Analysis of the interaction between cyanidin-3-O-glucoside and casein hydrolysates and its effect on the antioxidant ability of the complexes

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.

Molecular imprinting-based Ru@SiO2-embedded covalent organic frameworks composite for electrochemiluminescence detection of cyanidin-3-O-glucoside

Cyanidin-3-O-glucoside (C3G), a natural antioxidant, plays multiple physiological or pathological roles in maintaining human health; thereby, designing advanced sensors to achieve specific recognition and high-sensitivity detection of C3G is significant. Herein, an imprinted-type electrochemiluminescence (ECL) sensing platform was developed using core-shell Ru@SiO2-CMIPs, which were prepared by covalent organic framework (COF)-based molecularly imprinted polymers (CMIPs) embedded in luminescent Ru@SiO2 cores. The C3G-imprinted COF shell not only helps generate a steady-enhanced ECL signal, but also enables specific recognition of C3G. When C3G is bound to Ru@SiO2-CMIPs with abundant imprinted cavities, resonance energy transfer (RET) behavior is triggered, resulting in a quenched ECL response. The constructed Ru@SiO2-CMIPs nanoprobes exhibit ultra-high sensitivity, absolute specificity, and an ultra-low detection limit (0.15 pg mL-1) for analyzing C3G in food matrices. This study provides a means to construct an efficient and reliable molecular imprinting-based ECL sensor for food analysis.

The Effect of Whey Protein Isolate Hydrolysate on Digestive Properties of Phytosterol

Phytosterol (PS) is a steroid, and its bioavailability can be enhanced by interacting with protein in the C-24 hydroxyl group. The interaction between sterols and amino acid residues in proteins can be enhanced by enzymatic hydrolysis. Phytosterol and whey insulation hydrolysates (WPH1-4) fabricated by the Alcalase enzyme at different enzymatic hydrolysis times were selected as delivery systems to simulate sterol C-24 hydroxyl group interaction with protein. Increasing hydrolysis time can promote the production of β-Lg, which raises the ratio of β-turn in the secondary structure and promotes the formation of interaction between WPH and PS. The correlation coefficient between hydrogen bonds and encapsulation efficiency (EE) and bioaccessibility is 0.91 and 0.88 (P < 0.05), respectively, indicating that hydrogen bonds of two components significantly influenced the combination by concealing the hydrophobic amino acids and some residues, which improved PS EE and bioavailability by 3.03 and 2.84 times after PS was combined with the WPI hydrolysate. These findings are expected to enhance the absorption of PS and other macromolecules by protein enzymatic hydrolysis to broaden their applications for food.

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.

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.

Enhanced stability and bioavailability of mulberry anthocyanins through the development of sodium caseinate-konjac glucomannan nanoparticles

This study was carried out to improve the stability of anthocyanins (ACNs) by developing MA-SC-KGM nanoparticles using a self-assembly method that involved the combination of sodium caseinate (SC) and konjac glucomannan (KGM) with mulberry anthocyanin extract (MA). Atomic force microscopy (AFM) analysis showed SC encapsulated MA successfully. Multispectral techniques demonstrated the presence of hydrogen bonds and hydrophobic interactions in the nanoparticles. MA-SC-KGM ternary mixture improved storage stability, color stability and anthocyanin retention better compared to the MA-SC binary mixture. Notably, MA-SC-KGM nanoparticles significantly inhibited the thermal degradation of ACNs, improved pH stability, and showed stability and a slow-release effect in gastrointestinal digestion experiments. In addition, MA-SC-KGM nanoparticles were effective in scavenging DPPH· and ABTS+ free radicals, with enhanced stability and antioxidant capacity even during the heating process. This study successfully developed a novel MA-SC-KGM protein-polysaccharide composite material that effectively stabilized natural ACNs, expanding the application of ACNs in various industries.

