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Summary: The market for rice protein (RP) has been steadily growing, but applications of RPs as food ingredients and functional materials are limited due to poor solubility in water. Here, the complex of RP and isolated soy protein (ISP) was prepared, and the potential utility of RP–ISP complex as an emulsifier was evaluated. The solubility of the RP solution was 25.8% whereas it was greatly increased to 68.4% in the RP–ISP complex. The properties of RP and RP–ISP complex were assessed by scanning electron microscope, gel electrophoresis, circular dichroism, and surface hydrophobicity test. Next soybean oil emulsions were prepared using the RP and RP–ISP complex. The RP‐stabilised emulsion was unstable to storage. In contrast, the RP–ISP complex‐stabilised emulsions showed good stability, especially when more than 0.2% ISP was added. These data suggest that the preparation of soluble RPs by ISP could expand the applications of RP in the food industry. [ABSTRACT FROM AUTHOR]

Leguminous and cereals are an important source of proteins actually having a large presence in the food industry; although, in recent years, there has been an increment in the use of pseudo cereals like quinoa. These types of proteins had shown physical properties could be taken as an advantage in developing new products. Hydrolysis is a process that enhance bio-active and functional attributes and that is why present research worked monitoring the hydrolysis process on proteins using infrared mid-range spectroscopy, to determine such structural changes. Enzymatic hydrolysis with endo or exo-protease, was made on three isolate proteins using Alcalasa® 2,4 L and Flavorzyme® from Sigma Laboratories. Correlation between enzyme/substrate was 5 %. Degree of Hydrolysis (DH) of 46 and 38,4 % were obtained for quinoa and rice isolate, respectively. Both, quinoa and soy hydrolysis monitoring took 60minutes with Alcalasa® 2,5 L, and 120 minutes con Flavorzima®. There were no significant differences of hydrolysis degree at 80 minutes after procedure. As a comparative view protein isolates and their hydrolysis were studied under 4000 cm-1 to 600 cm-1 infrared range to obtain information about the protein structure. Spectre deconvolution technique was applied through Fourier transform. Results showed significant differences on the secondary protein structure when compared to each configuration area. More relevant changes were observed on structural formation of β-sheet and β-turns structures. For an appropriate control of hydrolysis process will have repercussions over a steady protein, that might be used for developing new products. [ABSTRACT FROM AUTHOR]

Summary: The proteins in the raw materials affect the formation of flavour during fermentation. Among all the fermentation broth of protein fraction in the study, the rice prolamin and albumin effectively promoted floral, honey and fruity characteristics in fermentation with higher level of β‐phenylethyl alcohol, 2,4‐dimethyl‐benzaldehyde and ethyl hexadecanoate than those in the fermentation of globulin and glutelin; albumin is with higher level of higher alcohols, but higher alcohols are not good for health because of their acute toxicity and neurotoxic effects. In a further fermentation experiment of addition of prolamin, extra prolamin significantly promoted the formation of aroma volatiles, especially medium and long fatty acid esters and β‐phenylethyl alcohol and its acetate, and the content of β‐phenethyl acetate in sweet rice wine with added prolamin was more than twice that of single sweet rice wine. This study demonstrates that the different rice protein components significantly affect the volatiles generated by microorganism metabolism to impact the flavour of sweet rice wine, and the flavour quality of sweet rice wine can be enhanced by increasing the prolamin content. [ABSTRACT FROM AUTHOR]

Microparticles loaded with rice bran oil were produced by spray drying. Rice flour (RF) and rice protein (RP), considered as co-products of the cereal production chain, were tested as stabilizers in the encapsulation process to improve emulsion stability and the properties of the particles. Rice bran oil presented 1.75% ɣ-oryzanol, a powerful antioxidant with health benefits. AG/RP treatment (10% of rice protein): no phase separation after 24 h, higher zeta potential (-29.09 mV ± 0.67), encapsulation efficiency (73.90% ± 0.22), real density (1.27 g/cm−3), and smaller particle size (8.27 μm ± 0.13). Microparticles containing co-products were the most appropriate to slow down the autooxidation (at 60°C for 8 weeks), especially associated with the use of rice flour. The co-products improve the emulsion characteristics, particle properties and stability of the encapsulated oil. This study presented the technological effects of the use of rice chain co-products, which is in line with the current scenario of sustainability. [ABSTRACT FROM AUTHOR]

Oxidized low-density lipoprotein (ox-LDL) is an inducer of inflammation. To elucidate the link of depression of ox-LDL accumulation and anti-inflammatory function of rice protein (RP) whether dependent on methionine availability, growing and adult rats were fed RP and methionine-supplemented RP (RM) under cholesterol-enriched dietary condition. After two weeks feeding, RP and RMs exerted the anti-inflammatory effects through up-regulating IL-10, while RP and RMs significantly reduced ox-LDL levels and effectively suppressed the expressions of inflammatory mediators (COX-2, IL-1β, IL-6, TNF-α, iNOS). The anti-inflammatory molecular mechanism was to inhibit NF-κB activation and to simulate methionine sulfoxide reductase expression. Results showed, under cholesterol-enriched dietary condition, the anti-inflammatory action can be induced by RP and enhanced by methionine in growing and adult rats. The present study reveals a link of the decreased ox-LDL accumulation with the anti-inflammatory function of RP, which is dependent on methionine availability and independent of dietary cholesterol. [ABSTRACT FROM AUTHOR]

Modification of plant-based protein for promoting wide applications is of interest to the food industry. Rice protein from rice residues was modified by homogenization, and its effect on pasting properties (including gelatinization and rheology) of rice starch was investigated. The results showed that homogenization could significantly decrease the particle size of rice protein and increase their water holding capacity without changing their band distribution in SDS-PAGE. With the addition of protein/homogenized proteins into rice starch decreased peak viscosity of paste. The homogenized proteins decreased breakdown and setback value when compared with that of original protein, indicating homogenized protein might have potential applications for increasing the stability and inhibiting short-term retrogradation of starch paste. The addition of protein/homogenized proteins resulted in a reduction in the viscoelasticity behavior of starch paste. These results indicate that homogenization would create a solution to alter the physicochemical properties of plant proteins, and the homogenized proteins may be a potential candidate for development of protein-rich starchy products. [ABSTRACT FROM AUTHOR]

