Functional properties and structural changes of rice proteins with anthocyanins complexation

Multispectral analysis and molecular simulation of quinoa protein-tannic acid interactions: Conformational changes and functional properties

This study used multispectral analysis and molecular simulation to investigate the mechanisms of non-covalent interactions between quinoa protein isolate (QPI) and tannic acid (TA), and its effects on protein conformation. The formation of the QPI-TA complex was confirmed by increased turbidity, polyphenol binding capacity, and UV-visible absorbance. The addition of TA decreased α-helices while increasing β-sheets and random coils, resulting in a looser, more disordered protein structure of QPI. Thermodynamic analysis and molecular docking results indicated that the predominant interactions between QPI and TA are hydrophobic interactions and hydrogen bonds. Molecular dynamics simulations confirmed that the binding sites of TA and QPI were tightly associated, thereby maintaining conformational stability. Additionally, the non-covalent modification by TA significantly enhanced the emulsifying and foaming capacities of QPI. This study provides a theoretical foundation for the application of QPI-polyphenol complexes in the production of emulsified foods.

Non-covalent interaction of rice protein and polyphenols: The effects on their emulsions

In this study, we investigated the non-covalent interaction mechanism between rice protein (RP) and three polyphenols with different concentrations (ferulic acid FA, gallic acid GA, and tannic acid TA) and their effects on the structure and emulsion stability of the proteins. Hydrophobic forces dominated the binding of RP to the polyphenols, and the reaction was heat-absorbing. The three polyphenols are bound to RP in the form of static quenching to form a non-covalent complex, and during the binding process, the RP provides one binding site. RP-polyphenol complexes, particularly RP-GA, enhanced ABTS scavenging and FRAP reduction. Polyphenols improved RP emulsion oxidative stability, inhibiting lipid oxidation and enhancing emulsion rheology and interfacial structure. RP-GA was most effective, maintaining low POV. These findings support the potential applications of RP-polyphenol noncovalent complexes in food processing.

A comprehensive review of the impact of anthocyanins from purple/black Rice on starch and protein digestibility, gut microbiota modulation, and their applications in food products

This review explores the impact of anthocyanins derived from purple and black rice on starch and protein digestibility, gut microbiota modulation, and their applications in food production. Anthocyanins are shown to reduce starch digestibility by forming complexes with starch, thereby inhibiting key digestive enzymes. Additionally, they can influence protein digestion by inducing structural changes that enhance resistance to digestive processes. Evidence suggests that black rice anthocyanins positively modulate gut microbiota composition, potentially improving overall gut health. The incorporation of anthocyanin-rich extracts into various food products, such as bread and beverages, underscores their potential as functional ingredients. This review provides valuable insights into the health benefits associated with rice anthocyanins and identifies areas for future research to optimize their application in functional foods aimed at managing metabolic health.

The fermentation of whey protein and mulberry polyphenols by forming protein-phenolic adducts: Improved digestions

The impacts of forming adduct between whey protein (WP) and mulberry polyphenol (MP) on the digestion and fermentation of WP and MP were investigated using an in vitro model. The results showed that MP increased the in vitro antioxidant capacity of WP digestive products. After forming adduct the total extractable phenolic content of MP dropped from 440.20 mg GAE/g to 21.53 mg GAE/g. The total extractable phenolic content of WP-MP group decreased from 21.53 mg GAE/g to 11.77 mg GAE/g after the oral digestion, then slightly increased to 12.43 after the gastric digestion and continuously increased to 20.43 mg GAE/g after the intestinal digestion. Extractable individual phenolic compounts exhibited the similar tendency, in which cyandin-3-O-glucoside, cyandin-3-O-rutinoside, p-coumaric acid, quercetin and kaempferol were still detectable while protocatechuic and neochlorogenic acid increased after intestinal digestion of WP-MP adduct. Incorporation of MP inhibited the oral and gastric digestion but enhanced the intestinal digestion of WP, and the degree of hydrolysis of WP increased 9.70% after intestinal digestion compared to the control. The fermentation of non-dialyzable residue of WP-MP by gut flora decreased the pH value from 7.18 to 4.82 and increased the proliferation of beneficial bacteria and the production of short-chain fatty acids. These findings indicated that WP-MP adduct increased the digestion of WP and the bioaccessibility of MP, could improve the intestinal health and could be used as a new healthy food ingredient.

Self-assembled nanostructures from rice protein and its fractions: Molecular approaches, physicochemical principles, and functional applications

This review investigates the structural composition and physicochemical properties of rice protein (RP) and their functional applications, unraveling the molecular self-assembly approaches of rice protein isolates (RPI), rice protein hydrolysates (RPH), and their different fractions. RPI complexes with polysaccharides through both non-covalent (electrostatic, hydrogen bonding, hydrophobic and π-interactions) and covalent interactions (Schiff base and enzymatic reactions), whereas with polyphenols, it forms colloidal structures mainly through non-covalent forces. After enzymatic hydrolysis and chain segment reorganization, RPH exhibits enhanced interfacial activity and self-assembles into stable nanostructures, with applications in encapsulation and delivery of bioactive compounds. Owing to variations in conformation and amino acid composition, different fractions of RP can assemble into multilevel structures, including nanofibrils, branching clusters, and spherical nanoparticles, under specific environmental conditions. An in-depth exploration of these self-assembly principles can greatly enhance the physicochemical and structural properties of RP, thereby paving the way for a wide range of functional applications.

Effect of Ultrasound Time on Structural and Gelling Properties of Pea, Lupin, and Rice Proteins

Plant proteins are garnering interest due to the growing demand for plant-based products, but their functionality in gel-based foods remains limited. Ultrasound (US) technology may improve the technological properties of proteins. Thus, the effect of US treatment time (0-15 min) on the structure and gelling properties of pea, lupin, and rice proteins was evaluated. The results showed that the whiteness (~60%) of all freeze-dried proteins remained unchanged (p > 0.05), regardless of the US time. However, FT-IR analysis revealed progressive reductions in α-helix and β-sheet for pea and lupin proteins (~50%) with US time, indicating partial unfolding. In addition, microstructure analysis showed an ~80% reduction in aggregate size for these proteins, while rice protein exhibited minimal changes. Conversely, weak gels were formed with pea and lupin proteins treated after 5 and 10 min of US, respectively, whereas rice protein did not form gels. Furthermore, US treatment time significantly increased (p < 0.05) the mechanical moduli, resulting in more structured gels after longer treatment times (tan δ ~0.3 at 15 min of US). These findings suggest that US treatment enhances the gelling properties of pea and lupin proteins, making them more suitable for plant-based food applications such as yogurt or desserts.

