Soy peptide aggregates formed during hydrolysis reduced protein extraction without decreasing their nutritional value

The enhanced affinity of moderately hydrolyzed whey protein to EGCG promotes the isoelectric separation and unlocks the protective effects on polyphenols

The instability and discoloration of (-)-epigallocatechin-3-gallate (EGCG) constrain its application in functional dairy products. Concurrently, challenges persist in the separation and utilization of whey in the dairy industry. By harnessing the interactions between polyphenols and whey proteins or their hydrolysates, this study proposed a method that involved limited enzymatic hydrolysis followed by the addition of EGCG and pH adjustment around the isoelectric point to obtain whey protein hydrolysates (WPH)-EGCG. Over 92 % of protein-EGCG complexes recovered from whey while ensuring the preservation of α-lactalbumin. The combination between EGCG and WPH depended on hydrogen bonding and hydrophobic interactions, significantly enhanced the thermal stability and storage stability of EGCG. Besides, the intestinal phase retention rate of EGCG in WPH-EGCG complex was significantly increased by 23.67 % compared to free EGCG. This work represents an exploratory endeavor in the improvement of EGCG stability and expanding the utilization approaches of whey.

Angiotensin-Converting Enzyme and Renin-Inhibitory Activities of Protein Hydrolysates Produced by Alcalase Hydrolysis of Peanut Protein

Hypertension is a major controllable risk factor associated with cardiovascular disease (CVD) and overall mortality worldwide. Most people with hypertension must take medications that are effective in blood pressure management but cause many side effects. Thus, it is important to explore safer antihypertensive alternatives to regulate blood pressure. In this study, peanut protein concentrate (PPC) was hydrolyzed with 3-5% Alcalase for 3-10 h. The in vitro angiotensin-converting enzyme (ACE) and renin-inhibitory activities of the resulting peanut protein hydrolysate (PPH) samples and their fractions of different molecular weight ranges were determined as two measures of their antihypertensive potentials. The results show that the crude PPH produced at 4% Alcalase for 6 h of hydrolysis had the highest ACE-inhibitory activity with IC50 being 5.45 mg/mL. The PPH samples produced with 3-5% Alcalase hydrolysis for 6-8 h also displayed substantial renin-inhibitory activities, which is a great advantage over the animal protein-derived bioactive peptides or hydrolysate. Remarkably higher ACE- and renin-inhibitory activities were observed in fractions smaller than 5 kDa with IC50 being 0.85 and 1.78 mg/mL. Hence, the PPH and its small molecular fraction produced under proper Alcalase hydrolysis conditions have great potential to serve as a cost-effective anti-hypertensive ingredient for blood pressure management.

Alcalase-hydrolyzed insoluble soybean meal hydrolysate aggregates: Structure, bioactivity, function properties, and influences on the stability of oil-in-water emulsions

We studied the influences of hydrolysis time on the structure, functional properties, and emulsion stability of insoluble soybean meal hydrolysate aggregates (ISMHAs). We assume that the ISMHAs produced by soybean meal can be used as emulsifiers to prepare stable emulsions. The molecular weights of these ISMHAs were below 53 kDa. After hydrolysis, a decrease in α-helices and an increase in random coils indicated that the soybean meal proteins were unfolding. Moreover, the fluorescence intensity, UV absorption, and surface hydrophobicity of ISMHAs increased. These results would contribute to their antioxidant activity and functional properties. Additionally, the 90-min ISMHA sample exhibited the highest ABTS+• scavenging activity (80.02 ± 4.55 %), foaming stability (52.92 ± 8.06 %), and emulsifying properties (emulsifying activity index of 97.09 m2/g; emulsifying stability index of 371.47 min). The 90-min ISMHA emulsion exhibited the smallest particle size and excellent storage stability. Soybean meal peptide by-product emulsifier has potential for sustainable application.