Rice protein, stands out as a high-quality plant-based protein, suitable for dietary supplementation and food processing. Traditional methods, involving alkaline extraction and acid precipitation, are challenged by the extensive use of chemicals and the difficulty in desalination. This study proposed a novel separation method that utilizes ceramic membranes for direct alkali filtration, eliminating the formation of salts by acid neutralization. The membrane pore size and the operating parameters such as transmembrane pressure, cross-flow velocity, and pH were optimized to enable a high flux (>80 L m−2·h−1) and favorable protein rejection (>95 %) while permitting the removal of excess alkali. Additionally, the effects of non-protein substances, e.g., starch, present in the alkaline extract on the separation performance were explored. Subsequently, an optimized strategy for starch removal was proposed, involving the concentration of the alkali extract using an ultrafiltration membrane, followed by enzymatic hydrolysis of starch and diafiltration to eliminate the residuals of starch hydrolysates and alkali. Under stabilization of protein particles by carboxymethyl cellulose, rice protein with a uniform particle size of 25 nm and a purity of over 80 % was produced. The direct removal of alkali from alkali extracts of rice by ceramic membranes presents a promising strategy for producing rice protein with high purity and reduced aggregation degree, enabling better functionalities such as solubility than the conventional alkali-extraction and acid-precipitation method. [Display omitted] • An acid-free approach was proposed for the extraction and purification of rice protein. • Ceramic ultrafiltration membrane exhibited a high rejection of protein and a high stable flux. • Rice protein with a uniform particle size of 25 nm and a purity level exceeding 80 % was obtained. [ABSTRACT FROM AUTHOR]

An antioxidant amyloid fibril was prepared as an emulsifier by fibrillating limited enzymatic hydrolysis-modified rice protein (HRP). The purpose of this study was to investigate the feasibility of using fibrillated HRP to stabilize oil-in-water emulsion. A free radical scavenging assay revealed that the antioxidant activity of fibrillated HRP was 2.09 times higher than that of native rice protein. Fibrillated HRP demonstrated a marked reduction in interfacial tension, increased surface hydrophobicity and contact angle (> 80°), and rapid adsorption to the interface, with 35.34 ± 2.43% interfacial adsorbed protein content. The fibrillated HRP barriers resisted environment stresses such as NaCl, pH variations, long-term storage, while reducing lipid oxidation degree. Additionally, fibrillated HRP-based emulsion was more effective in protecting β-carotene from degradation compared to other samples. These findings provide theoretical support for the development of rice protein-based antioxidant emulsifiers and modification of emulsifying properties of plant proteins. • Amyloid fibril from rice protein hydrolysate (HRP) served as efficient stabilizer. • Fibrillation improved the interfacial properties and antioxidant activity of HRP. • Fibrillated HRP enhanced the physical and lipid oxidation stability of emulsion. • β-Carotene had the highest processing stability in fibrillated HRP-based emulsion. • Fibrillated HRP-based emulsion impacted the digestive properties of β-carotene. [ABSTRACT FROM AUTHOR]

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. • Dual modification enhanced the antioxidant activity of rice protein (RP). • Emulsifying properties and solubility of RP were improved by dual modification. • Nanoemulsions stabilized by RPHN showed higher stability than other emulsions. [ABSTRACT FROM AUTHOR]

The functionality (e.g., emulsifying ability) of rice protein (RP) is restricted largely by its low solubility. The formation of a co-assembly with RP and an exogenous protein through pH-cycle is one promising method, but the mechanism behind this has not been revealed. This study utilized ovalbumin (OVA) to improve the solubility of RP and investigated the effect of OVA on the physicochemical characteristics of RP, the interactions between RP-OVA co-assembly and water, the RP-OVA interactions, the key subunits related to the solubility improvement of RP, and the emulsifying capacity of the co-assembly. The formation of RP-OVA co-assembly considerably improved the solubility of RP (up to 73.12%), and the multi-level structure and surface property of RP were altered by OVA. The mechanism for the solubility increase was the hydrophobic interactions between OVA and RP, resulting in the exposure of some hydrophilic amino acids to protein surface and further generating a low surface hydrophobicity that allow more water molecules to permeate. Eight subunits in RP were critical for its solubility increase. The RP-OVA co-assembly prepared in this study showed an emulsifying ability even better than whey protein isolate (a commercial emulsifier) in high internal phase emulsion. This study may guide the solubility improvement of RP and widen the application of RP in the food industry as an emulsifier. [Display omitted] • The solubility of RP was greatly improved after co-assembling with OVA via a pH-cycle. • The RP-OVA co-assembly formed a real protein solution. • The presence of OVA changed the multi-level structure and surface property of RP. • The potential mechanism of the increased solubility of OVA-RP co-assembly was proposed. • The OVA-RP co-assembly showed a better emulsifying ability than whey protein isolate. [ABSTRACT FROM AUTHOR]

Rice wine is a traditional beverage in Asian countries, and rice wine lees, a by-product resulting from the fermentation process, generate substantial amounts annually. To promote the sustainable utilization of such product, this research presents the optimization of rice protein extraction processes. An optimized alkaline extraction process (pH 12, 45 °C, 6 h and solid-liquid ratio 1:8), and an optimized carbohydrate-lipid removal process (α-amylase plus cellulase for a 2-h reaction at pH 5 and 50 °C, then heating to 60 °C for 1 h; followed by lipid removal twice at 50 °C for 3 h) were established, resulting in a protein content of 70.80% and 82.52%, respectively. FT-IR and SDS-PAGE indicated a prevalence of β-sheet and α-helix structures in both protein products, and analogous protein subunits, but protein product post carbohydrate-lipid removal showcased superior stability and orderliness. Functional properties and in vitro digestion studies indicated that alkaline extraction improved solubility, foaming ability, emulsifying ability and gastrointestinal digestibility, but presented lower oil-holding capacity, foam stability and emulsion stability. These findings suggest that carbohydrate-lipid removal process is an efficacious technique for extracting rice protein from rice wine lees. [Display omitted] • RPA protein (70.8% protein) was from rice wine lees (RWL) via alkaline extraction. • RPE protein (82.5% protein) was from RWL via carbohydrate-lipid removal process. • Both had high β-sheet/α-helix contents and different foaming/emulsifying properties. • RPA had higher solubility and in vitro gastrointestinal digestibility than RPE. • RPA had lower surface hydrophobicity and oil-holding capacity than RPE. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bromelain is an effective enzyme for increasing the biological activity of Riceberry protein. • Riceberry peptides (<3 kDa) have the potential to serve as functional ingredients. • Antioxidant activity of the encapsulated hydrolysate is similar to that of the freeze-dried hydrolysate. • Cluster dextrin maintains the antioxidant activity of protein hydrolysate. • Cluster dextrin minimizes the degradation of bioactive peptides after digestion. In this work, the biological properties of fractionated Riceberry bran protein hydrolysate obtained by ultrafiltration (URBPH) were evaluated and the possibility of using cluster dextrin to produce hydrolysate powder by spray-drying was investigated. Fractionation into peptides < 3 kDa was observed to improve antioxidant activity. URBPH < 3 kDa was then freeze-dried (FD-URBPH) and spray-dried (SD-URBPH) at different inlet air temperatures of 100–160 °C. The water solubility and antioxidant activity of FD-URBPH were higher than those of SD-URBPH. Nevertheless, encapsulation of hydrolysate with 10% cluster dextrin and an inlet temperature of 120 °C was also successful in maintaining protein qualities, which showed high 2,2′-azino-bis 3-ethylbenzthiazoline-6-sulfonic (ABTS•+) scavenging activity (89.14%) and water solubility index (92.49%) and low water activity (a w = 0.53). Moreover, encapsulation preserved the antioxidant activity of peptides during gastrointestinal digestion better than the free form. URBPH and its spray-dried microcapsules could be used as bioactive ingredients in functional drinks or foods. [ABSTRACT FROM AUTHOR]