Soy protein-gellan gum noncovalent complexes stabilized emulsion: Effect of heating and pH on emulsion stability

This paper investigated the effects of heating and pH on the stability of emulsions of non-covalent complexes of gellan gum (GG) and soy protein isolate (SPI). As a result, the GG-SPI complexes stabilized emulsion exhibited a minimum emulsion particle size (945 ± 23 nm), a maximum absolute values of zeta-potential (-32.7 ± 0.81 mV), the highest values of emulsion activity index (EAI) and stability index (ESI) (132 ± 4.7 min) when emulsion was prepared under the following conditions: oil phase ratio of 18 %, polysaccharide-protein proportion of 1:8 (w/w), homogeneous pressure at 80 MPa and homogeneous time at 4 min. GG-SPI emulsion had the best emulsification performance at pH 9.0 and 75 °C owing to the protein defolding occurred, the content of α-Helix increased, hydrophobic groups were exposed, and the number of negative groups on the surface of proteins increased under the high pH and high temperature conditions. The experimental results revealed the key role of heating and pH treatment for protein emulsion stability regulation, which will enrich the application of gellan gum in soy protein emulsions and provide an important theoretical basis for the future application of emulsion modification.

Foxtail millet prolamin-pectin nanoparticles enhanced the stability and bioavailability of β-sitosterol

Herein, β-sitosterol-loaded foxtail millet prolamin (FMP)-pectin composite nanoparticles (FSNs) were successfully produced using an antisolvent precipitation method to encapsulate β-sitosterol and improve its bioaccessibility. Results indicated that the nanoparticles prepared at a FMP-to-pectin mass ratio of 10:2 not only showed lower particle size (401.7 ± 14.7 nm, p < 0.05) and higher net zeta potential (-33.3 ± 6.1 mV, p < 0.05) but also exhibited higher encapsulation efficiency (81.5 % ± 0.3 %, p < 0.05). FSNs successfully encapsulated β-sitosterol through electrostatic and hydrophobic interactions and hydrogen bonding. β-sitosterol changed from a crystalline to an amorphous state. Meanwhile, FMP-pectin composite nanoparticles (FNs) and FSNs displayed similar irregular lamellar structures and exhibited excellent physical stability at different environments (pH > 4, salt ions <100 mM, different temperatures and storage at 4 °C). The simulated digestion result showed that FSNs could target the release of β-sitosterol at the intestinal stage with a release rate of 72.23 ± 1.19 % (p < 0.05). Moreover, the bioaccessibility of β-sitosterol in FSNs significantly increased by about 68.58 ± 2.39 % (p < 0.05) compared with free β-sitosterol. Nonetheless, this study provided a novel β-sitosterol delivery system based on FMP-pectin complexes with a broad prospect in the processing of food, pharmaceuticals and nutrition.

Functional, structural, and rheological properties of the complexes containing sunflower petal extract with dairy and plant-based proteins

This study aims to investigate the impact of sunflower petal extract (SFE) on the functional and structural properties of sodium caseinate and chickpea proteins. For this purpose, 3.5 % of sodium caseinate solution and 3.5 % of protein extracted from chickpea powder were prepared in phosphate buffer (pH = 7). SFE was used at different concentrations, from 1 to 3 % in different protein solutions and functional, structural and rheological properties were measured. The results revealed that complexation of SFE with different proteins can enhance the antioxidant, foaming properties, solubility, emulsion activity, emulsion stability, viscoelastic behavior, and can decrease surface hydrophobicity. FTIR and docking results showed that the most bonding type was non-covalent bonds. Major phenolic compounds containing heliannone A, B, and kaempferol had strong affinity with sodium caseinate, and then chickpea protein. Therefore, the results demonstrated that SFE and its complexes had appropriate emulsifying properties that reduces interfacial tension in the water/oil interface.

Effects of polyphenols from Tasmannia lanceolata on structural, emulsifying, and antioxidant properties of pea protein

The effects of polyphenols from Tasmanian pepper (Tasmannia Lanceolata) leaf and berry on the functional properties of pea protein were investigated in flaxseed oil-in-water emulsions. Phenolic acids and flavonols in Tasmanian pepper leaf with smaller molecular weights led to stronger non-covalent interactions with pea protein, while anthocyanins from Tasmanian pepper berry induced protein aggregation under acidic condition and co-existed with proteins in neutral and alkaline conditions. The total phenolic content was significantly increased with incorporation of polyphenols from Tasmanian pepper leaf (334.94-445.92 μg/mL) and berry (72.89-153.03 μg/mL) to pea protein (4.19-15.59 μg/mL). The oxidative stability of emulsions at pH 3 and 7 was enhanced, reducing TBARS value from 1.54 to 2.68 mg MDA/kg in pea protein to 0.56-0.85 mg MDA/kg after 2 weeks storage. These findings illustrated the distinct interactions between pea protein and different polyphenols from Tasmanian pepper leaf and berry to enhance the antioxidant capacity of pea protein.

Recent advances in the plant protein-polyphenol interactions for the stabilization of emulsions

Proteins from plant sources including legumes, cereals and oilseeds are gaining attention due to their suitability for sustainable production, functionality, and positive consumer perception. On the other hand, polyphenols (PPs) are receiving considerable attention as natural ingredients in the human diet due to their potent antioxidant and anti-inflammatory properties. Recent studies indicate that the emulsifying properties of plant proteins (PLPs) can be improved after modification through covalent and/or non-covalent interactions with PPs due to the changes in the conformation and/or the surface chemistry of the proteins. Complexes formed between PLPs-PPs can serve as innovative ingredients for developing novel food products with modified textural properties. Also, Pickering emulsions, multiple emulsions, multilayer emulsions, nanoemulsions, and high internal phase emulsions can be stabilized by such systems to deliver bioactive compounds. This paper reviews the most recent research on the PLP-PP interactions and their role in the stabilization of various emulsion-based systems. A special emphasis is given to modifying the structure and functionality of PLPs and PPs. The challenges and opportunities of applying PLP-PP interactions in emulsion-based systems are also highlighted.

Soy protein-polyphenols conjugates interaction mechanism, characterization, techno-functional and biological properties: An updated review

Soy protein is a promising nutritional source with improved functionality and bioactivities due to conjugation with polyphenols (PP)-the conjugates between soy protein and PP held by covalent and noncovalent bonds. Different approaches, including thermodynamics, spectroscopy, and molecular docking simulations, can demonstrate the outcomes and mechanism of these conjugates. The soy protein, PP structure, matrix properties (temperature, pH), and interaction mechanism alter the ζ-potential, secondary structure, thermal stability, and surface hydrophobicity of proteins and also improve the techno-functional properties such as gelling ability, solubility, emulsifying, and foaming properties. Soy protein-PP conjugates also reveal enhanced in vitro digestibility, anti-allergic, antioxidant, anticancer, anti-inflammatory, and antimicrobial activities. Thus, these conjugates may be employed as edible film additives, antioxidant emulsifiers, hydrogels, and nanoparticles in the food industry. Future research is needed to specify the structure-function associations of soy protein-PP conjugates that may affect their functionality and application in the food industry.

