acid (486.96 mg/L) and gallic acid (201.42 mg/L), as determined by HPLC-UV analysis. Additionally, FTIR spectral analyses demonstrated that TFUT-assisted fermented RL exhibited a greater degree of flexibility and mobility in its secondary structures compared to RL (control). The amino acid's profile of RL was significantly increased as LAB degraded the RL proteins, and the function of TFUT facilitates bacterial activity. Moreover, SEM observation provides convincing evidence that TFUT improves and speeds up the breakdown of proteins' structures, resulting in irregular and dense structures. Correlation and molecular docking research suggest that TFUT has different impacts on specific RL and fermented RL characteristics. The analyses conducted using GC-MS and E-nose indicated the generation of highly volatile flavor compounds through fermentation. The sensory evaluation results show an increase in liking following fermentation and TFUT-assisted fermentation, which is attributed to the production of flavor compounds. Consequently, the combined use of TFUT-assisted fermentation markedly improves the polyphenolic composition, antioxidant capacity, flavor profile, micromorphology, and overall quality of RL, which may enhance their functionality and broaden their applications in the food industry.

Optimizing Printability of Rice Protein-Based Formulations Using Extrusion-Based 3D Food Printing

The purpose of this study was to investigate the application of an innovative extrusion-based 3D food printing (3DFOODP) technique in developing rice protein-starch (RP-S) gel-based products. The effects of 3DFOODP conditions were examined, which included variations in the concentrations of rice protein (RP) and corn starch (S) (15, 17.5, and 20 wt.%), nozzle size (0.8, 1.5, and 2.5 mm), printing temperature (40°C, 60°C, and 80°C), and ingredient flow speed (5.7, 6.3, and 6.9 mL/min). A hollow cylindrical model was chosen as a test object to determine the printability of RP-S gels. The best 3D printability was achieved using an RP concentration of 17.5% and an S concentration of 15% at 60°C printing temperature with a nozzle size of 1.5 mm, and ingredient flow speed of 6.3 mL/min. With increasing the RP concentration, a rise in apparent viscosity, loss, and storage moduli was observed. The recovery test showed the gels' rapid and reversible response. The freeze-dried 3D-printed RP-S gels showed a porous granular structure, depending on the printing temperature. No chemical interactions between the RP and S were observed as analyzed by FTIR. Overall, RP, in combination with S, provides a new opportunity for the 3DFOODP and their utilization by the alternative protein industry.

Improved qualities of cod-rice dual-protein gel as affected by rice protein: Insight into molecular flexibility, protein interaction and gel properties

Blending plant-based proteins with animal-based proteins to achieve adequate dietary protein intake is a strategy to address dietary deficiencies in the elderly. This research systematically investigated the effect of the ratio of cod protein/rice protein (21:0, 21:1.5, 21:3, 21:4.5, 21:6, 21:7.5, and 21:9) on the gelation properties of dual-protein gels and the underlying dual-protein interaction mechanisms. The results indicated that the myosin heavy chain (MHC) of cod and the glutelin in rice protein are primarily linked by hydrogen bonds, particularly involving Tyr residues, as evidenced by molecular docking and fluorescence quenching results. The addition of rice protein in cod protein promoted α-helix transforming into β-sheet, β-turn and random coil of the original protein solution, which was significantly correlated with molecule flexibility increasing. The decrease in the dual-protein particle size, and rice protein uniformly distributed in a cod protein-based gel network, which promoted the compactness and density of the gel structure. It was found that the hardness and springiness of 21:6 cod-rice protein gel increased by 73.96% and 17.28% compared to single cod gel, respectively. This study provides theoretical basis to the mechanism of dual-protein interaction affecting gel properties from the molecular level.

Effects of enzyme hydrolysis-assisted fibrillation treatment on the solubility, emulsifying properties and antioxidant activity of rice protein

This work aimed to explore the changes of rice protein (RP) in solubility, emulsifying properties, and antioxidant activity after the enzyme hydrolysis-assisted fibrillation dual modification. Results showed that enzyme hydrolysis by papain and fibrillation treatments significantly affected the secondary and tertiary structures of RP. The modified proteins, including RP hydrolysate (RPH), RP nanofibrils (RPN), and RPH nanofibrils (RPHN), demonstrated enhanced solubility and antioxidant activity compared to RP, with RPHN exhibiting the superior performance. The emulsifying capacity of RPH, RPN, and RPHN increased by 9.55 %, 22.86 %, and 26.57 %, respectively, compared to that of RP. Furthermore, RPHN displayed the highest emulsion stability index. Nanoemulsion stabilized by RPHN showed enhanced centrifugal, storage, and oxidative stabilities. Neither RPHN nor RPN exhibited cytotoxicity to human cell lines, and could provide nutrients for cells. Overall, the functional properties and antioxidant activity of RP were significantly improved by enzyme hydrolysis-assisted fibrillation dual modification. This study may provide reference for the development and utilization of nanofibrils from plant proteins.