Rice flour (RF) has become a promising food material. In the present study, RF with higher protein content was prepared using a granular starch hydrolyzing enzyme (GSHE). Particle size, morphology, crystallinity, and molecular structures of RF and rice starch (RS) were characterized to establish a hydrolytic mechanism; thermal, pasting, and rheological properties were determined to evaluate processability using differential scanning calorimetry (DSC), rapid viscosity analysis (RVA), and rheometer, respectively. The GSHE treatment resulted in pinholes, pits, and surface erosion through sequential hydrolysis of crystalline and amorphous areas on the starch granule surface. The amylose content decreased with hydrolysis time, while the very short chains (DP < 6) increased rapidly at 3 h but decreased slightly later. After hydrolysis for 24 h, the protein content in RF increased from 8.52% to 13.17%. However, the processability of RF was properly maintained. Specifically, the data from DSC showed that the conclusion temperature and endothermic enthalpy of RS barely changed. The result of rapid RVA and rheological measurement indicated that RF paste viscosity and viscoelastic properties dropped rapidly after 1 h hydrolysis and thereafter recovered slightly. This study provided a new RF raw material useful for improving and developing RF-based foods.

In this study, soy isoflavones-loaded nanoparticles were prepared using rice proteins (RPs) hydrolyzed by four types of enzyme (alcalase, neutrase, trypsin, and flavorzyme). After optimizing the preparation conditions, the encapsulation efficiency (EE) of the nanoparticles ranged from 61.16% ± 0.92% to 90.65% ± 0.19%. The RPs that were hydrolyzed by flavorzyme with a molecular weight of

At least half the population in industrialized countries suffers from obesity due to excessive accumulation of adipose tissue. Recently, rice (Oryza sativa) proteins have been considered valuable sources of bioactive peptides with antiadipogenic potential. In this study, the digestibility and bioaccessibility in vitro of a novel protein concentrate (NPC) from rice were determined through INFOGEST protocols. Furthermore, the presence of prolamin and glutelin was evaluated via SDS-PAGE, and their potential digestibility and the bioactivity of ligands against peroxisome proliferator-activated receptor gamma (PPARγ) were explored by BIOPEP UWM and HPEPDOCK. For the top candidates, molecular simulations were conducted using Autodock Vina to evaluate their binding affinity against the antiadipogenic region of PPARγ and their pharmacokinetics and drug-likeness using SwissADME. Simulating gastrointestinal digestion showed a recovery of 43.07% and 35.92% bioaccessibility. The protein banding patterns showed the presence of prolamin (57 kDa) and glutelin (12 kDa) as the predominant proteins in the NPC. The in silico hydrolysis predicts the presence of three and two peptide ligands in glutelin and prolamin fraction, respectively, with high affinity for PPARγ (≤160). Finally, the docking studies suggest that the prolamin-derived peptides QSPVF and QPY (−6.38 & −5.61 kcal/mol, respectively) have expected affinity and pharmacokinetic properties to act as potential PPARγ antagonists. Hence, according to our results, bioactive peptides resulting from NPC rice consumption might have an antiadipogenic effect via PPARγ interactions, but further experimentation and validation in suitable biological model systems are necessary to gain more insight and to provide evidence to support our in silico findings.

The pulsed electric field (PEF) was applied to improve the extraction yield and properties of rice bran proteins from two rice varieties (“Kum Chao Mor Chor 107” and “Kum Doi Saket”). As compared to the conventional alkaline extraction, PEF treatment at 2.3 kV for 25 min increased the protein extraction efficiency by 20.71–22.8% (p < 0.05). The molecular weight distribution detected by SDS-PAGE and amino acid profiles of extracted rice bran proteins was likely unchanged. The PEF treatment influenced changes in the secondary structures of rice bran proteins, especially from the β-turn to the β-sheet structure. Functional properties of rice bran protein including oil holding capacity and emulsifying properties were significantly improved by PEF treatments by about 20.29–22.64% and 3.3–12.0% (p < 0.05), respectively. Foaming ability and foam stability increased by 1.8- to 2.9-fold. Moreover, the in vitro digestibility of protein was also enhanced, which was consistent with the increment of DPPH and ABTS radical-scavenging activities of peptides generated under in vitro gastrointestinal digestion (37.84–40.45% and 28.46–37.86%, respectively). In conclusion, the PEF process could be a novel technique for assisting the extraction and modification of the protein’s digestibility and functional properties.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on pea and rice protein fermented by Shiitake mushroom (Lentinula edodes) mycelia as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is a mixture of fermented pea and rice protein concentrates (65% and 35%, respectively). The NF is proposed to be used as a food ingredient in specific food categories. The target population is the general population. The major constituent of this NF is protein (≥ 75% dry weight), which is well digestible and provides sufficient amounts of essential amino acids. Although a tolerable upper intake level (UL) has not been derived for protein, the protein intake from the NF may nevertheless further contribute to an already high dietary protein intake in Europe. The Panel notes that the cumulative exposure to the nutrients and contaminants analysed does not raise concern. The reported values for the levels of antinutritional factors in the NF are comparable to those in other foodstuffs. The Panel considers that taking into account the composition of the NF and the proposed conditions of use, consumption of the NF is not nutritionally disadvantageous. No toxicological studies with the NF were provided by the applicant; however, the Panel considers that no toxicological studies are required for this NF. The NF has the potential capacity to sensitise individuals or to induce allergic reactions in individuals allergic to pea, rice and Shiitake mushroom. However, this risk is expected not to be higher than that resulting from the normal consumption of pea, rice or the fruiting body of the Shiitake mushroom. The Panel considers that the NF is safe at the proposed conditions of use. [ABSTRACT FROM AUTHOR]

In this study, the rice protein (RP) fractions (albumin, globulin, glutelin, and prolamin) in rice bran were obtained through the sequential extraction method using 2% (w/w) NaCl, 0.1 N NaOH, and 70% (w/w) ethanol and the proportions of water-soluble protein fractions (albumin) were compared among different degrees of milling (DM; 3%, 5%, 7%). The three types of bran showed different chemical components and populations of the four RP fractions. The 7% DM of brown rice is the stage at which the bran layers are completely removed and white rice is produced. In the 7%-DM bran, the content of water-soluble albumin was the highest. The extracted RP fractions contained eight essential amino acids and among them, albumin had the highest content of lysine. The secondary structures measured by circular dichroism spectroscopy were rich in alpha-helices. These results provide basic data for the extraction and utilization of water-soluble proteins from rice bran. [ABSTRACT FROM AUTHOR]