The effect of rice protein-polyphenols covalent and non-covalent interactions on the structure, functionality and in vitro digestion properties of rice protein

The characteristics of the crosslinking between rice protein (RP) and ferulic acid (FA), gallic acid (GA), or tannin acid (TA) by covalent binding of Laccase and non-covalent binding were evaluated. The RP-polyphenol complexes greatly improved the functionality of RP. The covalent effect with higher polyphenol binding equivalence showed higher emulsion activity than the non-covalent effect. The solubility, and antioxidant activity of covalent binding were higher than that of non-covalent binding in the RP-FA group, but there was a contrasting behavior in the RP-GA group. The RP-FA was most soluble in conjugates, while the RP-GA had the highest solubility in mixtures. It was found that the covalent complexes were more stable in the intestinal tract. The content of polyphenols in the RP-TA group was rapidly increased at the later intestinal digestion, which indicated the high polyphenol-protective effect in this group. Meanwhile, the RP-TA group showed high reducing power but low digestibility.

Epigallocatechin gallate modification of physicochemical, structural and functional properties of egg yolk granules

The aim of this study was to prepare protein-polyphenol covalent complexes by treating egg yolk granules (EYG) with alkali in the presence of epigallocatechin gallate (EGCG) and characterize the physicochemical, structural, and functional properties of these covalent complexes. Results revealed that the optimal covalent binding occurred when the concentration of EGCG reached 0.15% (w/w), resulting in a grafting rate of 1.51 ± 0.03%. As the amount of EGCG increased, corresponding increases were observed in the particle size and ζ-potential of the complexes, thereby enhancing their stability. Furthermore, our analysis using fluorescence spectroscopy, FTIR, SEM, and SDS-PAGE collectively demonstrated the formation of a covalent complex between EYG and EGCG. Notably, the covalent complexes exhibited improved antioxidant activity and emulsifying properties. Overall, this study establishes a theoretical framework for the future practical application of EYG, emphasizing the potential of EGCG to modify its structural and functional characteristics.

A comprehensive review on the recent trends in extractions, pretreatments and modifications of plant-based proteins

Plant-based proteins offer sustainable and nutritious alternatives to animal proteins with their techno-functional attributes influencing product quality and designer food development. Due to the inherent complexities of plant proteins, proper extraction and modifications are vital for their effective utilization. This review highlights the emerging sources of plant-based proteins, and the recent statistics of the techniques employed for pretreatment, extraction, and modifications. The pretreatment, extraction and modification approach to modify plant proteins have been classified, addressed, and the recent applications of such methodologies are duly indicated. Furthermore, this study furnishes novel perspectives regarding the potential impacts of emerging technologies on the intricate dynamics of plant proteins. A thorough review of 100 articles (2018-2024) shows the researchers' keen interest in investigating novel plant proteins and how they can be used; seeds being the main source for protein extraction, followed by legumes. Use of by-products as a protein source is increasing rapidly, which is noteworthy. Protein studies still lack knowledge on protein fraction, antinutrients, and pretreatments. The use of physical methods and their combination with other techniques are increasing for effective and environmentally friendly extraction and modification of plant proteins. Several studies explore the effect of protein changes on their function and nutrition, especially with a goal of replacing ingredients with plant proteins that have improved or enhanced qualities. However, the next step is to investigate the sophisticated modification methods for deeper insights into food safety and toxicity.

Research Progress on the Extraction and Purification of Anthocyanins and Their Interactions with Proteins

Anthocyanins, as the most critical water-soluble pigments in nature, are widely present in roots, stems, leaves, flowers, fruits, and fruit peels. Many studies have indicated that anthocyanins exhibit various biological activities including antioxidant, anti-inflammatory, anti-tumor, hypoglycemic, vision protection, and anti-aging. Hence, anthocyanins are widely used in food, medicine, and cosmetics. The green and efficient extraction and purification of anthocyanins are an important prerequisite for their further development and utilization. However, the poor stability and low bioavailability of anthocyanins limit their application. Protein, one of the three essential nutrients for the human body, has good biocompatibility and biodegradability. Proteins are commonly used in food processing, but their functional properties need to be improved. Notably, anthocyanins can interact with proteins through covalent and non-covalent means during food processing, which can effectively improve the stability of anthocyanins and enhance their bioavailability. Moreover, the interactions between proteins and anthocyanins can also improve the functional characteristics and enhance the nutritional quality of proteins. Hence, this article systematically reviews the extraction and purification methods for anthocyanins. Moreover, this review also systematically summarizes the effect of the interactions between anthocyanins and proteins on the bioavailability of anthocyanins and their impact on protein properties. Furthermore, we also introduce the application of the interaction between anthocyanins and proteins. The findings can provide a theoretical reference for the application of anthocyanins and proteins in food deep processing.

Formation mechanism of quinoa protein hydrolysate-EGCG complexes at different pH conditions and its effect on the protein hydrolysate-lipid co-oxidation in emulsions

This study aimed to investigate the interaction, structure, antioxidant, and emulsification properties of quinoa protein hydrolysate (QPH) complexes formed with (-)-epigallocatechin gallate (EGCG) at pH 3.0 and 7.0. Additionally, the effect of pH conditions and EGCG complexation on protein hydrolysate-lipid co-oxidation in QPH emulsions was explored. The results indicated that QPH primarily interacted with EGCG through hydrophobic interactions and hydrogen bonds. This interaction led to alterations in the secondary structure of QPH, as well as a decrease in surface hydrophobicity and free SH content. Notably, the binding affinity between QPH and EGCG was observed to be higher at pH 7.0 compared to pH 3.0. Consequently, QPH-EGCG complexes exhibited more significant enhancement in antioxidant and emulsification properties at pH 7.0 than pH 3.0. The pH level also influenced the droplet size, ζ-potential, and interfacial composition of emulsions formed by QPH and QPH-EGCG complexes. Compared to QPH stabilized emulsions, QPH-EGCG stabilized emulsions were more capable of mitigating destabilization during storage and displayed fewer lipid oxidation products, carbonyl generation, and sulfhydryl groups and fluorescence loss, which implied better oxidative stability of the emulsions. Furthermore, the QPH-EGCG complexes formed at pH 7.0 exhibited better inhibition of protein hydrolysate-lipid co-oxidation. Overall, these findings provide valuable insights into the potential application of QPH and its complexes with EGCG in food processing systems.