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, characterization and emulsifying properties of myofibrillar protein-chitosan complexes in acidic conditions

Polysaccharides are employed to modify proteins, forming complexes that enhance the functional properties of proteins, such as emulsification and stability. In this study, myofibrillar protein (MP)-chitosan (CS) complexes were formed between CS and MP under acidic conditions (pH 3.0-6.0). Results showed that CS can improve the solubility and emulsifying properties of MP, and the MP-CS complexes at pH 3.0 and 6.0 had better emulsifying properties. Concurrently, the particle size results indicated that better the emulsifying properties of the complex, the smaller the particle size. Consequently, the characteristics of the MP-CS complexes (at pH 3.0 and 6.0) were investigated. Our analysis using Fourier transform infrared spectroscopy revealed that the amide I band of MP was blue-shifted with the addition of CS, signifying a decrease in hydrogen bonding within MP. The endogenous fluorescence spectra showcased that the hydrophobicity surrounding the tryptophan residues in the protein changed, leading to enhanced polarity. Thermogravimetric analysis and differential scanning calorimetry further confirmed that the addition of CS improved the thermal stability of MP. These findings provide valuable insights into the interactions between MP and CS. Furthermore, the MP-CS complex can be leveraged to create a Pickering emulsion system for the efficient delivery of bioactive substances.

Molecular insights on the binding of chlortetracycline to bovine casein and its effect on the thermostability of chlortetracycline

Bovine casein was selected as a model protein to evaluate the impact of food matrix on the thermal degradation of antibiotics. Fluorescence quenching and isothermal titration calorimetry experiments revealed that chlortetracycline (CTC) could spontaneously bind to casein via hydrogen bonding and hydrophobic interactions. The amino acid residues forming the binding pocket were further identified using molecular docking, while saturation transfer difference NMR deciphered that the binding of CTC engages its -N(CH3)2 group. Moreover, the degradation behavior of free CTC versus that bound in casein-CTC complex was compared during thermal treatment. Compared with free CTC, a lower first-order rate constant was observed in the presence of casein. Removal of casein shortened the half-life of CTC by at least 48.1% at low concentrations. Elucidating that the formation of protein-antibiotic complexes alters the amenability of antibiotics to degradative reactions, which could help eliminate residual antibiotics and guarantee the safety of dairy products.

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.

The aggregation of casein micelles induced by Ca2+ during in vitro digestion: effects on the release of loaded anthocyanins

Colloidal calcium phosphate (CCP) confers a modifiable structure to micellar casein (MC), which endows it with potential advantages as a delivery carrier. However, it is difficult to achieve multipattern release of the core material in the intestine with MC as a single wall. In this study, we prepared an anthocyanin-casein-based delivery system utilizing MC with different freezing degrees as the wall material with the objective of achieving the controlled release of anthocyanin as the model core in the intestine. The results showed that freezing could significantly reduce the CCP level up to 50%. Static in vitro simulated digestion with the addition of exogenous Ca2+ showed that the designed delivery system exhibited low anthocyanin release (15%-35%) in the gastric tract. The pattern of release in the intestine depended on the CCP dissociation degree. High and low dissociation degrees corresponded to slow release (from 15% to 65% within 2 h) and burst release (from 35% to 90% within 5 min), respectively. WAXS/SAXS analysis revealed that exogenous serum Ca2+ inherent in simulated gastric fluid and endogenous serum Ca2+ induced by CCP dissociation was synergistically involved in the reconstitution of CCP-mediated nanoclusters and large aggregates. The freezing degree of MC determined the endogenous serum Ca2+ level, which influenced the gastric aggregation behavior of wall MC and ultimately led to a fairly different gastrointestinal release behavior of anthocyanins.

Investigation on the interaction mechanisms for stability of preheated whey protein isolate with anthocyanins from blueberry

Proteins and anthocyanins coexist in complex food systems. This research mainly studied the steady-state protective design and mechanism of the preheated protein against anthocyanins. Multispectral and molecular dynamics are utilized to illustrate the interaction mechanism between preheated whey protein isolate (pre-WPI) and anthocyanins. The pre-WPI could effectively protect the stability of anthocyanins, and the effect was better than that of the natural whey protein isolate (NW). Among them, NW after preheating treatment at 55 °C showed better protection against anthocyanin stability. Fluorescence studies indicated that pre-WPI there existed a solid binding affinity and static quenching for malvidin-3-galactoside (M3G). Multispectral data showed a significant variation in the secondary structure of pre-WPI. Furthermore, molecular dynamics simulation selects AMBER18 as the protein force field, and the results showed that hydrogen bonding participated as an applied force. Compared with NW, pre-WPI could better wrap anthocyanins and avoid damage to the external environment due to tightening of the pockets. Protein protects anthocyanins from degradation, and this protective effect is influenced by the preheating temperature of protein and the structure of protein. On the basis of the above results, it is possible to pinpoint the interaction mechanism between preheated proteins and anthocyanins.