Abstract Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on pea and rice protein fermented by Shiitake mushroom (Lentinula edodes) mycelia as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is a mixture of fermented pea and rice protein concentrates (65% and 35%, respectively). The NF is proposed to be used as a food ingredient in specific food categories. The target population is the general population. The major constituent of this NF is protein (≥ 75% dry weight), which is well digestible and provides sufficient amounts of essential amino acids. Although a tolerable upper intake level (UL) has not been derived for protein, the protein intake from the NF may nevertheless further contribute to an already high dietary protein intake in Europe. The Panel notes that the cumulative exposure to the nutrients and contaminants analysed does not raise concern. The reported values for the levels of antinutritional factors in the NF are comparable to those in other foodstuffs. The Panel considers that taking into account the composition of the NF and the proposed conditions of use, consumption of the NF is not nutritionally disadvantageous. No toxicological studies with the NF were provided by the applicant; however, the Panel considers that no toxicological studies are required for this NF. The NF has the potential capacity to sensitise individuals or to induce allergic reactions in individuals allergic to pea, rice and Shiitake mushroom. However, this risk is expected not to be higher than that resulting from the normal consumption of pea, rice or the fruiting body of the Shiitake mushroom. The Panel considers that the NF is safe at the proposed conditions of use.

The role of endogenous/exogenous rice protein and its hydrolysates in the enzymatic hydrolysis resistance of rice starch was investigated. Scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and Fourier transform infrared spectroscopy (FTIR) results showed that different types of rice endogenous proteins retarded the digestion of rice starch by the same way. Exogenous addition of protein hydrolysates was more effective than protein for impeding starch digestion. FTIR results indicated that rice protein hydrolysates were bound to starch granules through hydrogen bonds, and their interaction strengthened the ordered structure of the starch. Further, the intensity of the starch V- type peak was enhanced after the addition of protein hydrolysates, indicating that some peptides or free amino acids released by the protein formed complexes with the starch, thereby contributing to high slowly-digestible starch content. These findings provide a theoretical basis for the preparation of low glycemic index starch-based foods. [Display omitted] • Protein hydrolysates were more effective than proteins in impeding starch digestion. • Rice protein and its hydrolysates were bound to starch through hydrogen bonds. • Protein hydrolysates formed complexes with starch. • Rice protein and its hydrolysates strengthened the ordered structure of starch. [ABSTRACT FROM AUTHOR]

Rice protein is a suitable alternative protein source for dairy protein in infant formulas on account of its unique nutrition and hypoallergenicity. Rice protein was isolated through enzymatic hydrolysis (Alcalase, papain, bromelain, Flavourzyme®) in combination with high-pressure processing (HPP) (400 MPa for 15 min at 25 °C) to enhance its functional properties and broaden its food processing applications. The effect of the HPP-treated rice protein hydrolysate on dexamethasone (DEX)-induced atrophy in C2C12 myotubes was also studied. The length of myotubes was observed under a light microscope, and periodic acid Schiff staining. The results showed that even though enzymatic hydrolysis and HPP treatment affected the color of the resulting rice protein, the protein content (3120.31 ± 42.15), branched chain amino acid (BCAA) content (15.12 ± 1.03), peptide content (31.25 ± 0.55), and amino acid composition of the rice protein were significantly increased. Moreover, the combined enzymatic and HPP treatment effectively overcame the problem of limited solubility and water-holding capacity. Rice protein produced through enzymatic and HPP treatment exhibited a higher free radical scavenging activity and oxygen radical absorbance capacity. It also alleviated DEX-induced muscle atrophy in C2C12 myotubes as indicated by the increase in myotube length. In short, the enzymatic and HPP treatment of rice protein not only overcame limitations, but also produced rice protein with high functionality in terms of antioxidant and therapeutic effects on muscle atrophy. The rice protein hydrolysate produced through enzymatic hydrolysis and HPP treatment showed the potential for use as an ingredient for functional foods in the nutraceutical industry.

The proteins that are subjected to hydrolysis processes increase their bioactive and functional properties, for this reason, in this work the protein hydrolysis was monitored by means of spectroscopy, to determine the structural changes that proteins undergo during hydrolysis. Enzymatic hydrolysis with endo / exoproteases was carried out on the three protein isolates, the enzymes used were Alcalase 2.4L and Flavorzyme® from the Sigma laboratory. The enzyme / substrate ratio was 5%; degrees of hydrolysis between 46% and 38.4% were obtained for Quinoa protein isolate and Rice protein isolate, respectively. Both follow-up of Quinoa protein isolate and Soy protein isolate enzymatic hydrolysis was 60 minutes with Alcalasa®2.5L and 120 minutes with Flavorzima®, with respect to Rice protein isolate, the established hydrolysis times were 60 minutes with Alcalase 2.4L and 20 minutes with Flavorzima®; Times longer than these, no significant differences were observed in the degree of hydrolysis. By way of comparison, the protein isolates and their hydrolysates were studied in the mid-infrared range (4000 cm-1 to 600 cm-1) to obtain information on the structure of the protein, for this, a technique was used deconvolution of the spectrum by means of the Fourier transform function. These spectra showed significant differences in the secondary structure of the protein, regarding the analysis of the areas, which were determined using a Gaussian function; the most favorable changes were mainly in the formation of b-sheet and b-turns structures.

Rice protein (RP) and polyphenols are often used in functional foods. This study investigated the non-covalent interactions between RP and three polyphenols (curcumin, CUR; quercetin, QUE; resveratrol, RES) and used the complexes as emulsifiers to create emulsions. Three polyphenols interacted with RP to varying extents, with QUE showing the greatest binding affinity and inducing the greatest alterations in its secondary structure. Molecular docking analysis elucidated the driving forces between them including hydrophobic interactions, hydrogen bonding, and van der Waals forces. Combination with QUE or RES induced structural changes of RP, increasing particle size of complexes. The synergistic effect of polyphenols and protein also enhanced radical scavenging capacity of complexes. Compared to pure protein, all complexes successfully created emulsions with smaller particle size (378-395 nm vs. 470 nm), higher absolute potential (37.43-38.26 mV vs. 35.62 mV), and greater lipid oxidation stability by altering protein conformation., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)