Unveiling the impact of high-pressure processing on anthocyanin-protein/polysaccharide interactions: A comprehensive review

Anthocyanins, natural plant pigments responsible for the vibrant hues in fruits, vegetables, and flowers, boast antioxidant properties with potential human health benefits. However, their susceptibility to degradation under conditions such as heat, light, and pH fluctuations necessitates strategies to safeguard their stability. Recent investigations have focused on exploring the interactions between anthocyanins and biomacromolecules, specifically proteins and polysaccharides, with the aim of enhancing their resilience. Notably, proteins like soy protein isolate and whey protein, alongside polysaccharides such as pectin, starch, and chitosan, have exhibited promising affinities with anthocyanins, thereby enhancing their stability and functional attributes. High-pressure processing (HPP), emerging as a non-thermal technology, has garnered attention for its potential to modulate these interactions. The application of high pressure can impact the structural features and stability of anthocyanin-protein/polysaccharide complexes, thereby altering their functionalities. However, caution must be exercised, as excessively high pressures may yield adverse effects. Consequently, while HPP holds promise in upholding anthocyanin stability, further exploration is warranted to elucidate its efficacy across diverse anthocyanin variants, macromolecular partners, pressure regimes, and their effects within real food matrices.

Esterified wheat bran: Physicochemical properties, structure and quality improvement of Chinese steamed bread during refrigerated storage

To develop the application of wheat bran and improve the nutrition and anti-staling capacity of Chinese steamed bread (CSB), oleic acid-esterified wheat bran (OWB) was prepared by esterification of wheat bran with oleic acid, and its physicochemical properties, structure, and quality improvement for CSB during refrigerated storage were investigated. The hydrophilic-lipophilic balance value of OWB was 16.0, the maximum degree of substitution was 0.146, and its emulsifying capacity was similar to that of glycerol monostearate. The starch gelatinization degree of CSB containing 3 % OWB and the control decreased by 19.55 % and 27.12 % within 7 days of refrigerated storage, respectively, while the hardness of CSB with OWB was lower than that with wheat bran. OWB inhibited starch recrystallization and increased bound water in the corresponding CSB, which effectively delayed starch retrogradation. OWB had a positive emulsifying capacity and showed potential as a functional material for preventing retrogradation of starch-based foods.

Polyphenol nanoparticles based on bioresponse for the delivery of anthocyanins

Anthocyanin (AN) has good antioxidant and anti-inflammatory bioactivities, but its poor biocompatibility and low stability limit the application of AN in the food industry. In this study, core-shell structured carriers were constructed by noncovalent interaction using tannic acid (TA) and poloxamer 188 (F68) to improve the biocompatibility, stability and smart response of AN. Under different treatment conditions, TA-F68 and AN were mainly bound by hydrophobic interaction. The PDI is less than 0.1, and the particle size of nanoparticles (NPs) is uniform and concentrated. The retention of the complex was 15.50 % higher than that of AN alone after 9 d of light treatment. After heat treatment for 180 min, the retention rate after loading was 13.87 % higher than that of AN alone. The carrier reduce the damage of AN by the digestive environment, and intelligently and sustainedly release AN when the esterase is highly expressed. In vitro studies demonstrated that the nanocarriers had good biocompatibility and significantly inhibited the overproduction of reactive oxygen species induced by oxidative stress. In addition, AN-TA-F68 has great potential for free radical scavenging at sites of inflammation. In conclusion, the constructed nano-delivery system provides a potential application for oral ingestion of bioactive substances for intervention in ulcerative colitis.

Ion presence during thermal processing modulates the performance of rice albumin/anthocyanin binary system

Thermal processing with salt ions is widely used for the production of food products (such as whole grain food) containing protein and anthocyanin. To date, it is largely unexplored how salt ion presence during thermal processing regulates the practical performance of protein/anthocyanin binary system. Here, rice albumin (RA) and black rice anthocyanins (BRA) were used to prepare RA/BRA composite systems as a function of temperature (60-100 °C) and NaCl concentration (10-40 mM) or CaCl2 concentration (20 mM). It was revealed that the spontaneous complexing reaction between RA and BRA was driven by hydrophobic interactions and hydrogen bonds and becomes easier and more favorable at a higher temperature (≤90 °C), excessive temperature (100 °C), however, may result in the degradation of BRA. Moreover, the salt ion presence during thermal processing may bind with RA and BRA, respectively, which could restrict the interaction between BRA and RA. Additionally, the inclusion of Na+ or Ca2+ at 20 mM endowed the binary system with strengthened DPPH radical scavenging capacity (0.95 for Na+ and 0.99 for Ca2+). Notably, Ca2+ performed a greater impact on the stability of the system than Na+.

Soy protein isolate-catechin complexes conjugated by pre-heating treatment for enhancing emulsifying properties: Molecular structures and binding mechanisms

This study aimed to investigate the impact of different pre-heating temperatures (ranging from 40 °C to 80 °C) on the interactions between soy protein isolate (SPI) and catechin to effectively control catechin encapsulation efficiency and optimize the emulsifying properties of soy protein isolate. Results showed that optimal heat treatment at 70 °C improved catechin encapsulation efficiency up to 93.71 ± 0.14 %, along with the highest solubility, enhanced emulsification activity index and improved thermal stability of the protein. Multiple spectroscopic techniques revealed that increasing pretreatment temperature (from 40 °C to 70 °C) altered the secondary structures of SPI, resulting in a more stable unfolded structure for the composite system with a significant increase in α-helical structures and a decrease in random coil and β-sheet structures. Moreover, optimal heat treatment also leads to an augmentation of free sulfhydryl groups within complex as well as exposure of more internal chromophore amino acids on molecular surface. Size-exclusion high-performance liquid chromatography and SDS-PAGE analysis indicated that the band intensity of newly formed high-molecular-weight soluble macromolecules (>180 kDa) increased as the pre-heating temperature rose. Furthermore, fluorescence spectroscopy and molecular docking analysis suggest that hydrophobic and covalent interactions were involved in complex formation, which intensified with increasing temperature.

Physico-chemical, functional, and structural properties of un-defatted, cold and hot defatted yellow lupin protein isolates

This study investigates the structure, physico-chemical and functional properties of yellow lupin isolate protein (YLPI) obtained by different processes (conventional wet and purely aqueous fractionation) from un-defatted (YLPIU), and hot (YLPIHD) and cold (YLPICD) defatted flour. The defatting process modified the physical, structural and functional characteristics of lupin protein isolates. Indeed, a decrease of α-helix, free sulfhydryl groups amount and an increase of disulfide bond levels were observed for defatted samples, improving their emulsifying stability. The defatting process exposes the hydrophobic groups present within the YLPI, which increases total sulfhydryl content and protein surface hydrophobicity. Hot and cold defatting induced a decrease in turbidity, water-holding capacity, oil adsorption capacity, tapped and poured bulk densities. In addition, the defatting process changed the particle size of protein isolates that induced changes in their viscosity. Tryptophan spectra and protein surface hydrophobicity indicated that YLPICD and YLPIHD underwent structural conformational change during the defatting process.