Proteins from Legumes, Cereals, and Pseudo-Cereals: Composition, Modification, Bioactivities, and Applications

This review presents a comprehensive analysis of plant-based proteins from soybeans, pulses, cereals, and pseudo-cereals by examining their structural properties, modification techniques, bioactivities, and applicability in food systems. It addresses the critical need for a proper utilization strategy of proteins from various plant sources amidst the rising environmental footprint of animal protein production. The inherent composition diversity among plant proteins, their nutritional profiles, digestibility, environmental impacts, and consumer acceptance are compared. The innovative modification techniques to enhance the functional properties of plant proteins are also discussed. The review also investigates the bioactive properties of plant proteins, including their antioxidant, antimicrobial, and antitumoral activities, and their role in developing meat analogs, dairy alternatives, baked goods, and 3D-printed foods. It underscores the consideration parameters of using plant proteins as sustainable, nutritious, and functional ingredients and advocates for research to overcome sensory and functional challenges for improved consumer acceptance and marketability.

Rice lipases: a conundrum in rice bran stabilization: a review on their impact and biotechnological interventions

Rice is a primary food and is one of the most important constituents of diets all around the world. Rice bran is a valuable component of rice, containing many oil-soluble vitamins, minerals, and oil. It is known for its ability to improve the economic value of rice. Further, it contains substantial quantities of minerals like potassium, calcium, magnesium, iron and antioxidants like tocopherols, tocotrienols, and γ-oryzanol, indicating that rice bran can be utilized effectively against several life-threatening disorders. It is difficult to fully utilize the necessary nutrients due to the presence of lipases in rice bran. These lipases break down lipids, specifically Triacylglycerol, into free fatty acids and glycerol. This review discusses physicochemical properties, mechanism of action, distribution, and activity of lipases in various components of rice seeds. The phylogenetic and gene expression analysis helped to understand the differential expression pattern of lipase genes at different growth phases of rice plant. Further, this review discusses various genetic and biotechnological approaches to decrease lipase activity in rice and other plants, which could potentially prevent the degradation of bran oil. The goal is to establish whether lipases are a major contributor to this issue and to develop rice varieties with improved bran stability. This information sets the stage for upcoming molecular research in this area.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01343-3.

Cereal bran proteins: recent advances in extraction, properties, and applications

The projected global population is expected to reach around 9.7 billion by 2050, indicating a greater demand for proteins in the human diet. Cereal bran proteins (CBPs) have been identified as high-quality proteins, with potential applications in both the food and pharmaceutical industries. In 2020, global cereal grain production was 2.1 billion metric tonnes, including wheat, rice, corn, millet, barley, and oats. Cereal bran, obtained through milling, made up 10-20% of total cereal grain production, varying by grain type and milling degree. In this article, the molecular composition and nutritional value of CBPs are summarized, and recent advances in their extraction and purification are discussed. The functional properties of CBPs are then reviewed, including their solubility, binding, emulsifying, foaming, gelling, and thermal properties. Finally, current challenges to the application of CBPs in foods are highlighted, such as the presence of antinutritional factors, low digestibility, and allergenicity, as well as potential strategies to improve the nutritional and functional properties by overcoming these challenges. CBPs exhibit nutritional and functional attributes that are similar to those of other widely used plant-based protein sources. Thus, CBPs have considerable potential for use as ingredients in food, pharmaceutical, and other products.