This study investigated the effects of pH treatment, heat treatment, pH‐synergistic heat treatment and glycosylation on the functional properties of rice protein (RP). The results showed that all treatment methods could improve the functional properties of RP. Heat treatment improved functional properties by generating aggregates after RP unfolds, and pH treatment improved those by causing RP to hydrolyse and aggregate. Compared to RP, the solubility, emulsification activity (EA), emulsification stability (ES), foaming activity (FA), surface hydrophobicity and in vitro digestibility of pH‐synergistic heat treatment of RP (S‐RP) were increased by 11.47, 3.12, 3.45, 2.27, 3.36 and 2.12 times, respectively. Glycosylation mainly improved the functional properties of RP by introducing hydrophilic groups. Compared to those of S‐RP, solubility, EA, ES, FA, surface hydrophobicity and in vitro digestibility of RP–dextran conjugates (RPDCs) were increased by 2.03, 1.25, 1.97, 1.05, 1.64 and 1.48 times, respectively. Therefore, compared to glycosylated chemical modification, heat treatment and pH treatment had a weak improvement in the functional properties of RP. The comparison of pH‐treated RP (pH‐RP) and RP–dextran mixtures (RPDMs) showed that in the absence of heat treatment, carbonyl ammonia condensation almost did not occur. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine the effect of rice and hemp protein addition together with transglutaminase on the quality and fat content of fried instant noodles. The following parameters have been analyzed during this research: the amount of water, fat content, hydration time, color and texture parameters. The evaluation of sensory parameters before and after cooking of instant noodles has been performed. It can be concluded that the addition of TGase significantly decreased the fat content; the recipe with a 3% hemp protein addition with TGase in an amount of 2% was the most promising solution to obtain a low-fat product. On the other hand, the better consumer acceptance levels were observed for the rice protein addition (1%) with 2% TGase. It seems that the most promising product is the sample with a 5% addition of rice protein with 2% TGase-a reduction in the fat content by 30% (from 25% to 16%). The addition of rice protein, hemp protein and TGase reduced the fat content of the instant noodles in comparison to the control sample. The additives used had an impact on the L*, a* and b* color parameters. All instant noodles obtained during the research process were characterized by a short hydration time, which did not exceed 5 min. During the sensory evaluation, analyzed samples of the instant noodles obtained scores higher than 4.2 points on a five-point scale. [ABSTRACT FROM AUTHOR]

The study examined the potential nutritive value of rice protein (RP) through Maillard reaction. Structures and properties of synthetic conjugates of RP and exopolysaccharide (EPS) from Arthrobacter ps‐5 were investigated systematically. Fluorescence characteristics and high molecular weight compounds appeared in Maillard reaction products (MRPs). Moreover, EPS or its degradation products in the form of covalent bond cross‐linked with RP were identified, where –NH2 disappeared and C=O, C=N and C–N increased. Determination of free –SH residues suggested mutual conversion between disulfide bonds and sulfhydryl groups occurred during Maillard reaction. HPLC analysis identified conjugates with different molecular weight, where melanoprotein was formed by covalent bonds. As RP conjugated with EPS, the molecules spread out and changed the spatial structure. Functional properties of MRPs, including solubility, foaming activity, emulsifying ability and resistance to oxidation, were greatly improved. The study has discovered an efficient method for increasing the application value of plant protein. [ABSTRACT FROM AUTHOR]

Hybrid meat products are an excellent strategy to incorporate plant proteins into traditional meat formulations considering recent market trends focusing on the partial reduction in red meat content. In this work, we evaluated the effects of different concentrated plant proteins (soy, pea, fava bean, rice, and sunflower) in partially replacing meat in meat emulsion model systems. Soy, pea, and sunflower proteins showed great compatibility with the meat matrix, giving excellent emulsion stability and a cohesive protein network with good fat distribution. Otherwise, adding rice and fava bean proteins resulted in poor emulsion stability. Color parameters were affected by the intrinsic color of plant proteins and due to the reduction in myoglobin content. Both viscoelastic moduli, G′ and G″ decreased with the incorporation of plant proteins, especially for rice and fava bean. The temperature sweep showed that myosin denaturation was the dominant effect on the G′ increase. The water mobility was affected by plant proteins and the proportion between immobilized and intermyofibrillar water was quite different among treatments, especially those with fava bean and rice proteins. In vitro protein digestibility was lower for hybrid meat emulsion elaborated with rice protein. It is concluded that soy, pea, and mainly sunflower proteins have suitable compatibility with the meat matrix in emulsified products.

Coatings based on plant by-products can contribute to the enhancement of raw material by preparing value-added products. In addition, the extension of shelf-life of eggs contributes to the reduction of food losses and decreases the use of refrigeration, energy demand, production costs, and consequently avoid the increase in the price of the final product. The rice protein concentrate (RPC) and plus Brazilian green propolis (GP), were used in the manufacture of coatings used to extend the shelf-life of eggs during storage for 6 ​wk at 20 ​°C. In this regard, some quality parameters of eggs were analyzed in this research. The coatings based on RPC and GP delayed the loss of internal egg quality, since avoided moisture loss through the pores of the eggshell. The weight loss increased (P ​

Rice protein has attracted considerable attention recently due to its physiological effects. This study extracted the proteins from paddy rice (PR) and germinated paddy rice (GPR) using three methods i.e., alkaline, sodium dodecyl sulfate (SDS) reagent and enzymatic extractions. The extracted proteins or protein fractions were assessed for their properties using various techniques. Data were analyzed by 2′3 factorial design experiment. It was found that germination and extraction methods significantly affected the concentration of protein fractions when analyzed by Bradford assay. Average protein fraction concentration of the GPR was lower than that of PR. SDS-PAGE patterns of protein fractions obtained from PR and GPR using any extraction method displayed similar protein profiles. Three major protein bands at about 13 kDa (prolamin), 22–23 kDa (basic glutelin) and 37–39 kDa (acidic glutelin) with small amount of 57 kDa proglutelin were observed. For amino acid profile, germination increased the content of most amino acids, resulting in the higher content of amino acids in GPR, excepted for some amino acids. When processed with in vitro digestion, protein fractions from GPR exhibited a higher level of digestibility than those from PR as evidenced by the less intensity of the protein bands obtained from SDS-PAGE. Alkaline and SDS reagent extractions provided more digestible protein fractions than enzymatic extraction. Extraction methods also influenced phase transition of protein fractions as investigated by a DSC. Alkaline extraction resulted in protein fractions with higher phase transition temperature than the other methods. For antioxidant capacity, extraction methods as well as germination significantly affected antioxidant capacity of the protein fractions. Enzymatic extraction provided protein fractions with the best antioxidant capacity.