Effect of enzymolysis combined with Maillard reaction treatment on functional and structural properties of gluten protein

In this work, the modified gluten was prepared by enzymolysis combined with Maillard reaction (MEG), and its functional and structural properties were investigated. The result showed that the maximum foamability of MEG was 19.58 m2/g, the foam stability was increased by 1.8 times compared with gluten, and the solubility and degree of graft were increased to 44.4 % and 28.1 % at 100 °C, whereas the content of sulfhydryl group decreased to 0.81 μmol/g. The scavenging ability on ABTS+radical and DPPH radical of MEG was positively correlated with reaction temperature, and the maximum values were 86.57 % and 71.71 % at 140 °C, respectively. Furthermore, the fluorescence quenching effect of tryptophan and tyrosine residues was enhanced, while the fluorescence intensity decreased with the temperature increase. Scanning electron microscopy revealed that the surface of enzymatically hydrolyzed-gluten became smooth and the cross section became straightened, while MEG turned smaller and irregular approaching a circular structure. FT-IR spectroscopy showed that enzymatic hydrolysis promoted the occurrence of more carbonyl ammonia reactions and the formation of precursors of advanced glycosylation end products. These results provide a feasible method for improving the structure and functional properties of gluten protein.

Comparative study of dietary phenols with Tartary buckwheat protein (2S/13S): impact on structure, binding sites and functionality of protein

BACKGROUND

This research was to investigate the interaction mechanism between 2S albumin and 13S globulin (2S and 13S, the most important storage proteins in Tartary buckwheat seeds) and three phenols (rutin, quercetin and myricetin) regarding the structural and antioxidant properties of their complexes.

RESULTS

There are differences in the binding affinity of phenols for 2S and 13S. Rutin had a higher binding affinity for 2S, myricetin had a higher binding affinity for 13S, and 13S exhibited a higher affinity toward phenols than did 2S. Binding with phenols significantly changed the secondary and tertiary structures of 2S and 13S, decreased the surface hydrophobic value and enhanced the antioxidant capacity. Molecular docking and isothermal titration calorimetry showed that the binding processes were spontaneous and that there were hydrogen bonds, hydrophobic bonds and van der Waals force interactions between phenols and proteins.

CONCLUSION

These findings could provide meaningful guidance for the further application of buckwheat protein complex. © 2023 Society of Chemical Industry.

The biological activity, functionality, and emulsion stability of soybean meal hydrolysate-proanthocyanidin conjugates

The use of by-product hydrolysates as functional ingredients in food production is becoming more widespread. We hypothesized that the covalent binding of proanthocyanidin (PC) to soybean meal hydrolysates (SMHs) will improve the biological activity and function of the SMHs. Accordingly, we investigated the structure, antioxidant activity, and emulsion stability of SMHs after covalent conjugation with different concentrations of PC. An increase in PC addition resulted in the development of more high-molecular-weight SMHs-PC conjugates (40 kDa). The observed increase in the random coil content indicated that greater unfolding and disordered structure formation occurred with increasing PC addition. In addition, the fluorescence intensity and surface hydrophobicity of the SMHs increased, suggesting the presence of free amino acids, which likely contributed to the antioxidant activity and emulsifying properties of the SMHs. Addition of 3.0 mg/mL PC gave the SMHs-PC conjugates the highest antioxidant activity (ABTS+ and DPPH radical scavenging capacities of 89.08 ± 0.47 and 40.90 ± 1.53%, respectively) and emulsifying activity index (79.13 ± 2.80 m2/g), which may be attributed to protein unfolding and maximization of the polyphenol content when PC was covalently bound to the SMHs. Moreover, the SMHs-PC emulsion with 2.0 mg/mL PC showed the smallest particle size and highest viscosity, presenting promising potential as an emulsifier with high biological activity in food.

Hemp seed globulin-alginate nanoparticles for encapsulation of Cannabisin A with enhanced colloidal stability and antioxidant activity

This study develops hemp seed globulin (GLB)-alginate (ALG) nanoparticles (GANPs) for Cannabisin A (CA) stabilization under environmental stress and during pepsin digestion. The optimal GLB: ALG mass ratio of 1: 1.5 was determined for GANPs formation at pH 3.5, resulting in a high yield of 95.13 ± 0.91 %, a ζ-potential of -35.73 ± 1.04 mV, a hydrodynamic diameter of 470.67 ± 11.36 nm, and a PDI of 0.298 ± 0.016. GANPs were employed to encapsulate CA, achieving a high loading capacity of 13.48 ± 0.04 μg mg-1. FTIR analysis demonstrated that the formation of CA-GLB-ALG nanoparticles (CGANPs) involves electrostatic interactions, hydrogen bonding, and hydrophobic interactions. XRD and DSC analyses revealed that CA is amorphous within the CGANPs. CGANPs demonstrated remarkable dispersion stability as well as resistance to high ionic strength and high-temperature treatments, indicating their potential as efficient hydrophobic drug-delivery vehicles. When compared to free CA, CA coated within CGANPs displayed greater DPPH/ABTS scavenging activity. Furthermore, the ALG-shelled nanoparticles protected GLB from pepsin digestion and slowed the release of CA throughout the release process, extending their stay on the intestinal wall mucosa. These findings imply that CGANPs is an ideal delivery vehicle for CA as they may expand the application of CA in food items.

Interaction and binding mechanism of ovalbumin with cereal phenolic acids: improved structure, antioxidant activity, emulsifying and digestion properties for potential targeted delivery systems

Ovalbumin (OVA) has been considered as a nutrient carrier for bioactive, which has high nutrition value and multiple properties. Recently, proteins-phenolic acids composite delivery systems have received widespread attention. Therefore, this research aimed to investigate the interaction between OVA and cereal phenolic acids (CPA) to establish delivery systems for bioactive. Spectroscopy results have found that CPA generated complexes with OVA, causing the microenvironment changes of OVA. Ferulic acid (FA), p-coumaric acid (CA), vanillic acid (VA), syringic acid (SY), sinapic acid (SI), and protocatechuic acid (PA) not only quenched the intrinsic fluorescence of OVA, but also altered protein microenvironment. Further investigation showed these complexes were formed by static quenching mode, while hydrogen bond and hydrophobic interaction were dominant binding forces. Meanwhile, the interaction decreased α-helix contents and increased β-sheet contents, leading to conformational changes in OVA. Besides, OVA/CPA complexes displayed an increase in hydrophobicity with a reduce in free-SH. After combination with FA, SY, CA, VA, SI, PA, it was found that all formed complexes had superior solubility, emulsifying and antioxidant activities than native OVA. Among them, OVA-PA exhibited the highest emulsifying activity index and emulsion stability index values (36.4 ± 0.39 m2/g and 60.4 ± 0.94 min) and stronger antioxidant activities. Finally, the combination with phenolic acids further improved the digestion efficiency in vitro of OVA. The OVA-CPA complexes showed improved properties for excellent delivery systems. Overall, OVA-CPA complexes could be a good carrier for bioactive, which provided valuable avenues in target delivery system application.