Deciphering the structural and functional characteristics of an innovative small cluster branched α-glucan produced by sequential enzymatic synthesis

Highly branched α-glucan (HBAG) proved to be a promising material as an osmotic agent in peritoneal dialysis solutions. However, high resistance of HBAG to amylolytic enzymes might be a potential drawback for peritoneal dialysis due to its high degree of branching (20-30 %). To address this issue, we designed a small-clustered α-glucan (SCAG) with a relatively low molecular weight (Mw) and limited branching. Structural characteristics revealed that SCAG was successfully synthesized by modifying waxy rice starch (WRS) using sequential maltogenic α-amylase (MA) and starch branching enzyme (BE). The Mw of SCAG was 1.40 × 10⁵ Da, and its (α1 → 6) bonds ratio was 8.93 %, which was below that of HBAG. A relatively short branch distribution was observed in SCAG (CL = 6.27). Short-range orderliness of WRS was reduced from 0.749 to 0.322 with the MABE incubation. Additionally, SCAG had an extremely low viscosity (~12 cP) and nearly no retrogradation. Although the resistance of SCAG to amylolytic enzymes was enhanced by 15.22 % compared with native WRS, the extent was significantly lower than that of HBAG in previous studies. These new findings demonstrate the potential of SCAG as a novel functional α-glucan in food and pharmaceutical applications.

Alanine Substitution to Determine the Effect of LR5 and YR6 Rice Peptide Structure on Antioxidant and Anti-Inflammatory Activity

The relationship between the structure of peptides LR5 (LHKFR) and YR6 (YGLYPR) and their antioxidant and anti-inflammatory activity remains unclear. Herein, leucine, tyrosine, proline, and phenylalanine at different positions in the peptides were replaced by Alanine (Ala), and two new pentapeptides (AR5 and LAR5) and four hexapeptides (AGR6, YAR6, YLR6, and YGR6) were obtained. The effect of Ala replacement on the hydrophobicity, cytotoxicity, NO inhibition rate, and active oxygen radical scavenging ability of these peptides and their antioxidant and anti-inflammatory abilities were investigated. The results indicated that the hydrophobicity of the peptides was associated with their amino acid composition and their specific sequence. However, hydrophobicity had no significant effect on cytotoxicity. Ala replacement was shown to enhance hydrophobicity and consequently increased the antioxidant and anti-inflammatory activity of the peptides. The molecular docking studies indicated that the amino acid interactions of the peptide with the Keap1 protein influenced the hydrophobicity and thus affected the antioxidant activity of the peptide.

High Value Compounds and Bioactivity of Rice Bran, Rice Bran Protein: A Review

Rice bran and rice bran protein are important sources of minerals, energy, and vitamins. Other bioactive compounds are abundantly available to exert therapeutical activity. Healthpromoting activities of high-value compounds of rice bran were significant, as observed in recent studies. A variety of bioactive components present in rice bran and rice bran extract are responsible to exhibit therapeutical potential like chemopreventive, cardioprotective, hepatoprotective, immunomodulatory, neuroprotective, and lipid-lowering activity. Several bioactivity representative compounds like γ-oryzanol, ferulic acid, caffeic acid, tricin, protocatechuic acid, vanillic acid, coumaric acid, phytic acid, isoferulic acid, gallic acid, γ-amino butyric acid, sinapic acid, saturated and unsaturated fatty acids, vitamin E complexes, β-sitosterol, stigmasterol, campesterol, cyanidin-3-glucoside, peonidin-3-glucoside, quercetin, rutin, kaemferol, β-carotene, lutein, vitamin B and lycopene are known to display significant health benefits. The bioactive components produced therapeutical effects by regulation of different mechanisms like increasing faecal excretion, reducing oxidative stress, reducing the level of malondialdehyde (MDA), regulation of NF-kb activation, reduction of proinflammatory cytokines production, suppression of SREBP-1, reduction in the expression of anti-apoptotic protein Bcl-2, elevated the expression of proapoptotic protein Bax, up-regulating P53 expression and suppressing COX-2. Several research engines like PubMed, google scholar, science direct, etc. were used to collect the data on the mentioned keywords. Recent scientific works were included in this article. In this review paper, we profiled the high-value compounds and focused on their antioxidant, anti-hyperlipidemic, antidiabetic, and anticancer activity with their possible mechanism of action.