Fabrication of diosmin loaded food-grade bilayer nanoparticles with modified chitosan and soy peptides and antioxidant properties examination

Diosmin is a flavonoid derived from plants, possessing anti-inflammatory, antioxidant, antidiabetic, neuroprotective and cardiovascular protective properties. However, diosmin has low solubility in water, leading to low bioavailability. In this study, we constructed bilayer nanoparticles with trimethyl chitosan and soy peptides to improve the oral bioaccessibility and bioavailability of diosmin, and determined the characteristics and antioxidant properties of the diosmin-loaded nanoparticles. The results showed that the size of the nanoparticles was around 250 nm with the encapsulation efficiency higher than 97 %, and the nanoparticles were stable under regular conditions. In vitro digestion suggested the nanoparticles could protect diosmin from releasing in gastric digestion but promote the bioaccessibility of diosmin in intestine. Furthermore, the diosmin-loaded nanoparticles presented excellent antioxidant activities in vitro and significantly decreased the Lipopolysaccharides-induced brain Malondialdehyde (MDA) level by oral administration. Therefore, the reported nanoparticles may be an effective platform for improving the oral bioavailability of diosmin.

Gastrointestinal delivery of codfish Skin-Derived collagen Hydrolysates: Deep eutectic solvent extraction and bioactivity analysis

The fishing industry produces substantial by-products, such as heads, skins, bones, and scales, rich in collagen-a prevalent protein in these materials. However, further application of deep eutectic solvent-based extraction remains unexplored. In this study, we extracted collagen with urea: propanoic acid mixture (U:PA; 1:2) with a 2.2 % yield, followed by enzymatic hydrolysis with alcalase for 120 min. The resulting bioactive peptides demonstrated notable antioxidant activity (961 µmol TE) and antihypertensive properties (39.3 % ACE inhibition). Subsequently, we encapsulated 39.3 % of these hydrolysates in chitosan-TPP capsules, which released about 58 % of their content, primarily in the intestine, as mimicked in the in vitro model of the gastrointestinal tract. Although the digestion process did not significantly alter the size of the non-encapsulated collagen peptides, it did influence their health benefits. The promising results suggest that further research could optimize the use of collagen from fish by-products, potentially offering a sustainable source for health products.

Synergistic Hydrolysis of Soy Proteins Using Immobilized Proteases: Assessing Peptide Profiles

Because of the health benefits and economic opportunities, extracting bioactive peptides from plant proteins, often food processing by-products, garners significant interest. However, the high enzyme costs and the emergence of bitter peptides have posed significant challenges in production. This study achieved the immobilization of Alcalase and Flavorzyme using cost-effective SiO2 microparticles. Mussel-inspired chemistry and biocompatible polymers were employed, with genipin replacing glutaraldehyde for safer crosslinking. This approach yielded an enzyme loading capacity of approximately 25 mg/g support, with specific activity levels reaching around 180 U/mg for immobilized Alcalase (IA) and 35 U/mg for immobilized Flavorzyme (IF). These immobilized proteases exhibited improved activity and stability across a broader pH and temperature range. During the hydrolysis of soy proteins, the use of immobilized proteases avoided the thermal inactivation step, resulting in fewer peptide aggregates. Moreover, this study applied peptidomics and bioinformatics to profile peptides in each hydrolysate and identify bioactive ones. Cascade hydrolysis with IA and IF reduced the presence of bitter peptides by approximately 20%. Additionally, 50% of the identified peptides were predicted to have bioactive properties after in silico digestion simulation. This work offers a cost-effective way of generating bioactive peptides from soy proteins with reducing potential bitterness.

Effects of enzymatic modification on the stability of cashew-based milk

The green and low-carbon awareness drives the consumption demand for "clean-label" plant-based milk, which is limited by its physicochemical stability. Herein, the effects of enzymatic hydrolysis on the stability of cashew-based milk (CM) are explored in detail. Our results showed that a maximum protein solubility of 41.36 ± 2.14% was achieved under bromelain treatment of CM either for 60 min or with the addition of 600 U g-1. Under these hydrolysis conditions, CM showed smaller particle size, larger zeta potential, and more uniform size distribution in comparison with the control. Similar behavior was also observed in the apparent viscosity and macroscopic stability, demonstrating the fortification of moderate hydrolysis on the physical stability of CM. Interestingly, bromelain hydrolysis could favor improving the oxidative stability of CM, for which the peroxide value and thiobarbituric acid reactive substances were decreased by 90% and 60%, respectively, after 14 days of storage in comparison with the control. The correlation analysis confirmed that the physical and oxidative stability was highly associated with protein solubility and secondary structures like α-helix. Therefore, our findings could provide scientific support for developing plant-based milk with fortified physicochemical stability.