Plant-Based Protein-Phenolic Interactions: Effect on different matrices and in vitro gastrointestinal digestion

This review summarizes the literature on the interaction between plant-based proteins and phenolics. The structure of the phenolic compound, the plant source of proteins, matrix properties (pH, temperature), and interaction mechanism (covalent and non-covalent) change the secondary structure, ζ-potential, surface hydrophobicity, and thermal stability of proteins as well as their functional properties including solubility, foaming, and emulsifying properties. Studies indicated that the foaming and emulsifying properties may be affected either positively or negatively according to the type and concentration of the phenolic compound. Protein digestibility, on the other hand, differs depending on (1) the phenolic concentration, (2) whether the food matrix is ​​solid or liquid, and (3) the state of the food-whether it is heat-treated or prepared as a mixture without heat treatment in the presence of phenolics. This review comprehensively covers the effects of protein-phenolic interactions on the structure and properties of proteins, including functional properties and digestibility both in model systems and real food matrix.

Protein and Peptide-Based Nanotechnology for Enhancing Stability, Bioactivity, and Delivery of Anthocyanins

Anthocyanin, a unique natural polyphenol, is abundant in plants and widely utilized in biomedicine, cosmetics, and the food industry due to its excellent antioxidant, anticancer, antiaging, antimicrobial, and anti-inflammatory properties. However, the degradation of anthocyanin in an extreme environment, such as alkali pH, high temperatures, and metal ions, limits its physiochemical stabilities and bioavailabilities. Encapsulation and combining anthocyanin with biomaterials could efficiently stabilize anthocyanin for protection. Promisingly, natural or artificially designed proteins and peptides with favorable stabilities, excellent biocapacity, and wide sources are potential candidates to stabilize anthocyanin. This review focuses on recent progress, strategies, and perspectives on protein and peptide for anthocyanin functionalization and delivery, i.e., formulation technologies, physicochemical stability enhancement, cellular uptake, bioavailabilities, and biological activities development. Interestingly, due to the simplicity and diversity of peptide structure, the interaction mechanisms between peptide and anthocyanin could be illustrated. This work sheds light on the mechanism of protein/peptide-anthocyanin nanoparticle construction and expands on potential applications of anthocyanin in nutrition and biomedicine.

Interactions of legume phenols-rice protein concentrate towards improving vegan food quality: Development of a protein-phenols enriched fruit smoothie

Phenol-protein interaction is considered an effective tool to improve the functional properties of vegan proteins. The present work aimed to evaluate the covalent interaction between kidney bean polyphenols with rice protein concentrate and studied their characteristics for quality improvement in vegan-based foods. The impact of interaction on the techno-functional properties of protein was evaluated and the nutritional composition revealed that kidney bean was rich in carbohydrates. Furthermore, a noticeable antioxidant activity (58.11 ± 1.075 %) due to the presence of phenols (5.5 mg GAE/g) was observed for the kidney bean extract. Moreover, caffeic acid and p-Coumaric acid were confirmed using ultra-pressure liquid chromatography and the amount was 194.43 and 0.9272 mg/kg, respectively. A range of rice protein- phenols complexes (PPC0.025, PPC0.050, PPC0.075, PPC0.1, PPC0.2, PPC 0.5, PPC1) were examined and PPC0.2 and PPC0.5 showed significantly (p < 0.05) higher binding efficiency with proteins via covalent interaction. The conjugation reveals changes in physicochemical properties of rice protein, including, reduced size (178.4 nm) and imparted negative charges (-19.5 mV) of the native protein. The presence of amide Ⅰ, Ⅱ, Ⅲ, was confirmed in native protein and protein-phenol complex with vibration bands, particularly at 3784.92, 1631.07, and 1234 cm^-1, respectively. The X-ray diffraction pattern depicted a slight decrease in crystallinity after the complexation and scanning electron microscopy revealed the alteration in morphology from less to improved smoothness and continuous surface characteristics for the complex. Thermo gravimetric analysis revealed high thermal stability of the complex with a maximum weight loss at a temperature range of 400-500 °C. Protein-phenol complex added fruit-based smoothie was developed and it was found to be acceptable in terms of various sensory attributes including color & appearance, textural consistency, and mouthfeel as compared to the control smoothie. Overall, this study provided novel insights to understand the phenol-protein interactions and the possible use of the phenol-rice protein complex in the development of vegan-based food products.

First insights into the binding mechanism and colour effect of the interaction of grape seed 11S globulin with malvidin 3-O-glucoside by fluorescence spectroscopy, differential colorimetry and molecular modelling

Recently, the search for alternative proteins endogenous to grapes to be used as wine colour protecting agents became an important research trend. In this study, the molecular interaction between the grape seed 11S globulin from winemaking by-product and malvidin-3-O-glucoside was investigated by fluorescence, differential colorimetry and molecular modelling. Fluorescence studies revealed the formation of grape seed protein- pigment complex whose KS was 8.5 × 104 M-1 and binding sites, n = 1.3. Malvidin-3-O-glucoside showed darker and more vivid bluish colour of in the presence of 11S globulin, suggesting the flavylium cation protection in a hydrophobic region of the protein. Docking analysis and molecular dynamics simulation indicated that malvidin-3-O-glucoside interacts mainly with the acidic subunit (40 kDa) of the 11S globulin monomer (60 kDa). An average of two hydrogen bonds and Van der Wall forces were the main interaction forces found for the protein-pigment complex, whose stability was confirmed by root-means-square deviation.

Interaction of preheated whey protein isolate with rose anthocyanin extracts in beverage model system: Influence on color stability, astringency and mechanism

Preheating proteins have the potential to improve anthocyanin stability. Our aim was to investigate the effect of preheated whey protein isolate (WPI) on the color stability and astringency of the beverage model system in the presence of rose anthocyanin extracts (RAEs), and to explore the mechanism of interaction between preheated WPI and RAEs. The secondary structure, particle size and transparency of WPI were obviously changed by preheating. WPI preheated at 100°C  (WPI100) could effectively improve the color stability of RAEs in the beverage model system. Importantly, the WPI100-RAEs in the beverage model system exhibited the smallest particle size and the weakest astringency effect. In addition, different preheated WPIs could interact with RAEs non-covalently, and the interaction forces are hydrogen bonding and van der Waals forces, among which WPI100 had the strongest binding ability to RAEs. These results will provide a new insight into the development of protein-anthocyanin beverages.