Effect of Medium Chain Triglycerides on the Digestion and Quality Characteristics of Tea Polyphenols-Fortified Cooked Rice

Nowadays, medium chain triglycerides (MCT) with special health benefits have been increasingly applied for fortifying food products. Therefore, the present work aimed to investigate the effects of MCT on traditional tea polyphenols-fortified cooked rice (TP-FCR). It was visualized by DSC, CLSM, XRD, FT-IR, and Raman spectroscopy. The higher content of starch-MCT complexes with an increase in the relative crystallinity and the generation of short-range ordered structures contributed to a more ordered and compact molecular arrangement, which can hinder the action of digestive enzymes on starch. SEM demonstrated that MCT transformed the microstructure of TP-FCR into a denser and firmer character, making it an essential component hindering the accessibility of digestive enzymes to starch granules and slowing the release of tea polyphenols in TP-FCR to attenuate starch digestion. Consequently, the addition of MCT reduced the polyphenol-regulated starch digestibility from 74.28% in cooked white rice to 64.43% in TP-FCR, and further down to 50.82%. Besides, MCT also reduced the adhesiveness and improved the whiteness of TP-FCR. The findings suggested that MCT incorporation could be a potential strategy in cooked rice production to achieve high sensory quality and low glycemic cooked rice.

Interaction between a Commercial Mannoprotein and Cyanidin-3-O-glucoside-4-vinylphenol and Its Stability and Antioxidative Properties as a Novel Functional Pigment

Hydroxyphenyl-pyranoanthocyanins, which are derived from anthocyanins and phenolic acids during the fermentation and aging of red wine, are prone to polymerization and precipitation, which largely limits their application and bioactivity research. In the present study, cyanidin-3-O-glucoside-4-vinylphenol (C3GVP), a hydroxyphenyl-pyranoanthocaynin, was prepared from C3G and p-coumaric acid, and mannoprotein (MP) was employed to improve its stability in various complex solvents by forming a stable anthocyanin-MP complex. We used scanning electron microscopy, ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, and circular dichroism spectroscopy to observe structural changes in C3GVP and MP. The results demonstrated that the intermolecular polymerization of C3GVP was mitigated and the secondary conformation of MP was changed slightly. Fluorescence spectroscopy and molecular docking indicated that C3GVP and MP interacted via hydrogen bonds and hydrophobic interactions. Importantly, the C3GVP-MP complex exhibited better thermal stability and antioxidant capacity than C3G.

LncRNA profiles of Cyanidin-3-O-glucoside ameliorated Zearalenone-induced damage in porcine granulosa cells

Long non-coding RNA (lncRNA), a class of RNA molecules with transcripts longer than 200 nt, is crucial for maintaining animal reproductive function. Zearalenone (ZEN) damaged animal reproduction by targeting ovarian granulosa cells (GCs), especially in pigs. Nonetheless, it is not quite clear that whether Cyanidin-3-O-glucoside (C3G) exert effects on porcine GCs (pGCs) after ZEN exposure by altering lncRNA expression. Here, we sought to gain novel information regarding C3G protect against damages induced by ZEN in pGCs. The pGCs were divided into control (Ctrl), ZEN, ZEN + C3G (Z + C), and C3G groups. Results revealed that C3G effectively increased cell viability and suppressed ZEN-induced apoptosis in pGCs. 87 and 82 differentially expressed lncRNAs (DELs) were identified in ZEN vs. Ctrl and Z + C vs. ZEN group, respectively. Gene Ontology (GO) analysis observed that the DELs were related to cell metabolism and cell-matrix adhesion biological processes. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the DELs were associated with the phosphatidylinositide 3-kinases (PI3K)-protein kinase B (AKT) signaling pathway. In brief, we demonstrated that C3G could shield apoptosis induced by ZEN, which may be connected with the changes of lncRNA expression profiles in pGCs. This study complemented our understanding of the genetic basis and molecular mechanisms by which C3G mitigated the toxicity of ZEN in pGCs.