Possible role of polypeptide-chlorogenic acid interaction in the physicochemical and sensory characteristics of quinoa-modified coffee beverage

The effect of quinoa protein hydrolysate (QPH) beverage on the physicochemical and sensory characteristics of coffee was investigated. The scores of sensory properties of coffee-quinoa beverage revealed that the unpleasant sensory characteristics, such as extreme bitterness and astringency, were covered up by the addition of quinoa beverage; while smooth mouthfeel and sweetness were enhanced. On the other hand, the introduction of coffee into quinoa beverage significantly retarded oxidation characterized by TBARS. When treated with chlorogenic acid (CGA), significant structural changes and improved functionalities of QPH were detected. CGA induced the unfolding structure of QPH and decreased surface hydrophobicity. The interaction between QPH and CGA was shown by the changes of sulfydryl content and the pattern of SDS-PAGE. Besides, neutral protease treatment increased the equilibrium oil-water interfacial pressure value of QPH, revealing improved stability of emulsions. Synergistic antioxidant effect between QPH and CGA was revealed by increased ABTS^+· scavenging rate.

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.

The Beneficial Effects of Soybean Proteins and Peptides on Chronic Diseases

With lifestyle changes, chronic diseases have become a public health problem worldwide, causing a huge burden on the global economy. Risk factors associated with chronic diseases mainly include abdominal obesity, insulin resistance, hypertension, dyslipidemia, elevated triglycerides, cancer, and other characteristics. Plant-sourced proteins have received more and more attention in the treatment and prevention of chronic diseases in recent years. Soybean is a low-cost, high-quality protein resource that contains 40% protein. Soybean peptides have been widely studied in the regulation of chronic diseases. In this review, the structure, function, absorption, and metabolism of soybean peptides are introduced briefly. The regulatory effects of soybean peptides on a few main chronic diseases were also reviewed, including obesity, diabetes mellitus, cardiovascular diseases (CVD), and cancer. We also addressed the shortcomings of functional research on soybean proteins and peptides in chronic diseases and the possible directions in the future.

Enzymatic hydrolysis of soy and chickpea protein with Alcalase and Flavourzyme and formation of hydrogen bond mediated insoluble aggregates

Food applications involving plant proteins require modification of their functionality to mimic the unique properties of animal proteins. Enzymatic hydrolysis is commonly used to alter the functionality of plant proteins, particularly to improve their solubility near the isoelectric point. Current methodological approaches mostly indicate improved solubility upon hydrolysis. However, published methods include the removal of insoluble material before analysis, and calculations are based on only the solubilized material as a percentage of the filtered protein. This approach artificially increases solubility estimation and gives an incorrect assessment of the efficacy of hydrolysis. By using the total amount of protein, this study aims to determine the effect of two microbial proteases, Flavourzyme and Alcalase, on the solubility and structural and thermal properties of soy and chickpea proteins. Protein isolates were first extracted from soy and chickpea flour and hydrolyzed from 0 to 3 h. Then, their degree of hydrolysis and solubility at a range of pHs were determined using the o-phthaldialdehyde (OPA) and Lowry methods, respectively. Proteins' electrophoretic mobility, protein-protein interactions, thermal properties, and protein secondary structures were also determined. Solubility decreased over time though the solubility of the hydrolysate improved near the isoelectric point. Soy Flavourzyme hydrolysates remained the most soluble and chickpea Flavourzyme hydrolysates showed the least solubility. Thermal data suggested that Alcalase reduced the protein denaturation temperature, leading to a loss of solubility upon thermal enzyme inactivation. The loss of solubility of hydrolysates was strongly associated with hydrogen bonding, which may result from the formation of polar peptide termini. These results challenge commonly accepted beliefs that hydrolysis inevitably improves solubility of plant proteins. Instead, it is shown that hydrolysis causes structural changes that result in aggregation, thus potentially limiting the application of enzymatic hydrolysis without the addition of further processing methods.