Development, Characterization and Resveratrol Delivery of Hollow Gliadin Nanoparticles: Advantages over Solid Gliadin Nanoparticles

Hollow nanoparticles have attracted extensive attention due to their advantages such as high loading capacity and superior stability. However, the complexity of the preparation process and harmfulness of the used raw materials have limited their application in the food field. Based on this, hollow gliadin nanoparticles (HGNPs) were developed using a Na₂CO₃ sacrificial template method. The findings of this study suggested that HGNPs could be regarded as a delivery system for resveratrol (Res) and they exhibited excellent delivery performance. Compared with solid gliadin nanoparticles (SGNPs), the HGNPs displayed smaller particle sizes, better physical stability, higher encapsulation efficiency, stronger resistance to ultraviolet light and a more sustained release of Res in the gastrointestinal tract. This work is of practical significance for the development and utilization of protein-based nanoparticles with hollow structures as a delivery system for sensitive bioactives.

Rectifying disorder of extracellular matrix to suppress urethral stricture by protein nanofilm-controlled drug delivery from urinary catheter

Urethral stricture secondary to urethral injury, afflicting both patients and urologists, is initiated by excessive deposition of extracellular matrix in the submucosal and periurethral tissues. Although various anti-fibrotic drugs have been applied to urethral stricture by irrigation or submucosal injection, their clinical feasibility and effectiveness are limited. Here, to target the pathological state of the extracellular matrix, we design a protein-based nanofilm-controlled drug delivery system and assemble it on the catheter. This approach, which integrates excellent anti-biofilm properties with stable and controlled drug delivery for tens of days in one step, ensures optimal efficacy and negligible side effects while preventing biofilm-related infections. In a rabbit model of urethral injury, the anti-fibrotic catheter maintains extracellular matrix homeostasis by reducing fibroblast-derived collagen production and enhancing metalloproteinase 1-induced collagen degradation, resulting in a greater improvement in lumen stenosis than other topical therapies for urethral stricture prevention. Such facilely fabricated biocompatible coating with antibacterial contamination and sustained-drug-release functionality could not only benefit populations at high risk of urethral stricture but also serve as an advanced paradigm for a range of biomedical applications.

Enhanced TSG stability through co-assembly with C3G: the mechanism behind processing Polygonum multiflorum Thunb with black beans via supramolecular analysis

Elucidating the underlying mechanism of the processing of Chinese herbal medicine (CHM) is crucial and also challenging for the modernization of Traditional Chinese Medicine (TCM). Herein, inspired by the traditional method for processing the Chinese herb Polygonum multiflorum (PM) Thunb with excipient black beans, the representative herbal components trans-2,3,5,4'-tetrahydroxystilbene 2-O-β-D-glucopyranoside (TSG) and cyanidin-3-O-β-glucoside (C3G) from each herbal medicine were selected to investigate the processing mechanism at the supramolecular level. The co-assemblies of TSG/C3G were found to be formed, and their structure was characterized by electronic microscopy and a small angle X-ray scattering (SAXS) technique. In addition, the supramolecular interactions between TSG and C3G were fully probed with UV-Vis, fluorescence, XRD, and NMR spectroscopy. Molecular dynamics were further performed to simulate the assembly processes of TSG and C3G. Notably, the formation of TSG/C3G co-assemblies was found to significantly enhance the stability of TSG against light, Fe3+, and simulated intestinal fluids. The co-assembly of TSG and C3G that leads to supramolecular aggregates discovered here may imply the underlying mechanism of processing PM with black beans. Our results may also suggest that a new effective form of TCM is supramolecular aggregates rather than each component.

Improving the biological activity, functional properties, and emulsion stability of soybean meal hydrolysate via covalent conjugation with polyphenol

The use of by-products as functional components in food production is gaining popularity. This study investigated the structure, biological activity, interaction force, and emulsion stability of soybean meal hydrolysate (SMHs) after covalent conjugation with proanthocyanidin (PC), epigallocatechin (EGCG), gallic acid (GA), and caffeic acid (CA). SDS-PAGE confirmed the formation of SMHs-polyphenol conjugates. Structural analysis indicates unfolding and disordered-structure formation. This transformation directly influenced the antioxidant activity and emulsification of SMHs. The antioxidant and emulsifying properties of all covalent complexes were superior to SMHs, in order of SMHs-PC, SMHs-EGCG, SMHs-GA, and SMHs-CA. Among, SMHs-PC conjugates displayed the highest antioxidant activity (ABTS^•+ and DPPH radical scavenging capacities of 89.33% and 52.71%, respectively), total polyphenol content (235.10 mg/g), and emulsification activity (EAI) and stability (ESI) values (109.27 m²/g and 135.05 min, respectively). Moreover, SMHs-PC emulsion showed the smallest particle size (467.20 nm), highest viscosity (520.19 Pa.s), highest protein adsorption (94.33%), and lowest release rate of free fatty acids (FFAs) (18.61%) after digestion. These results provided valuable information for the use of modified SMHs as emulsifiers, which is a promising approach for increasing the value of soybean meal.

Interaction between Chinese quince fruit proanthocyanidins and bovine serum albumin: Antioxidant activity, thermal stability and heterocyclic amine inhibition

Heterocyclic amines (HCAs) are carcinogenic and mutagenic substances produced in fried meat. Adding natural antioxidants (e.g., proanthocyanidins (PAs)) is a common method to reduce HCAs; however, the interaction between the PAs and protein can affect the inhibitory efficacy of PAs on the formation of HCAs. In this study, two PAs (F1 and F2) with different degrees of polymerization (DP) were extracted from Chinese quince fruits. These were combined with bovine serum albumin (BSA). The thermal stability, antioxidant capacity and HCAs inhibition of all four (F1, F2, F1-BSA, F2-BSA) were compared. The results showed that F1 and F2 interact with BSA to form complexes. Circular dichroism spectra indicate that complexes had fewer α-helices and more β-sheets, β-turns and random coils than BSA. Molecular docking studies indicated that hydrogen bonds and hydrophobic interactions are the forces holding the complexes together. The thermal stabilities of F1 and, particularly, F2 were stronger than those of F1-BSA and F2-BSA. Interestingly, F1-BSA and F2-BSA showed increased antioxidant activity with increasing temperature. F1-BSA's and F2-BSA's HCAs inhibition was stronger than F1 and F2, reaching 72.06 % and 76.3 %, respectively, for norharman. This suggests that PAs can be used as natural antioxidants for reducing the HCAs in fried foods.