Resveratrol and beyond: The Effect of Natural Polyphenols on the Cardiovascular System: A Narrative Review

Cardiovascular diseases (CVDs) are among the leading causes of morbidity and mortality worldwide. Unhealthy dietary habits have clearly been shown to contribute to the development of CVDs. Beyond the primary nutrients, a healthy diet is also rich in plant-derived compounds. Natural polyphenols, found in fruits, vegetables, and red wine, have a clear role in improving cardiovascular health. In this review, we strive to summarize the results of the relevant pre-clinical and clinical trials that focused on some of the most important natural polyphenols, such as resveratrol and relevant flavonoids. In addition, we aim to identify their common sources, biosynthesis, and describe their mechanism of action including their regulatory effect on signal transduction pathways. Finally, we provide scientific evidence regarding the cardiovascular benefits of moderate, long-term red wine consumption.

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.

Synergistic modification of collagen structure using ionic liquid and ultrasound to promote the production of DPP-IV inhibitory peptides

BACKGROUND

Dual modification of collagen was performed using ionic liquid (IL) and ultrasound (US) to modulate the activity of collagen hydrolyzed peptides and reveal the production mechanism of cowhide-derived dipeptidyl peptidase (DPP-IV) inhibitory peptides.

RESULTS

The results revealed that dual modification (IL + US) significantly improved the hydrolytic degree of collagen (P < 0.05). Meanwhile, IL and US tended to promote the break of hydrogen bonds, but inhibit the crosslinking between collagens. The double modification reduced the thermal stability and accelerated the exposure of tyrosine and phenylalanine of collagen, and improved the proportion of small molecular (< 1 kDa) peptides in collagen hydrolysates. Interestingly, the hydrophobic amino acid residues and DPP-IV inhibitory activity of collagen peptides with small molecular weight (< 1 kDa) was increased further under the combination of IL and US.

CONCLUSION

Enhanced hypoglycemic activity of collagen peptides can be attained through the dual modification of IL and US. © 2023 Society of Chemical Industry.

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.

Physicochemical and functional properties of capsaicin loaded cricket protein isolate and alginate complexes

As people become more aware of the health benefits of foods and their nutritional benefits for preventing diseases and promoting health, the demand for functional foods rich in proteins, fiber, and bioactives like capsaicin (CAP) is constantly rising. This study hypothesized that the electrostatic complexes developed by cricket protein isolate (CPI) and alginate (AL) could be utilized to encapsulate CAP, making it more water-soluble and protecting it at acidic pHs. Quantitative analysis revealed that CAP was efficiently encapsulated into the CPI-AL complexes with a maximum encapsulation efficiency of 91%, improving its aqueous solubility 45-fold. In vitro release tests showed that CAP was retained at acidic pHs (3.0 and 5.0) in CPI-AL complexes but released steadily at neutral pH (7.4), which will protect CAP in the stomach while enabling its release in the small intestine. Moreover, the antioxidant activity of CAP-CPI-AL complexes was superior to that of their individual bare equivalents. The complexes also demonstrated enhanced emulsifying capabilities and stability at acidic pHs (2.0-5.0) as the CPI fraction in the complexes increased. Our findings thus contribute to the growing body of knowledge that validates protein-polysaccharide complexation as a promising strategy for developing edible delivery systems.