Scientific substantiation of the use of plant processing derivatives for enrichment of ferrous milk drinks

Derivatives from plant processing are generally classified as industrial waste. Despite their biological properties, they are mostly recycled or used in the production of animal feed. Given the rapid growth of the world's population and the increased interest of consumers in plant foods, it is advisable to use plant by-products as nutritional supplements with certain functional properties. The purpose of the study is to substantiate the possibility of using sesame flour and rice bran as fillers in the production of fermented milk drinks. Formulas were developed for fermented milk drinks enriched with sesame flour in the amount of 2 % and rice bran – 1 %. The amount of additives was determined taking into account the optimal organoleptic indicators. The study showed that the addition of additives increased the content of dietary fiber in a product enriched with rice bran, up to 0.3%, and up to 0.7 % in a fermented milk drink with sesame flour. The antioxidant properties of a fermented milk drink enriched with sesame flour were studied. Antioxidant properties were determined by the level of DPPH radical scavenging activity. The results of the study showed that the highest DPPH radical scavenging activity (1.82 mg/ml) was observed in the enriched sample on day 7 of storage. On the 14th day of storage in the control sample, the activity decreased to 1.55 mg/ml, while in the sample with sesame flour its value was at the level of 1.75 mg/ml. Thus, it can be argued that the investigated plant by-products can be used as additives to increase the content of dietary fiber and increase the shelf life of products

A Narrative Review on Rice Proteins: Current Scenario and Food Industrial Application

Rice, Oryza sativa, is the major staple food that provides a larger share of dietary energy for more of the population than other cereal crops. Moreover, rice has a significant amount of protein including four different fractions such as prolamin, glutelin, globulin, and albumin with different solubility characteristics. However, these proteins exhibit a higher amino acid profile, so they are nutritionally important and possess several functional properties. Compared with many other cereal grains, rice protein is hypoallergic due to the absence of gluten, and therefore it is used to formulate food for infants and gluten-allergic people. Furthermore, the availability makes rice an easily accessible protein source and it exhibits several activities in the human body which discernibly affect total health. Because of these advantages, food industries are currently focusing on the effective application of rice protein as an alternative to animal-based and gluten-containing protein by overcoming limiting factors, such as poor solubility. Hence, it is important to gain an in-depth understanding of the rice protein to expand its application so, the underlined concept of this review is to give a current summary of rice protein, a detailed discussion of the chemistry of rice protein, and extraction techniques, and its functional properties. Furthermore, the impact of rice protein on human health and the current application of rice protein is also mentioned.

Industrially Produced Rice Protein Ameliorates Dextran Sulfate Sodium-Induced Colitis via Protecting the Intestinal Barrier, Mitigating Oxidative Stress, and Regulating Gut Microbiota

Inflammatory bowel disease (IBD) poses a threat to health and compromises the immune system and gut microflora. The present study aimed to explore the effects of rice protein (RP) purified from rice dregs (RD) on acute colitis induced by dextran sulfate sodium (DSS) and the underlying mechanisms. Results showed that RP treatment could alleviate the loss of body weight, colon shortening and injury, and the level of disease activity index, repair colonic function (claudin-1, ZO-1 and occludin), regulate inflammatory factors, and restore oxidative balance (malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and total antioxidant capability (T-AOC)) in mice. Also, RP treatment could activate the Kelch-like ECH-associating protein 1 (Keap1)-nuclear factor E2-related factor 2 (Nrf2) signaling pathway, mediate the expression of downstream antioxidant protease (NQO-1, HO-1, and Gclc), regulate gut microbiota by enhancing the relative abundance of Akkermansia and increasing the value of F/B, and adjust short-chain fatty acid levels to alleviate DSS-induced colitis in mice. Thus, RP may be an effective therapeutic dietary resource for ulcerative colitis.

Enzymatic Hydrolysis of Broken Rice Protein: Antioxidant Activities by Chemical and Cellular Antioxidant Methods

Excessive reactive oxygen species (ROS) is an important cause of aging, and supplementing antioxidants through diet is one of the important ways to delay aging. Some studies have confirmed that rice protease hydrolysate has antioxidant activity, but was rarely been investigated on cells. Thus, commercial enzymes, alkaline enzyme, neutral enzyme, pepsin, chymotrypsin, and trypsin were selected to hydrolyze broken rice protein (BRP) to obtain the corresponding hydrolysates, which were A-broken rice protein hydrolysate (BRPH), N-BRPH, P-BRPH, C-BRPH, and T-BRPH, respectively. Then the antioxidant properties of BRPHs were evaluated by different chemical and cellular antioxidation. Molecular weight, peptide length distribution, and amino acid sequence were detected to insight into the antioxidant properties. Among BRPHs, the A-BRPH displayed the strongest hydroxyl radical scavenging activity (IC50 = 1.159 mg/ml) and metal ion-chelating activities (IC50 = 0.391 mg/ml). Furthermore, cellular antioxidation confirmed that A-BRPH significantly increased cell viability and inhibited the intracellular ROS release in both aging cells and cell-aging processes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results revealed that peptides with molecular weight <14.5 KDa were produced by enzymatic hydrolysis. Additionally, A-BRPH rich in low molecular weight (<3 kDa) and short-length peptides with some specific amino acids, such as aromatic and hydrophobic amino acids, contributes to the antioxidant properties. This study provided theoretical to the utilization of broken rice and confirmed that A-BRPH could be used in new anti-aging food and health products for human consumption.