Bibliometric Analysis of Functional Crops and Nutritional Quality: Identification of Gene Resources to Improve Crop Nutritional Quality through Gene Editing Technology

Food security and hidden hunger are two worldwide serious and complex challenges nowadays. As one of the newly emerged technologies, gene editing technology and its application to crop improvement offers the possibility to relieve the pressure of food security and nutrient needs. In this paper, we analyzed the research status of quality improvement based on gene editing using four major crops, including rice, soybean, maize, and wheat, through a bibliometric analysis. The research hotspots now focus on the regulatory network of related traits, quite different from the technical improvements to gene editing in the early stage, while the trends in deregulation in gene-edited crops have accelerated related research. Then, we mined quality-related genes that can be edited to develop functional crops, including 16 genes related to starch, 15 to lipids, 14 to proteins, and 15 to other functional components. These findings will provide useful reference information and gene resources for the improvement of functional crops and nutritional quality based on gene editing technology.

Enzymatic hydrolysis of lentil protein concentrate for modification of physicochemical and techno-functional properties

The effects of hydrolysis by commercial food-grade proteases on the physicochemical and techno-functional properties of lentil protein concentrate were investigated. Lentil protein concentrate was hydrolysed with Alcalase, Novozym 11028 or Flavourzyme, and a control was prepared without enzyme addition under the same conditions. Differences in specificity between the three proteases were evident in the electrophoretic protein profile, reversed-phase HPLC peptide profile, and free amino acid composition. Alcalase and Novozym were capable of extensively degrading all the major protein fractions. Alcalase or Novozym treatment resulted in considerably higher solubility under acidic conditions compared to the control. Flavourzyme treatment resulted in moderately improved solubility in the acidic range, but slightly lower solubility at pH 7. Alcalase treatment resulted in slightly larger particle size and slightly higher viscosity. The foaming properties of the protein concentrate were not significantly affected by hydrolysis. Increased solubility in acidic conditions with hydrolysis could broaden the range of food and beverage applications for lentil protein concentrate.

Relationship between flexibility and interfacial functional properties of soy protein isolate: succinylation modification

BACKGROUND

In this paper, the effects of different succinic anhydride (SA) additions on the flexibility of soy protein isolate (SPI) were investigated, and changes in protein conformation and interfacial functional properties were measured. The structure-effect relationship between conformation, flexibility, and interfacial functional properties was established.

RESULTS

SPI was bound to SA through disulfide bonds, and the zeta potential was reduced. The β-sheet content decreased, the disordered structure increased, and there were changes in tertiary structure and microstructure. The surface hydrophobicity, disulfide bond content, and solution turbidity were reduced to 5063, 1.0967 μmol g-1 , and 0.0036 μmol g-1 respectively. The best flexibility of SPI (0.3977) and interfacial functional properties were obtained when the mass ratio of SA/SPI was 15%. Correlation analysis showed a highly significant positive correlation (P < 0.01) between flexibility and emulsification and foaming properties, with correlation coefficients of 0.960 and 0.942 for flexibility with emulsifying activity and emulsion stability respectively, and 0.972 and 0.929 for flexibility with foaming capacity and foaming stability respectively.

CONCLUSION

The results suggest that succinylation-induced conformational changes of SPI improved its interfacial functional properties by changing its flexibility. These results provide theoretical guidelines for the development and application of highly emulsifiable and stable soy protein products utilizing succinylation. © 2022 Society of Chemical Industry.

Formation and stability of Pickering emulsion gels by insoluble soy peptide aggregates through hydrophobic modification

In this work, a highly stable food-grade Pickering emulsion gels was successfully prepared by hydrophobically modified insoluble soybean peptide aggregates. The relationships between the surface properties of insoluble soybean peptide aggregates and Pickering emulsion gels characteristics were clarified. After modification, the insoluble soybean peptide aggregates with high surface hydrophobicity had small particle size (377 nm), near-neutral wettability (θo/w = 92°) and strong interfacial adsorption capability. These allowed the modified insoluble soybean peptide aggregates to stabilize the oil-water interface and form continuous network surrounding oil droplets, leading to the formation of stable Pickering emulsion gels. Besides, Pickering emulsion gels prepared by insoluble soybean peptide aggregates with higher surface hydrophobicity had smaller droplet size and higher gel strength, and remained stable even after 60 days of storage. The findings suggest a preferable plant protein particle for the preparation of stable Pickering emulsion gels in food industry.