Collagen hydrolysates improve the efficiency of sodium alginate-encapsulated tea polyphenols in beads and the storage stability after commercial sterilization

This study showed that sodium alginates (SA)-based beads reinforced with collagen hydrolysates (CHs) significantly increased an encapsulation rate of tea polyphenols (TP) from 34.54 % to 85.06 % when the mass ratio of SA: CHs increased from1.5:0 to 1.5:0.5. And after the 30-day storage at 37 °C, the retention rate of TP in beads with CHs at the solutions with pH = 4.0 or pH = 7.0 increased from 61.10 % to 80.21 %, or from 67.72 % to 80.47 % after sterilization at 98 °C or 121 °C for 30 min, respectively. Also, the addition of CHs at 0.5 % resulted in a greater retention of the polyphenolic compositions values of TP determined by UPLC-Orbitrap-MS system. Additionally, the DPPH and ABTS⁺ free-radical scavenging capacities and ferric-reducing antioxidant power of beads with CHs after sterilization at 98 °C or 121 °C for 30 min were significantly higher than which without CHs. Physical phenomena based on ζ-potential, particle size, fluorescence, UV spectroscopy and confocal laser scanning microscope showed that tightly non-covalent complexes of CHs in combination to TP could be uniformly and stably distributed in the network of SA solution for encapsulating TP in SA-based beads. These findings provided suggestions for the co-encapsulation design and development of hydrophilic nutritive compounds based on CHs in SA-based beads.

High-Stability Bi-Layer Films Incorporated with Liposomes @Anthocyanin/Carrageenan/Agar for Shrimp Freshness Monitoring

High-stability bi-layer films were prepared by incorporating anthocyanin-loaded liposomes into carrageenan and agar (A-CBAL) for non-destructive shrimp freshness monitoring. The encapsulation efficiency of the anthocyanin-loaded liposomes increased from 36.06% to 46.99% with an increasing ratio of lecithin. The water vapor transmission (WVP) of the A-CBAL films, with a value of 2.32 × 10^-7 g · m^-1 · h^-1 · pa^-1, was lower than that of the film with free anthocyanins (A-CBA). The exudation rate of the A-CBA film reached 100% at pH 7 and pH 9 after 50 min, while the A-CBAL films slowed down to a value lower than 45%. The encapsulation of anthocyanins slightly decreased the ammonia sensitivity. Finally, the bi-layer films with liposomes successfully monitored shrimp freshness with visible color changes to the naked eye. These results indicated that films with anthocyanin-loaded liposomes have potential applications in high-humidity environments.

Effect of Flowering Stages on the Content of Active Ingredients and Antioxidant Capability of Bletilla striata Flowers

Bletilla striata (Thunb.) Reichb.f. is a perennial herb with abundant active ingredients. Previous research mainly focused on its tubers, however, the study on flowers, especially the variation of active ingredient contents at different flowering stages, was rarely seen. This study analyzed the total phenols, flavonoids, polysaccharides, anthocyanins, and cyanidin-3-O-glucoside content of B. striata flowers which were in cultivated in Herb Garden of Zhejiang A&F University and collected in May, 2019, in order to investigate the changes in active ingredients and antioxidant capacity among different flowering stages (bud, initial, and full bloom). Changes in radical scavenging capability of DPPH (1,1-Diphenyl-2-picrylhydrazyl radical), ABTS (2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonate)), and hydroxy were analyzed. Significant differences in active ingredient content of flowers were detected among different flowering stages. The total phenolic content increased continuously during the entire flowering stage. The contents of total flavonoid, total polysaccharide, and cyanidin-3-O-glucoside reached peaks at the initial blooming stage and then fell as the flowering process continued. The antioxidant activity in initial stage was the highest than in any other flowering stages. Therefore, we conclude that the initial blooming stage is the best harvesting stage of B. striata flowers. This study provides a robust basis for the harvest and utilization of B. striata flowers in food, medical, and cosmetic industries.

Enhancing the stability of oil-in-water emulsions by non-covalent interaction between whey protein isolate and hyaluronic acid

This study aimed to investigate the effect of non-covalent interactions between different concentrations (0.1-1.2 %, w/v) of hyaluronic acid (HA) and 3 % (w/v) whey protein isolate (WPI) on the stability of oil-in-water emulsions. Non-covalent interactions between WPI and HA were detected using Fourier-transform infrared spectroscopy. The addition of HA increased the electrostatic repulsion between molecules and reduced the particle size of WPI. Circular dichroism spectroscopy results indicated that the addition of HA caused an increase in β-sheet content and a decrease in α-helix and random coil content in WPI. Moreover, HA increased the emulsion viscosity and strength of the interfacial network structure. Micrographs obtained using confocal laser scanning microscopy indicated that the emulsion with 0.8 % (w/v) HA exhibited good dispersion and homogeneity after storage for 14 d. Complexation with HA significantly altered the rheological and emulsifying properties of WPI, providing an emulsion with excellent stability under heating treatment, freeze-thawing treatment and centrifugation. The results provide a potential for HA application in emulsified foods.