Novel Angiotensin-I Converting Enzyme Inhibitory Peptides Isolated From Rice Wine Lees: Purification, Characterization, and Structure-Activity Relationship

The bioactive peptides that can inhibit angiotensin-I converting enzyme (ACE, EC. 3. 4.15.1) are considered as possible cures of hypertension. Food-derived angiotensin-I converting enzyme inhibitory (ACEi) peptides have gained more attention because of their reduced side effects. In this study, we reported the method for purifying ACEi peptides from the lees of traditional Chinese rice wine and evaluated the product's biochemical properties. After three steps of reversed-phase high-performance liquid chromatography (RP-HPLC), for the first time, we isolated, purified, and identified two novel peptides: LIIPQH and LIIPEH, both of which showed strong ACEi activity (IC₅₀-values of 120.10 ± 9.31 and 60.49±5.78 μg/ml, respectively). They were further categorized as mixed-type ACE inhibitors and were stable against both ACE and gastrointestinal enzymes during in vitro digestion. Together, these results suggest that the rice wine lees that produced as a by-product during rice wine production can be utilized in various fields related to functional foods and antihypertensive medicine.

Proteins in Food Systems-Bionanomaterials, Conventional and Unconventional Sources, Functional Properties, and Development Opportunities

Recently, food companies from various European countries have observed increased interest in high-protein food and other products with specific functional properties. This review article intends to present proteins as an increasingly popular ingredient in various food products that frequently draw contemporary consumers' attention. The study describes the role of conventional, unconventional, and alternative sources of protein in the human body. Furthermore, the study explores proteins' nutritional value and functional properties, their use in the food industry, and the application of proteins in bionanomaterials. Due to the expected increase in demand for high-protein products, the paper also examines the health benefits and risks of consuming these products, current market trends, and consumer preferences.

An overview on antioxidant peptides from rice bran proteins: extraction, identification, and applications

Rice by-products, generated through the milling processes, have recently been recognized as a potential source of bioactive compounds, such as proteins, essential amino acids, and phenolics. Owing to their antioxidant capacity (which improve the storage stability of foods), these compounds have gained much attention because of their beneficial impacts on human health. It has to be noted that large quantities of rice by-products are not efficiently utilized, which may result in industrial wastes and environmental consequences. Thence, the aim of this review is to provide a comprehensive insight on the antioxidant capabilities, extraction, identification, functional attributes, and applications of bioactive hydrolysates and peptides derived from rice bran protein. This overview would provide an insight on rice bran proteins, which are abundant in bioactive peptides, and could be used as value-added products in food and pharmaceutical applications. Inclusion of bioactive peptides to prevent food spoilage while maintaining food safety has also been highlighted.

High-Value Compounds in Fruit, Vegetable and Cereal Byproducts: An Overview of Potential Sustainable Reuse and Exploitation

Food waste (FW) represents a global and ever-growing issue that is attracting more attention due to its environmental, ethical, social and economic implications. Although a valuable quantity of bioactive components is still present in the residuals, nowadays most FW is destined for animal feeding, landfill disposal, composting and incineration. Aiming to valorize and recycle food byproducts, the development of novel and sustainable strategies to reduce the annual food loss appears an urgent need. In particular, plant byproducts are a plentiful source of high-value compounds that may be exploited as natural antioxidants, preservatives and supplements in the food industry, pharmaceuticals and cosmetics. In this review, a comprehensive overview of the main bioactive compounds in fruit, vegetable and cereal byproducts is provided. Additionally, the natural and suitable application of tailored enzymatic treatments and fermentation to recover high-value compounds from plant byproducts is discussed. Based on these promising strategies, a future expansion of green biotechnologies to revalorize the high quantity of byproducts is highly encouraging to reduce the food waste/losses and promote benefits on human health.