Comprehensive Identification of Short and Medium-Sized Peptides from Pixian Broad Bean Paste Protein Hydrolysates Using UPLC-Q-TOF-MS and UHPLC-Q Exactive HF-X

Pixian broad bean paste (PBBP) is an indispensable food widely used in many East Asian countries, yet the knowledge about bioactive peptides released from parent proteins by enzymatic hydrolysis is limited. A total of 5867 low-molecular weight peptides were identified in the highly bioactive subfractions of the PBBP alcalase hydrolysates using traditional and peptidomics approaches. 19 short peptides (3-5 amino acids) were identified by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry, including 5 tripeptides, 8 tetrapeptides, and 6 pentapeptides. 5848 medium-sized peptides (6-10 amino acids) were characterized using the peptidomics approach, including 1484 hexapeptides, 1217 heptapeptides, 1634 octapeptides, 927 nonapeptides, and 586 decapeptides. The comprehensive method can be used for the investigation of bioactive peptides in complex food matrices.

Protein Hydrolysates Derived from Animals and Plants—A Review of Production Methods and Antioxidant Activity

There is currently considerable interest on the use of animal, plant, and fungal sources in the production of bioactive peptides, as evidenced by the substantial body of research on the topic. Such sources provide cheap and environmentally friendly material as it often includes waste and by-products. Enzymatic hydrolysis is considered an efficient method of obtaining peptides capable of antioxidant activity. Those properties have been proven in terms of radical-scavenging capacity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2,2-azinobis-(3-ethyl-benzothiazoline-6-sulphonic acid)), hydroxyl and superoxide radical methods. Additionally, the reducing power, ferrous ion-chelating (FIC), ferric reducing antioxidant power (FRAP), and the ability of the protein hydrolysates to inhibit lipid peroxidation have also been explored. The results collected in this review clearly indicate that the substrate properties, as well as the conditions under which the hydrolysis reaction is carried out, affect the final antioxidant potential of the obtained peptides. This is mainly due to the structural properties of the obtained compounds such as size or amino acid sequences.

Pulse protein processing: The effect of processing choices and enzymatic hydrolysis on ingredient functionality

Plant-based protein ingredients are an emerging solution to the environmental and health issues associated with animal-based proteins. Pulses have become a promising source of these plant-based ingredients. In order to produce functional proteins from pulse grains, extensive processing must be conducted to extract their proteins. These processing steps have consequential effects on the composition and structure of the resulting proteins which may modify their functional properties. This study reviews the most prominent options for each unit operation of pulse protein processing such as extraction, isolation, and drying. It also emphasizes the benefits and drawbacks of such methods and their effects on the pulse protein functionality. Furthermore, enzymatic hydrolysis is discussed as an optional processing step that is thought to counteract loss of functionality associated with pulse protein isolation. However, review of enzymatic hydrolysis literature reveals methodological issues in which insoluble and nonfunctional fractions of pulse protein hydrolysates are removed before analysis. This literature may draw into question the validity of the conventional wisdom that enzymatic hydrolysis is always beneficial to protein functionality.

Characterization of the structure, stability, and activity of hypoglycemic peptides from Moringa oleifera seed protein hydrolysates

Moringa oleifera seed protein hydrolysates exhibit good hypoglycemic activity, but their specific peptide components have not yet been characterized. Here, we identified the ultrafiltration peptide components (<3 kDa) of M. oleifera seed protein hydrolysates. A highly active α-glucosidase inhibitory peptide with an IC₅₀ value of 109.65 μM (MoHpP-2) with the amino acid sequence KETTTIVR was identified. We characterized its structural properties, stability, and hypoglycemic activity. MoHpP-2 was found to be an amphipathic peptide with a β-turn structure, and the hemolysis of red blood cells was not observed when its concentration was lower than 2 mg mL^-1. MoHpP-2 was stable under weakly acidic conditions, at temperatures lower than 60 °C, and at high ion concentrations. Western blotting revealed that MoHpP-2 affected the PI3K and AMPK pathways of HepG2 cells. Molecular docking revealed that MoHpP-2 interacted with α-glucosidase through hydrogen bonding and hydrophobic forces. Thus, MoHpP-2 from M. oleifera seeds could be used to make hypoglycemic functional foods.