[Display omitted] • Proteolysis reduced the fibril formation ability of rice protein. • Proteolysis pretreatment improved the foaming properties of rice protein fibrils. • The addition of rice protein hydrolysate fibrils improved the quality of cake. Proteolysis prior to fibrillation can change the functional properties of protein fibrils. This study aimed to investigate the effects of proteolysis pretreatment by alkaline protease on formation, structure, and foaming properties of rice protein fibrils. Thioflavin T fluorescence and conversion assays showed that proteolysis reduced the fibril formation capacity of rice protein. After 12 h of heating, the percent conversion of rice protein and rice protein hydrolysates to fibrils reached 60.32 ± 1.07% and 30.43 ± 2.01%, respectively. Transmission electron microscopy images showed that fibrils derived from rice protein hydrolysates had a longer contour length than rice protein fibrils. The foaming capacity and stability of rice protein hydrolysate fibrils increased by 16.70% and 11.27%, respectively, compared with those of rice protein fibrils. The addition of rice protein hydrolysate fibrils improved the texture of cakes. These results suggested that rice protein hydrolysate fibrils could be a promising plant-based foaming agent. [ABSTRACT FROM AUTHOR]

The effects of the endogenous protein on the rheology and digestibility of rice starch were investigated. The protein augments the apparent morphology of the protein-starch mixture from smooth and dense to a uniform porous structure and finally a flaky and loose structure. Low protein content will assist the dispersibility of the starch granule, increasing the storage modulus (G′) of the protein-starch mixture. However, the elevated protein content will subsequently reduce the storage modulus of the mixture. In contrast, the loss modulus (G″) did not significantly change with different protein contents. From in vitro starch digestion analysis, when the amount of protein was varied, there was no significant difference in the slowly digestible starch. The level of rapidly digestible starch, however, increased at low protein content but subsequently decreased at the higher protein level. At the other end of the spectrum, resistant starch gradually increased with the increase in protein content. [Display omitted] • Effect of endogenous proteins on the rheology and digestion of rice starch. • Protein causes the infrared peak of the mixture to decrease and forms v-shaped crystals. • The addition of protein inhibits the gelatinization of starch. • The addition of protein reduces the action of enzymes resulting in reduced digestibility. [ABSTRACT FROM AUTHOR]

Soft composite gels were prepared with ultrasound-treated rice protein (URP, 4%) and rice starch (RS, 6%). The compositional and physical attributes of URP were elucidated, and the textural, rheological and structural properties of the composite gels were characterized. URP showed a reduced particle size, improved solubility, and increased heat tolerance. Cooked (65 °C for 20 min, then heated to 95 °C at 1 °C/min) RS + URP gels displayed a homogeneous and smooth texture with a range of reduced hardness (62%–78.3%) compared with RS gel while largely retaining the water-holding capacity. The viscosity and shear moduli (Gʹ and G′′) of the gels decreased correspondingly, and starch retrogradation was partially inhibited by the interaction with URP. A salient amorphous state revealed by X-ray diffraction confirmed weaker amylose association, in corroboration with non-covalent interactions between RS and URP shown by FTIR spectroscopy. These findings suggest that URP can be a functional ingredient for the development of soft, protein-rich, starch-based gel products suitable for the dysphagia diet. [Display omitted] • Ultrasound-treated rice protein (URP) has smaller particle size and higher solubility. • URP–rice starch composite gels display homogeneous and smooth texture. • URP inhibits starch retrogradation in composite gels. • URP reduces the hardness yet retains water-holding capacity of composite gels. • Hydrogen bond is a significance force in rice starch–URP soft gels. [ABSTRACT FROM AUTHOR]

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.

Modification of plant-based protein for promoting wide applications is of interest to the food industry. Rice protein from rice residues was modified by homogenization, and its effect on pasting properties (including gelatinization and rheology) of rice starch was investigated. The results showed that homogenization could significantly decrease the particle size of rice protein and increase their water holding capacity without changing their band distribution in SDS-PAGE. With the addition of protein/homogenized proteins into rice starch decreased peak viscosity of paste. The homogenized proteins decreased breakdown and setback value when compared with that of original protein, indicating homogenized protein might have potential applications for increasing the stability and inhibiting short-term retrogradation of starch paste. The addition of protein/homogenized proteins resulted in a reduction in the viscoelasticity behavior of starch paste. These results indicate that homogenization would create a solution to alter the physicochemical properties of plant proteins, and the homogenized proteins may be a potential candidate for development of protein-rich starchy products.

The effects of heat treatment on protein interaction, surface hydrophobicity, protein profile, amino acid composition, and in vitro digestibility of individual rice protein fractions were investigated. Heat treatment at 100 °C for 20 min had no negative effect on essential amino acids in rice protein. Surface hydrophobicity increased significantly with the increased heat treatment temperature. Moreover, free-thiol content decreased significantly with increased temperature and time extension. Hydrophobic interactions contributed to the heat-induced interaction of glutelin and prolamin. Intramolecular disulfide linkages participated in the heat-induced interaction of all rice-protein fractions. Heat treatment had no effects on the in vitro digestibility of glutelin, globulin, and albumin. Thus, the heat-induced interactions of glutelin, globulin, and albumin were not related to their digestibility. By contrast, the formation of intramolecular disulfide bonds and hydrophobic interactions in prolamin may reduce its digestibility by strengthening protein bodies-Is. [ABSTRACT FROM AUTHOR]

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Carbohydrate-digested rice (CDR) residue, the production waste of electrolyte drinks, contains high levels of proteins (approximately 50% of dry matter). Methods for effectively extracting protein from CDR were investigated in this study by comparing alkaline and enzymatic extraction. Alkaline extraction was performed using different concentrations of sodium hydroxide (NaOH). Enzymatic extraction was performed with either commercial Alcalase® or Flavourzyme®. Protein recovery and solubility, and total soluble protein obtained via each method were compared to determine extraction effectiveness. In addition, extraction factors affecting protein recovery were adjusted to determine the optimal conditions for each method. Alcalase provided the maximum protein recovery (30.04%), while less protein recovery was achieved with 0.1 N NaOH (55 °C), 1 N NaOH (55 °C), and Flavourzyme. Although the protein recovery achieved by 0.1 N NaOH (27.43%) was close to that of the Alcalase method, protein solubility by extraction with 0.1 N NaOH was much lower (23.46%) than that achieved via the enzymatic method (100%). Hence, the total soluble protein resulting from Alcalase extraction was higher than that obtained using either of the alkaline methods. Consequently, Alcalase extraction was determined to be the most effective method for extracting protein from CDR.

The mechanism of the suppressive effect of rice albumin (RA) on postprandial hyperglycemia after glucose loading was investigated. In order to examine if small peptides derived from RA are responsible for prevention of postprandial hyperglycemia, RA was hydrolysed to indigestible high-molecular-weight peptides (HMP) and low-molecular-weight peptides (LMP) by trypsin, HMP and LMP being fractionated by gel-filtration chromatography. In oral glucose tolerance test (OGTT), both HMP and LMP suppressed the increase in blood glucose levels. In vitro diffusion test results showed that HMP adsorbed glucose and retarded its diffusion rate like dietary fibers. On the other hand, LMP suppressed the expression of sodium-dependent glucose transporter-1 (SGLT1) in STC-1 cells. Therefore, the suppressive effect of RA on postprandial hyperglycemia would be due to the dual actions of HMP and LMP. Our results demonstrated the potential use of RA as a functional food material to prevent diabetes.