Insights into the interaction of cyclooxygenase and lipoxygenase with natural compound 3,4',5,7-Tetrahydroxyflavone based on multi-spectroscopic and metabolomics

Hypoxia induce right ventricular dysfunction in human heart, but the molecular mechanism remains limited. As known, cyclooxygenases (COX) and lipoxygenases (LOX) play a key role in the cardiovascular system under hypoxia. 3,4',5,7-Tetrahydroxyflavone (THF), which widely exists in a variety of plants and vegetables, is famous for good ability to relieve cardiac injury, but the mechanism remains to be further understood. In this study, we firstly estimated the preventive role of THF against hypoxia-induced right ventricular dysfunction. Metabolomics analysis showed there were differential metabolites involved in above process, which helped us to screen the crucial regulated enzymes of these metabolites. Molecular docking and multi-spectroscopic revealed the molecular mechanism of interaction between THF and COX/LOX. Results suggested that THF bound to COX/LOX through static quenching and these bindings were driven by hydrogen bonds. After binding with THF, the secondary structure of COX/LOX was changed. In general, this study indicated that THF inhibited COX/LOX by spontaneously forming complexes with them.

Cyanidin-3-O-glucoside mediated photodegradation of profenofos in water

Flavonoids can sensitize and quench the photolysis of pesticides such as profenofos in surface water. Profenofos has been frequently detected in surface and underground water. The present study investigated the photolysis of profenofos under various conditions, including natural and artificial light illumination, with and without cyanidin-3-O-glucoside (Cy3G) and in pure and surface water. The degradation half-lives of profenofos in distilled water with 10 equivalents Cy3G of profenofos were 21.7 min, 9.5 h, 12.5 h and 180 h under high-pressure mercury light, UV, Xenon lamp and solar irradiation, respectively, while those without Cy3G were 8.1 min, 6.1 h, 8.2 h and 89.9 h, respectively. The photolysis rate of profenofos under sunlight and artificial light was reduced by 1.5-2.7 times due to Cy3G, compared to the Cy3G-free control. Under sunlight irradiation, the effects of Cy3G on profenofos photolysis were larger than those under high-pressure mercury lamp irradiation. Cy3G also significantly reduced the photolysis rate of profenofos under different pH conditions and in natural water. In addition, Cy3G exhibited a significant capacity of scavenging hydroxyl radicals and quenching ¹O₂ in water. The effect of Cy3G on profenofos photolysis was demonstrated through their interrelations in the natural environment. These findings can help understanding of the effect of flavonoids on profenofos photolysis and are of significance for predicting the degradation kinetics of profenofos and accurately assessing its potential biological impacts.

The immune-enhancing effect and in vitro antioxidant ability of different fractions separated from Colla corii asini

In this study, Colla corii asini (CCA) was fractionated into three fractions with different molecular weights using ultracentrifugation equipment. Components with a molecular weight of >10 kDa in F1 accounted for 81.90%, whereas that in F2 and F3 was 15.63% and 0.94%, respectively. The immunomodulatory activity of CCA fractions was investigated using RAW264.7 cell model and their antioxidant abilities were evaluated by 2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) and ferric-reducing antioxidant power (FRAP) assay. The results indicated that RAW264.7 cells treated with F1 released the highest level of nitric oxide, reactive oxygen species, interleukin-6, and tumor necrosis factor-α. The ABTS and FRAP value of F1 were 65.81% and 29.33 μM TE/L, respectively, which were 22.53%, 128.44% and 43.72%, 132.16% higher than that of F2 and F3, respectively. These results suggested that components with a molecular weight of >10 kDa in CCA had stronger immunomodulatory and antioxidant ability, which would help develop the health food based on CCA. PRACTICAL APPLICATIONS: Colla corii asini (CCA) is a famous protein-based traditional Chinese medicine and nutritional supplement. During the processing of CCA, the molecular weight (MW) of CCA collagen components changed dynamically due to the protein aggregation, degradation, and the Maillard reaction. Some studies have shown that the MW distribution of CCA was not uniform. However, the MW range of CCA components which has strong antioxidant and immunomodulatory activity is still not clear, and few studies have reported the mechanism of CCA's immunomodulatory activity and active ingredients. Therefore, it is important to figure out the characteristics of CCA components with stronger immunomodulatory and antioxidant ability, such as the MW distribution and chemical composition of CCA fractions. And this study will be great for the processing of CCA products which has better biological functions.

