Search

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]

Summary: Dextran was grafted on to rice protein (RP) by the wet‐heating Maillard reaction, and the structure and functional properties of the rice protein–dextran conjugates (RPDCs) were investigated. The RPDCs obtained by the Maillard reaction exhibited superior functionality compared with original RP. The solubility, emulsifying activity index, emulsifying stability index, foaming activity index and foaming stability of the RPDCs increased by factors of 7.50, 1.79, 2.20, 1.69 and 2.01, respectively, compared to original RP. The molecular weight, particle size distribution, surface hydrophobicity, secondary structures, amino acid compositions and chemical bonds of RPDCs were also characterised. The structure–function relationship was preliminary discussed, and the relationship suggests that the improvements in the functional properties were closely related to structural changes. [ABSTRACT FROM AUTHOR]

In this study, rice husk biochar was engineered with abundant iron ion sites to enhance the enrichment of antioxidant peptides from rice protein hydrolysates through metal-chelating interactions. The π-π interactions and metal ion chelation were identified as the primary mechanisms for the enrichment process. Through peptide sequencing, four peptides were identified: LKFL (P1: Leu-Lys-Phe-Leu), QLLF (P2: Gln-Leu-Leu-Phe), WLAYG (P3: Trp-Leu-Ala-Tyr-Gly), and HFCGG (P4: His-Phe-Cys-Gly-Gly). The vitro analysis and molecular docking revealed that peptides P1-P4 possessed remarkable scavenging ability against radicals and Fe2+ chelating ability. Notably, peptide P4 showed radical scavenging activity comparable to glutathione (GSH) against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-3-ethylbenzthiazoline-6-sulphonate (ABTS) radicals. Cellular experiments further confirmed that peptide P4 effectively protected HepG2 cells from oxidative stress-induced damage. The modified rice husk biochar proved to be an effective means for enriching rice antioxidant peptides from protein hydrolysates. [Display omitted] • A functionlized rice husk biochar was prepared for enriching antioxidant peptides. • One-step-enrichment significantly improved the free radical scavenging abilities. • Four antioxidant peptides (LKFL, QLLF, WLAYG, and HFCGG) were identified. • HFCGG showing comparable antioxidant ability to GSH. [ABSTRACT FROM AUTHOR]

The study aims at improving the solubility of rice protein (RP) by covalent coupling of proteins to polysaccharide via Maillard reaction in macromolecular crowding conditions. The formation of RP-dextran conjugates (RPC) was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, size exclusion chromatography and infrared spectra. The optimum conditions for the Maillard reaction between rice protein and dextran were 90 °C, pH 11, 60 min, and the mass ratio of RP to dextran was 1:3. The solubility of the RP-dextran conjugates in the buffer solution of pH 7–9 was greater than 80%. The high solubility of the RP-dextran conjugate was due to the introduction of dextran. Dextran covalently bound to RP has many hydrophilic hydroxyl groups, which reduced the ratio of hydrophobic groups on the surface of RP. At the same time, the emulsification and foaming properties of the RP-dextran conjugates were greatly improved compared to that of original RP. The application of crowded conditions can be used as a new way to enhance the reaction, improve the solubility of rice protein, while retaining the protein structure, thus contributing to the industrialized application of rice proteins. [Display omitted] • Macromolecular crowding environment enhances Maillard reaction of rice protein and dextran. • The yield of the rice protein–dextran conjugate was high to 31.7%. • Glycosylated rice proteins show good solubility, emulsification and foaming properties. [ABSTRACT FROM AUTHOR]

• Screening rice-derived immunopeptide combining peptidomic and in silico strategies. • Four immunopeptides are obtained based on in-silico and in-vitro analyses. • In silico strategy can be used in quickly screening food-derived immunopeptides. The new food-derived bio-functional peptides are urgently needed globally, but the separation and purification process for obtaining the immunopeptides from food is low efficiency and highly time-consuming. In the present study, rice proteins were extracted and identified by using liquid chromatography/tandem mass spectrometry (LC-MS/MS). Furthermore, a strategy combining immuno-prediction and in silico simulation was used to screen for peptides showing immunomodulatory activity, including inhibition of the release of nitric oxide, tumor necrosis factor-α, and the interleukins IL-6 and IL-1β in lipopolysaccharide-induced RAW264.7 mouse macrophages. This LC–MS/MS identification and immuno-prediction method may provide insights for the potential identification of more food-derived immunopeptides. [ABSTRACT FROM AUTHOR]

The effects of microwave treatment Maillard reaction on rice protein (RP) and dextran was investigated. Microwaving accelerated the Maillard reaction between RP and dextran. A solubility of 24.22% was reached by conventional heating for 5 min, whereas microwave treatment obtained a solubility of 64.25% over the same amount of time. The activation energy of the Maillard reaction by microwave treatment was calculated to be 28.52 kJ/mol which is lower than that by conventional heating. Molecular weight analysis and Fourier transform infrared spectroscopy (FTIR) demonstrated that the Maillard reaction induced changes in molecular weight and chemical structure. Spectral analysis showed that the Maillard reaction by microwaving allowed the RP tertiary structure to expand more widely, resulting in better solubility of conjugates. In general, microwave treatment Maillard reaction products (PM) showed higher improvement in functional properties than that of conventional heating Maillard reaction products (PC), this proved that microwave is more capable of improving functional properties. This research demonstrates an efficient method for the processing of RP to improve its functional properties, which can expand its application in the food, cosmetic, and pharmaceutical fields. Image 1 • Microwave promotes Maillard reaction of rice protein and dextran. • Microwave reduces the activation energy of the reaction. • Conjugates prepared by microwave had higher solubility, emulsification and foaming properties. [ABSTRACT FROM AUTHOR]