Dispersion of rice protein (RP) at a neutral pH is highly important for its application in the food industry. We analyzed the solubility of RP at different pH conditions and found higher solubility at pH < 3 and pH > 8 than at a neutral pH. Furthermore, at pH 2, the RP solubility improved from 30 to 63% with sonication; however, the samples precipitated when the pH was increased from 2 to 7. To circumvent this, anionic pectin and sodium alginate were added to the RP solution at pH 2. Pectin formed a complex with RP at pH 2, showing a shift in the zeta-potential from 17.3 mV (RP only) to − 1.0 mV (RP plus 1% pectin). Interestingly, the formation of this RP-pectin complex allowed RP to remain dispersed when the pH was increased to 7. Moreover, a stable emulsion could be prepared using the RP-pectin complex as an emulsifier. [ABSTRACT FROM AUTHOR]

The major aim of this study was to investigate the effect of rice protein (RP) on the activation of endogenous antioxidant defense in growing and adult rats. After 2 weeks, RP activated nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) by suppressing Kelch-like ECH-associated protein 1 (Keap1) and Cullin 3 (Cul3) in growing and adult rats. Compared with casein, the upregulation of antioxidant responsive element (ARE)-driven antioxidant expression levels (glutamate cysteine ligase catalytic subunit, glutamate cysteine ligase modulatory subunit, glutathione synthase, glutathione reductase, glutathione S-transferase, glutathione peroxidase, catalase, superoxide dismutase, heme oxygenase 1, NAD(P)H:quinone oxidoreductase 1) were found in RP groups. Also, RP upregulated methionine sulfoxide reductase (MsrA, MsrB2, and MsrB3) expression levels in growing and adult rats. As a result, RP enhanced endogenous antioxidative capacities to reduce hepatic accumulations of malondialdehyde, protein carbonyl, and reactive oxygen species. This study demonstrates that RP exerts the endogenous antioxidant capacity in growing and adult rats, which is due to stimulating Msr antioxidant expression and activating Nrf2-ARE pathway. Results suggest that the antioxidant activity induced by RP is independent of age. [ABSTRACT FROM AUTHOR]

Methionine sulfoxide reductase (Msr) and glutathione (GSH) are two endogenous antioxidant systems for depressing oxidative stress. The aim of this study is to investigate the role of methionine in involving the stimulation of endogenous antioxidant capacity of rice protein (RP). Seven‐week‐old male Wistar rats (body weight 180–200 g) were fed with commercial pellets (as control), methionine, and RP for 2 weeks. Compared with control, GSH synthesis and expressions of MsrA, MsrB2, and MsrB3 were stimulated by methionine and RP. After 2 weeks of feeding, Nrf2 was activated by RP and methionine, whereas the expressions of Keap1 and Cul3 were depressed. The ARE‐driven antioxidant expressions (GCLC, GCLM, GS, HO‐1, NQO1, CAT, SOD, GR, GST, GPx) were upregulated by methionine and RP. Results suggest that the endogenous antioxidant response induced by RP is primarily attributed to the methionine availability, in which the stimulation of Msr and GSH antioxidant system via Nrf2‐ARE pathway. Practical applications: Rice protein is a major plant protein, which is rich in sulfur‐containing amino acids and widely consumed in the world. This paper emphasizes that the amino acid plays a key role in inducing the antioxidant activity of rice protein. The present study provides an insight that the methionine availability of rice protein will be a useful target for health promoting by activating endogenous antioxidant response against ROS‐induced oxidative damage. [ABSTRACT FROM AUTHOR]

To elucidate the influence of methionine on the endogenous antioxidant activity of rice protein (RP), growing and adult rats were fed with RP and methionine-supplemented RP (RM). After 2 weeks feeding, hepatic contents of ROS were significantly reduced by RP and RM. The endogenous antioxidant responses were induced by RP and increased by RM, in which methionine sulfoxide reductases (MsrA, MsrB2, MsrB3) expression and glutathione synthesis were uniformly stimulated and up-regulated with increasing consumption of methionine. With the intake of RP and RM, Nrf2 was activated through depressing Keap1 and Cul3, resulting in the up-regulation of antioxidant-responsive element (ARE)-driven antioxidant expressions (GCLC, GCLM, CAT, SOD, HO-1, NQO1) with increasing dietary level of methionine. The present study demonstrates that methionine can augment the endogenous antioxidant activity of rice protein, which is primarily attributed to stimulating methionine sulfoxide reductases expression and enhancing glutathione synthesis via Nrf2-ARE pathway. Results suggest that the methionine availability might play a key role in inducing and augmenting the endogenous antioxidant response exerted by rice protein, which is independent of age. [ABSTRACT FROM AUTHOR]

Summary: Malondialdehyde (MDA) was selected to represent a secondary by‐product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non‐disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration. [ABSTRACT FROM AUTHOR]

The purpose of this study was to optimize the rice protein extracted using a response surface methodology. The experiment was designed based on a CCD (Central Composite Design), and the independent variables were the high pressure (X1, 0-400 MPa) and processing time (X2, 0-10 minutes). The results of the extraction content (Y1), residue content (Y2), and recovery yield (Y3) were fitted to a response surface methodology model (R2= 0.92, 0.92, and 0.93, respectively). Increasing the pressure and processing time has a positive effect on the extraction content (Y1), residue content (Y2), and recovery yield (Y3). Therefore, these high-pressure conditions (independent variables) can significantly affect the improvement in rice protein extraction efficiency. Thus, the optimal conditions of X1 and X2 were 400 MPa and 10 min., respectively. Under these optimal conditions, the predicted values of Y1, Y2, and Y3 were 62.93, 57.53 mg/g, and 91.76%, respectively. [ABSTRACT FROM AUTHOR]

• Rice protein (RP) fibrils were disrupted by Cu2+ and Fe3+ to fragments. • Cu2+ and Fe3+ added before heating resulted in rapid amorphous aggregation of RP. • Ca2+ facilitated RP fibril formation, which was related to the Ca2+addition time. The effects of Ca2+, Cu2+, and Fe3+ on rice protein (RP) fibril formation were investigated in this study. Low Ca2+ concentration (≤150 mM) moderately unfolded the conformation of RP, promoting the exposure of hydrophobic sites and RP fibril assembly. Fibril formation was especially promoted with earlier addition of Ca2+. Cu2+ and Fe3+ inhibited RP fibril formation in a dose-dependent manner, and the inhibitory effect of Fe3+ was stronger due to higher affinity with RP. Additionally, the addition of Cu2+ and Fe3+ reduced α-helix and β-sheet contents of RP, respectively, hindering the formation of stacked β-sheet, the main internal structure of fibrils. These two ions also resulted in the formation of random aggregates within 15–50 nm, which further inhibited the conversion of proteins to fibrils. Moreover, Cu2+ and Fe3+ prevented the recruitment of nucleus into fibril-growth-sites, and formed fibrils were disrupted into fragments when these ions were added. [ABSTRACT FROM AUTHOR]