Physicochemical Antioxidative and Emulsifying Properties of Soybean Protein Hydrolysates Obtained with Dissimilar Hybrid Nanoflowers

This study investigated the changes in the structure and properties of soybean protein after hydrolysis using two types of hybrid nanoflowers (alcalase@Cu3(PO4)2•3H2O (ACHNs) and dispase@Cu3(PO4)2•3H2O (DCHNs)) and examined the basic properties and oxidative stability of hydrolyzed soybean protein emulsions. The formations of the two hybrid nanoflowers were first determined using a scanning electron microscope, transmission electron microscope, and Fourier infrared spectroscopy. The structure and functional properties of soybean protein treated with hybrid nanoflowers were then characterized. The results indicated that the degree of hydrolysis (DH) of the ACHNs hydrolysates was higher than that of the DCHNs for an identical reaction time. Soybean protein hydrolysates treated with two hybrid nanoflowers showed different fluorescence and circular dichroism spectra. The solubility of the hydrolysates was significantly higher (p < 0.05) than that of the soybean protein (SPI) at all pH values tested (2.0−10.0)*: at the same pH value, the maximum solubility of ACHNs hydrolysates and DCHNs hydrolysates was increased by 46.2% and 42.2%, respectively. In addition, the ACHNs hydrolysates showed the highest antioxidant activity (DPPH IC50 = 0.553 ± 0.009 mg/mL, ABTS IC50 = 0.219 ± 0.019 mg/mL, and Fe2+ chelating activity IC50 = 40.947 ± 3.685 μg/mL). The emulsifying activity index of ACHNs and DCHNs hydrolysates reached its maximum after hydrolysis for 120 min at 61.38 ± 0.025 m2/g and 54.73 ± 0.75 m2/g, respectively. It was concluded that the two hydrolysates have better solubility and antioxidant properties, which provides a theoretical basis for SPI product development. More importantly, the basic properties and oxidative stability of the soybean-protein-hydrolysates oil-in-water emulsions were improved. These results show the importance of proteins hydrolyzed by hybrid nanoflowers as emulsifiers and antioxidants in the food and pharmaceutical industry.

Ultrasonic Enhancement of Aqueous Two-Phase Extraction and Acid Hydrolysis of Flavonoids from Malvaviscus arboreus Cav. Flower for Evaluation of Antioxidant Activity

The ultrasonic-assisted aqueous two-phase extraction (UAATPE) of flavonoid glycosides from Malvaviscus arboreous Cav. flower (MACF) was developed using ethanol/ammonia sulfate systems, followed by the ultrasonic-assisted acid hydrolysis (UAAH) of the top extract with HCl solution. The optimization of UAATPE and UAAH processes was accomplished by single-factor experiments and response surface methodology. As a result, the flavonoid glycosides enriched in the top phase could achieve a maximum yield of 35.9 ± 1.1 mg/g by UAATPE and were completely hydrolyzed by UAAH deglycosylation. The flavonoid glycosides and their hydrolyzates were separated and characterized by high-performance liquid chromatography and ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. Ultrasonic enhancement of the extraction and hydrolysis was explored by comparative study. Furthermore, the in vitro activity of the flavonoid glycosides and the aglycones were comprehensively evaluated by antioxidant activity assays, including ferric-reducing antioxidant power and scavenging DPPH, hydroxyl, and superoxide radicals. All of the IC₅₀ values suggest that the antioxidant activity of flavonoid aglycones was stronger than that of their glucosides and even vitamin C, revealing that the deglycosylated flavonoids from MACF were the more powerful antioxidants. This study provided an effective and eco-friendly strategy for the extraction, separation, and purification of flavonoids from MACF, as well as for the development of the potential flavonoid antioxidants.