Ultrasonic Assisted Extraction of Quinoa (Chenopodium quinoa Willd.) Protein and Effect of Heat Treatment on Its In Vitro Digestion Characteristics

To extract and utilise the protein in quinoa efficiently, we investigated the effect of rate of quinoa protein isolate (QPI) extraction by ultrasound-assisted alkaline extraction and traditional alkaline extraction methods using single-factor experiments and Box-Behnken design. The effect of different heat treatment temperature and time on QPI functional properties and in vitro digestion characteristics were also investigated. The results showed that the optimal conditions of ultrasound- assisted alkaline extraction process were: ultrasonic time 99 min, solid-liquid ratio 1:20 w:v, ultrasonic temperature 47 °C, and pH 10, and its extraction rate and purity were 74.67 ± 1.08% and 87.17 ± 0.58%, respectively. It was 10.18% and 5.49% higher than that of the alkali-soluble acid precipitation method, respectively. The isoelectric point (pI) of QPI obtained by this method was 4.5. The flexibility and turbidity of QPI had maximum values at 90 °C, 30 min, and 121 °C, 30 min, which were 0.42 and 0.94, respectively. In addition, heat treatment changed the 1.77–2.79 ppm protein characteristic region in QPI’s nuclear magnetic resonance hydrogen spectroscopy (¹H NMR). After heating at 90 °C and 121 °C for 30 min, the hydrolysis degree and total amino acid content at the end of digestion (121 °C, 30 min) were significantly lower than those of untreated QPI by 20.64% and 27.85%. Our study provides basic data for the efficient extraction and utilisation of QPI.

Encapsulation of phenolic compounds within food-grade carriers and delivery systems by pH-driven method: a systematic review

In comparison to conventional encapsulation methods of phenolic compounds (PCs), pH-driven method is green, simple and requires low energy consumption. It has a huge potential for industrial applications, and can overcome more effectively the aqueous solubility, stability and bioavailability issues related to PCs by changing pH to induce the encapsulation of PCs. This review aims to shed light on the use of pH-driven method for encapsulating PCs. The preparation steps and principles governing pH-driven method using various carriers and delivery systems are provided. A comparison of pH-driven with other methods is also presented. To circumvent the drawbacks of pH-driven method, improvement strategies are proposed. The essence of pH-driven method relies simultaneously on alkalization and acidification to bind PCs and carriers. It is used for the development of nanoemulsions, liposomes, edible films, nanoparticles, nanogels and functional foods. As a result of pH-driven method, PCs-loaded carriers may have smaller size, high encapsulation efficiency, more sustained-release and good bioavailability, due mainly to effects of pH change on the structure and properties of PCs as well as carriers. Finally, modification of wall materials and type of acidifier are considered as efficient approaches to improve the pH-driven method.

Nano-architectural assembly of soy proteins: A promising strategy to fabricate nutraceutical nanovehicles

Use of protein-based nanovehicles has been well recognized to be one of the most effective strategies to improve water dispersibility, stability and bioavailability of nutraceuticals or bioactive ingredients. Thanks to their health-benefiting effects and unique assembly behavior, soy proteins seem to be the perfect food proteins for fabricating nanovehicles in this regard. This review presents the state-of-art knowledge about the assembly of soy proteins into nano-architectures, e. g., nanoparticles, nanocomplexes or nanogels, induced by different physicochemical strategies and approaches. The strategies to trigger the assembly of soy proteins into a variety of nano-architectures are highlighted and critically reviewed. Such strategies include heating, enzymatic hydrolysis, pH shift, urea or ethanol treatment, reduction, and static high pressure treatment. The self-assembly behavior of soy proteins (native or denatured) is also reviewed. Besides the assembly of proteins alone, soy proteins can co-assemble with polysaccharides to form versatile nano-architectures, through different processes, e.g., heating or ultrasonication. Finally, recent progress in the development of assembled soy protein nano-architectures as nanovehicles for hydrophobic nutraceuticals is briefly summarized. With the fast increasing health awareness for natural and safe functional foods, this review is of crucial relevance for providing an important strategy to develop a kind of novel soy protein-based functional foods with dual-function health effects from soy proteins and nutraceuticals.