A review of the structure, function, and application of plant-based protein-phenolic conjugates and complexes

Interactions between plant-based proteins (PP) and phenolic compounds (PC) occur naturally in many food products. Recently, special attention has been paid to the fabrication of PP-PC conjugates or complexes in model systems with a focus on their effects on their structure, functionality, and health benefits. Conjugates are held together by covalent bonds, whereas complexes are held together by noncovalent ones. This review highlights the nature of protein-phenolic interactions involving PP. The interactions of these PC with the PP in model systems are discussed, as well as their impact on the structural, functional, and health-promoting properties of PP. The PP in conjugates and complexes tend to be more unfolded than in their native state, which often improves their functional attributes. PP-PC conjugates and complexes often exhibit improved in vitro digestibility, antioxidant activity, and potential allergy-reducing activities. Consequently, they may be used as antioxidant emulsifiers, edible film additives, nanoparticles, and hydrogels in the food industry. However, studies focusing on the application of PP-PC conjugates and complexes in real foods are still scarce. Further research is therefore required to determine the structure-function relationships of PP-PC conjugates and complexes that may influence their application as functional ingredients in the food industry.

Polyphenol extracts from Ascophyllum nodosum protected sea cucumber (Apostichopus japonicas) body wall against thermal degradation during tenderization

To retard the protein degradation during sea cucumber processing, polyphenol extracts from Ascophyllum nodosum (PhE) was used as a potential antioxidant to maintain the structural integrity of sea cucumber body wall. Accordingly, the protection effects of PhE (0, 0.5, 1.0 and 1.5 mg PhE/g SFBW) against thermal degradation of the solid fragments of body wall (SFBW) have been investigated in order to evaluate their impact on the oxidation level and structural changes. Electronic Spin Resonance results showed that PhE could significantly inhibit the occurrence of oxidation by scavenging the free radicals. The effect of PhE on chemical analysis of soluble matters in SFBW was characterized by SDS-PAGE and HPLC. Compared with thermally treated SFBW, samples with PhE presented a decrease in protein dissolution. Thermal treatment resulted in the disintegration of collagen fibrils and fibril bundles in SFBW samples, while the density of collagen fibrils was increased, and the porosity decreased in samples with PhE. The results of FTIR and intrinsic tryptophan fluorescence confirmed that the structures of SFBW were modified by PhE. Besides, the denaturing temperature and decomposition temperature were both improved with the addition of PhE. These results suggested that PhE appeared to have a positive effect on lowering oxidation and improving thermostability and structural stability of SFBW, which could provide a theoretical basis for protecting sea cucumber body wall against degradation during thermal tenderization.

Impacts of Proanthocyanidin Binding on Conformational and Functional Properties of Decolorized Highland Barley Protein

The impacts of interaction between proanthocyanidin (PC) and decolorized highland barley protein (DHBP) at pH 7 and 9 on the functional and conformational changes in DHBP were investigated. It was shown that PC strongly quenched the intrinsic fluorescence of DHBP primarily through static quenching. PC and DHBP were mainly bound by hydrophobic interactions. Additionally, free sulfhydryl groups and surface hydrophobicity obviously decreased in DHBP after combining with PC. The zeta potential of DHBP-PC complexes at pH 7 increased significantly. A change in the structure of DHBP was caused by interactions with PC, resulting in an increase in the number of β-sheets, a decrease in the number of α-helixes, and a spectral shift in the amide Ⅱ band. Furthermore, the presence of PC enhanced the foaming properties and antioxidant activity of DHBP. Overall, this study suggests that DHBP-PC complexes at pH 7 could be designed as a stable additive, and illustrates the potential applications of DHBP-PC complexes in the food industry.

Investigation of the Effect of Rice Bran Content on the Antioxidant Capacity and Related Molecular Conformations of Plant-Based Simulated Meat Based on Raman Spectroscopy

At present, plant-based simulated meat is attracting more and more attention as a meat substitute. This study discusses the possibility of partial substitution of rice bran (RB) for soybean protein isolate (SPI) in preparing plant-based simulated meat. RB was added to SPI at 0%, 5%, 10%, 15%, and 20% to prepare RB-SPI plant-based simulated meat by the high moisture extrusion technique. RB-SPI plant-based simulated meat revealed greater polyphenol content and preferable antioxidant capacity (DPPH radical scavenging capacity, ABTS scavenging ability, and FRAP antioxidant capacity) compared to SPI plant-based simulated meat. The aromatic amino acids (tryptophan and tyrosine) of RB-SPI plant-based simulated meats tend to be masked first, and then the hydrophobic groups are exposed as RB content increases and the polarity of the surrounding environment increases due to the change in the disulfide conformation of RB-SPI plant-based simulated meats from a stable gauche-gauche-gauche conformation to a trans-gauche-trans conformation.

Covalent and Noncovalent Complexation of Phosvitin and Gallic Acid: Effects on Protein Functionality and In Vitro Digestion Properties

To investigate the effects of different binding modes on the structure, function, and digestive properties of the phosvitin (Pv) and gallic acid (GA) complex, Pv was covalently and noncovalently combined with different concentrations of GA (0.5, 1.5, and 2.5 mM). The structural characterization of the two Pv-GA complexes was performed by Fourier transform infrared, circular dichroism, and LC-MS/MS to investigate the covalent and noncovalent binding of Pv and GA. In addition, the microstructure of the two Pv-GA complexes was investigated by super-resolution microscopy and transmission electron microscopy. The particle size and zeta potential results showed that the addition of GA increased the particle size and the absolute potential of Pv. The determination of protein digestibility, polyphenol content, SH and S-S group levels, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and antioxidant capacity of the digests indicated that noncovalent complexes had greater antioxidant and protective effects on polyphenols. Molecular docking revealed that GA was conjugated with Pv through hydrogen bond interactions.

An updated review on the stability of anthocyanins regarding the interaction with food proteins and polysaccharides

The health benefits of anthocyanins are compromised by their chemical instability and susceptibility to external stress. Researchers found that the interaction between anthocyanins and macromolecular components such as proteins and polysaccharides substantially determines the stability of anthocyanins during food processing and storage. The topic thus has attracted much attention in recent years. This review underlines the new insights gained in our current study of physical and chemical properties and functional properties in complex food systems. It examines the interaction between anthocyanins and food proteins or polysaccharides by focusing on the "structure-stability" relationship. Furthermore, multispectral and molecular computing simulations are used as the chief instruments to explore the interaction's mechanism. During processing and storage, the stability of anthocyanins is generally influenced by the adverse characteristics of food and beverage, including temperature, light, oxygen, enzymes, pH. While the action modes and types between protein/polysaccharide and anthocyanins mainly depend on their structures, the noncovalent interaction between them is the key intermolecular force that increases the stability of anthocyanins. Our goal is to provide the latest understanding of the stability of anthocyanins under food processing conditions and further improve their utilization in food industries. Practical Application: This review provides support for the steady-state protection of active substances.