The FOs-RPH conjugates were prepared under the catalyst of laccase and ascorbic acid/hydrogen peroxide, and the conjugates had higher solubility and antioxidant activity but lower emulsifying property than RPH. [Display omitted] • The FOs-RPH conjugate was prepared by laccase or ascorbic acid/hydrogen peroxide. • Two conjugation methods induced different conjugation sites and efficiencies. • Conjugation with FOs improved the solubility and antioxidant activity of RPH. • Conjugation with FOs decreased the emulsifying activity and stability of RPH. Rice protein hydrolysate (RPH) and feruloyl oligosaccharides (FOs) were conjugated under the catalysis of laccase and free radical, and the structure and properties of the resultant conjugates were studied. Electrophoresis analysis demonstrated that conjugation with FOs increased the molecular weight of some fractions in RPH, which confirmed the formation of both conjugates. The conjugation degree of laccase-induced conjugate and radical-induced conjugate was 60.45% and 22.70%, respectively. Laccase-catalyzed conjugation decreased the tyrosine residue content of RPH but had no significant effect on the free amino group content, which suggested that tyrosine residues were the conjugation site in the laccase-induced conjugate. However, radical-catalyzed conjugation decreased both the free amino group content and the tyrosine residue content, which indicated that both free amino groups and tyrosine residues were the conjugation site in the radical-induced conjugate. The ultraviolet, fluorescence and circular dichroism spectroscopy analysis revealed that conjugation with FOs significantly altered the secondary and tertiary structure of RPH. In addition, conjugation with FOs increased the solubility and antioxidant activity of RPH but decreased the emulsifying activity and stability. Particularly, the radical-induced conjugate had greater anti-aggregation capacity and antioxidant activity but lower emulsifying activity and stability than the laccase-induced conjugate, which might be due to that their conjugation site and degree were different. [ABSTRACT FROM AUTHOR]

The effects of different ratios of pea protein (PP) on the gel characteristics of rice protein (RP) and the formation mechanism of RP-PP binary mixed protein were investigated. The formation of the basic viscoelastic network by PP may aid in the gelatinization of RP. Results showed that the RP/PP (1:0.5) mixed protein had the highest gel strength and hardness (P < 0.05), and scanning electron microscopy (SEM) findings revealed that PP incorporation of the protein gel established a homogeneous and denser gel network structure. Furthermore, as the proportion of PP increased, the relaxation time of T 2b , T 21 , T 22 and surface hydrophobicity decreased, indicating that the hydrophobic interactions of binary proteins restricted water mobility. Results revealed that different behaviors of gels may be attributed to the secondary structure content of proteins. The formation mechanism of binary mixed protein gel was the interpenetration of independently-formed protein network by RP and PP, respectively. It was due to the hydrophobic interactions and hydrogen bonding between RP and PP enhancing the interactions and gel strength of mixed protein. In summary, results confirmed that PP could be used as a potential ingredient for improving the characteristics of RP/PP binary mixed protein gels. [Display omitted] • A structural binary mixed protein gel was formed by combining rice and pea proteins. • Synergism of RP/PP 1:0.5 resulted in higher gel strength and hardness. • Hydrophobic interactions and hydrogen bonding drove the formation of mixed gels. • Synergistic effect of RP/PP forms structural gel by independent protein network. [ABSTRACT FROM AUTHOR]

The goal of this study was to determine the effect of rice and hemp protein addition together with transglutaminase on the quality and fat content of fried instant noodles. The following parameters have been analyzed during this research: the amount of water, fat content, hydration time, color and texture parameters. The evaluation of sensory parameters before and after cooking of instant noodles has been performed. It can be concluded that the addition of TGase significantly decreased the fat content; the recipe with a 3% hemp protein addition with TGase in an amount of 2% was the most promising solution to obtain a low-fat product. On the other hand, the better consumer acceptance levels were observed for the rice protein addition (1%) with 2% TGase. It seems that the most promising product is the sample with a 5% addition of rice protein with 2% TGase-a reduction in the fat content by 30% (from 25% to 16%). The addition of rice protein, hemp protein and TGase reduced the fat content of the instant noodles in comparison to the control sample. The additives used had an impact on the L*, a* and b* color parameters. All instant noodles obtained during the research process were characterized by a short hydration time, which did not exceed 5 min. During the sensory evaluation, analyzed samples of the instant noodles obtained scores higher than 4.2 points on a five-point scale.

Blended meat/plant products are capturing industry market space at the retail counter for value-added beef products. Plant protein ingredients can be added to meat formulations to create appealing and functional products. Ground beef was combined with one of three plant protein inclusion treatments: control, pea, oat, or rice, along with 5% textured vegetable protein (TVP) and 1.5% soy protein concentrate then formed into 226 g patties containing up to 10% plant-based proteins. Patties were analyzed for fresh and cooked characteristics throughout a 5- or 7-day retail display. The inclusion of plant-based proteins negatively affected the instrumental tenderness values which were greater (p < 0.01) in plant-inclusion patties compared to the control patties. The inclusion of plant proteins increased (p = 0.01) the cooking yield of patties compared to the control. Cooking time was longer (p = 0.04) for oat patties compared to the control patties. Cooked color values for vegetable inclusion patties did not affect (p = 0.12) lightness (CIE L*) values; however, redness (CIE a*) was greater (p < 0.01) for rice than all other treatments and yellowness (CIE b*) values were greater (p < 0.01) for all protein treatments compared to the control. Rice improved (p < 0.01) fresh a* values on day 5 of display compared to the control; whereas pea decreased (p = 0.04) values compared to the control. There was a treatment × day interaction (p < 0.01) on lipid oxidation values with a reduction in values on day 3 for all vegetable proteins compared to the control and on day 7 lipid oxidation was reduced (p ≤ 0.03) for oat patties.

Plant-based protein sources have a characteristic aroma that limits their usage in various meat-alternative formulations. Despite being the most popular plant-based protein, the allergenicity of soy protein severely restricts the potential adoption of soy protein as an animal substitute. Thereby, allergen-free plant-protein sources need to be characterized. Herein, we demonstrate a rapid solid-phase-microextraction gas-chromatography/mass-spectrometry (SPME-GC/MS) technique for comparing the volatile aroma profile concentration of two different allergen-free plant-protein sources (brown rice and pea) and comparing them with soy protein. The extraction procedure consisted of making a 1:7 w/v aqueous plant protein slurry, and then absorbing the volatile compounds on an SPME fibre under agitation for 10 min at 40 °C, which was subsequently injected onto a GC column coupled to an MS system. Observed volatile concentrations were used in conjunction with odour threshold values to generate a Total Volatile Aroma Score for each protein sample. A total of 76 volatile compounds were identified. Aldehydes and furans were determined to be the most dominant volatiles present in the plant proteins. Both brown rice protein and pea protein contained 64% aldehydes and 18% furans, with minor contents of alcohols, ketones and other compounds. On the other hand, soy protein consisted of fewer aldehydes (46%), but a more significant proportion of furans (42%). However, in terms of total concentration, brown rice protein contained the highest intensity and number of volatile compounds. Based on the calculated odour activity values of the detected compounds, our study concludes that pea proteins could be used as a suitable alternative to soy proteins in applications for allergen-free vegan protein products without interfering with the taste or flavour of the product.