Allergenicity, antioxidant activity and ACE-inhibitory activity of protease hydrolyzed peanut flour

Regularly consuming peanuts has been reported to have many health benefits. Peanut flour, a by-product of peanut oil processing, has higher protein and dietary fiber contents than peanut kernels, but its application as protein source in foods and dietary supplement is limited due to the fear of peanut allergy. This study indicates that hydrolysis of peanut flour (12% lipid) up to 4 h with Alcalase lowered the immunoreactivity of both soluble and insoluble portions of peanut flour, generated peanut flour hydrolysate (PFH) with good in vitro antioxidant and ACE-inhibitory activities. Importantly, the fraction smaller than 5 kDa did not bind IgE of peanut allergic patients, but exhibited higher ACE-inhibitory activity than the crude PFH. Thus, peanut flour could be an inexpensive protein source of antioxidant and anti-hypertensive ingredient. These findings are important for the value added application of peanut flour. However, studies with food and animal/human models are needed to confirm the benefits.

pH-Driven formation of soy peptide nanoparticles from insoluble peptide aggregates and their application for hydrophobic active cargo delivery

The insoluble soy peptide aggregates formed upon proteolysis are generally considered as "ready to be discarded", which placed additional burden on related industries. In this study, with the aim of promoting sustainable utilization of these large aggregates, novel soy peptide-based nanoparticles (SPN) were successfully fabricated from these aggregates via a controlled pH-shifting method, and the obtained SPN exhibited good storage stability and antioxidant activity. Furthermore, the pH-shifting process also provided a driven force for loading and delivering curcumin, which significantly improved its water solubility (up to 10⁵ folds), storage and simulated gastric-intestinal digestive stability, as well as in vitro bioavailability and antioxidant activity. These results indicated that controlled pH-shifting could be an effective and facile method to trigger the assembly of insoluble aggregates into functional peptide nanoparticles for the delivery of bioactive cargoes, which provided a new strategy for the sustainable and high-value application of these low-value peptide byproducts.

Rice peptide nanoparticle as a bifunctional food-grade Pickering stabilizer prepared by ultrasonication: Structural characteristics, antioxidant activity, and emulsifying properties

In this study, a novel food-grade Pickering stabilizer was fabricated from insoluble rice peptide aggregates that are considered undesirable and formed during the hydrolysis of rice protein using ultrasonication. The results confirmed that ultrasonication was effective in fabricating rice peptide nanoparticles (RPNs) with a spherical appearance, and the particle size was reduced with ultrasonic time, reaching a minimum size of 357.8 nm in 30 min. Moreover, ultrasonic treatment could improve the antioxidant activity of RPNs by promoting the DPPH scavenging (3.5-fold increase) and Fe²⁺ chelating activity (3.8-fold increase). Notably, the bioactive RPNs could form stable Pickering emulsions that possess both physical and oxidative stability during storage, which might be due to the antioxidative physical barrier formed by RPNs. These findings suggest a new approach for the effective utilization of insoluble aggregates produced during protein hydrolysis as well as provide a novel bifunctional Pickering stabilizer with intrinsic antioxidant properties.

Ultrasound driven conformational and physicochemical changes of soy protein hydrolysates

The effect of ultrasound on the conformational and physicochemical properties of soy protein isolate hydrolysates (SPHs) was investigated. SPHs were prepared at hydrolysis times of 20 min, 60 min, and 180 min, then treated with ultrasound for 10 min, 20 min, and 30 min at a frequency of 20 kHz and output powers of 150 W and 450 W. The structural properties and antioxidant capacities of the aqueous layer of SPHs (ASPHs) after sonication were evaluated by Fourier-transform infrared spectroscopy (FTIR), intrinsic fluorescence, DPPH radical scavenging activity assays, and microscopy observations. Results obtained showed that ultrasound treatment significantly disrupted the peptide aggregates formed during protein hydrolysis. The protein solubility was significantly increased after sonication (by up to 18.33%), as did the percentage of proteins with MW < 1 kDa in ASPHs. The antioxidant capacity of ASPHs also increased, as measured by DPPH assay. FTIR analysis of ASPHs indicated that the protein secondary structures were different, with an increase in β-sheet and a decrease in α-helix and β-turn. Furthermore, the changes in fluorescence spectra of ASPHs showed the transition of protein tertiary structure with a greater exposure of Trp residues in the side chains. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations of the morphological structure of ASPHs further confirmed the significant effect of sonication on disrupting peptide aggregates. In conclusion, ultrasound can be used as an efficient treatment to promote the solubility of protein hydrolysates.

Preparation of bioactive peptides with antidiabetic, antihypertensive, and antioxidant activities and identification of α-glucosidase inhibitory peptides from soy protein

In this study, the peptides of soy protein obtained by enzymatic digestion with proteases were analyzed for their antidiabetic, antihypertensive, and antioxidant activities. Peptides prepared with alkaline proteinase (AP) exhibited the highest α-glucosidase inhibitory activity compared with those from papain and trypsin digestion. AP hydrolysates also exhibited dipeptidyl peptidase IV (DPP-IV) inhibitory, angiotensin-converting enzyme (ACE) inhibitory, and antioxidant activities. Gastrointestinal digestion of peptides enhanced α-glucosidase, DPP-IV, and ACE inhibitory activities compared with AP hydrolysates. AP peptides showing highest α-glucosidase inhibitory activity were purified by anion-exchange and size-exclusion chromatography， and identified using tandem MS. We found three novel α-glucosidase inhibitory peptides with sequences LLPLPVLK, SWLRL, and WLRL with IC50 of 237.43 ± 0.52, 182.05 ± 0.74, and 162.29 ± 0.74 μmol/L, respectively. Therefore, peptides hydrolyzed from soy protein are promising natural ingredients for nutraceutical applications assisting in the management of diabetes.

Peptidomics of potato protein hydrolysates: implications of post-translational modifications in food peptide structure and behaviour

Post-translational modifications (PTMs) often occur in proteins and play a regulatory role in protein function. There is an increasing interest in the bioactivity of food protein-derived peptides, but the occurrence of PTMs and their influence on food peptide structure and behaviour remain largely unknown. In this study, the shotgun-based peptidomics strategy was used to identify the occurrence of PTMs in peptides generated from potato protein hydrolysis using digestive proteases. Diverse PTMs were found in the potato peptides, including acetylation of lysine, N-terminal of proteins and peptides, C-terminal amidation, de-amidation of asparagine/glutamine, methylation and trimethylation, methionine oxidation and N-terminal pyro-glutamyl residue formation. The modifications may have been formed naturally or as a result of chemical reactions during isolation and enzymatic processing of the potato proteins. Most of the PTMs were calculated to decrease the isoelectric point and increase molecular hydrophobicity of the peptides, which will influence their bioactivity while also potentially altering their solubility in an aqueous environment. This is the first study to unravel that food-derived peptides can be widely modified by PTMs associated with notable changes in peptide chemical properties. The findings have broader implications on the bioavailability, biomolecular interactions and biological activities of food peptides.

Development of a Sono-Assembled, Bifunctional Soy Peptide Nanoparticle for Cellular Delivery of Hydrophobic Active Cargoes

Soy proteins are prone to aggregate upon proteolysis, hindering their sustainable development in food processing. Here, a continuous work on the large insoluble peptide aggregates was carried out, aiming to develop a new type of soy peptide-based nanoparticle (SPN) for active cargo delivery. Sono-assembled SPN in spherical appearance and core-shell structure maintained by noncovalent interactions was successfully fabricated, exhibiting small particle size (103.95 nm) in a homogeneous distribution state (PDI = 0.18). Curcumin as a model cargo was efficiently encapsulated into SPN upon sonication, showing high water dispersity (129.6 mg/L, 10⁴ higher than its water solubility) and storage stability. Additionally, the pepsin-resistant SPN contributed to the controlled release of curcumin at the intestinal phase and thus significantly improved the bioaccessibility. Encapsulated curcumin was effective in protecting glutamate-induced toxicity in PC12 cells, where the matrix SPN can simultaneously reduce lipid peroxidation and elevate antioxidant enzymes levels, innovatively demonstrating its bifunctionality during cellular delivery.