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.

Plant flavonoids: Classification, distribution, biosynthesis, and antioxidant activity

Flavonoids are a group of natural polyphenol substances abundant in vegetables, fruits, grains, and tea. As plant secondary metabolites, flavonoids play essential roles in many biological processes and responses to environmental factors in plants. Flavonoids are common in human diets and have antioxidant effects as well as other bioactivities (e.g., antimicrobial and anti-inflammatory properties), which reduce the risk of disease. Flavonoid bioactivity depends on structural substitution patterns in their C6-C3-C6 rings. However, reviews of plant flavonoid distribution and biosynthesis, as well as the health benefits of its bioactivity, remain scarce. Therefore, in the present review, we systematically summarize recent progress in the research of plant flavonoids, focusing on their biosynthesis (pathway and transcription factors) and bioactive mechanisms based on epidemic evidence, in vitro and in vivo research, and bioavailability in the human body. We also discuss future opportunities in flavonoid research, including biotechnology, therapeutic phytoproducts, and dietary flavonoids.

The effects of β-lactoglobulin on cyanidin-3-O-glucoside antioxidant activity and bioaccessibility after heat treatment

The impact of heat treatment at different temperatures on the interaction of β-lactoglobulin (β-Lg) and anthocyanin-3-O-glucoside (C3G) was studied. Heat treatment and the addition of C3G changed the secondary structure of β-Lg with decreasing β-sheets and increasing random coils. Interactions between C3G and β-Lg were mainly via hydrogen bonds and van der Waals forces at 25 °C. The elevated temperature promoted hydrophobic interactions between C3G and β-Lg due to an increase in the hydrophobic groups and amino groups on the surface of β-Lg molecules. The addition of β-Lg to the C3G eliminated heat-induced thermal degradation of C3G. The β-Lg-C3G interactions accompanied with increased particle size and constant zeta potential could increase the antioxidant capacity of C3G approximately by 4% to 10% and protect the colour of C3G from degradation under heat treatment. The C3G bioaccessibility with β-Lg addition increased by 26.08%, 33.45%, 83.09%, 72.27%, and 354.62% compared with C-25, C-60, C-85, C-100, and C-121, respectively. The protective effect of the non-covalent interactions on C3G at high temperatures (85 °C to 121 °C) was significantly stronger than at 25 °C and 60 °C. The application of β-Lg in foodstuffs could enhance the antioxidant activity and bioaccessibility of C3G.

Advances in dietary proteins binding with co-existed anthocyanins in foods: Driving forces, structure-affinity relationship, and functional and nutritional properties

Anthocyanins, which are the labile flavonoid pigments widely distributed in many fruits, vegetables, cereal grains, and flowers, are receiving intensive interest for their potential health benefits. Proteins are important food components from abundant sources and present high binding affinity for small dietary compounds, e.g., anthocyanins. Protein-anthocyanin interactions might occur during food processing, ingestion, digestion, and bioutilization, leading to significant changes in the structure and properties of proteins and anthocyanins. Current knowledge of protein-anthocyanin interactions and their contributions to functions and bioactivities of anthocyanin-containing foods were reviewed. Binding characterization of dietary protein-anthocyanins complexes is outlined. Advances in understanding the structure-affinity relationship of dietary protein-anthocyanin interaction are critically discussed. The associated properties of protein-anthocyanin complexes are considered in an evaluation of functional and nutritional values.

Interaction mechanism between soybean protein isolate and citrus pectin

In this study, citrus pectin (CP) and soybean protein isolate (SPI) were used as raw materials to prepare a complex. The interaction mechanism and structural changes between SPI and CP were deeply studied by fluorescence spectroscopy and Fourier infrared spectroscopy. The results show that CP has a strong quenching effect on SPI's endogenous fluorescence, and with the addition of CP, the endogenous fluorescence intensity of SPI decreased from 13,565.2 to 6067.3. The CP quenching of SPI is static quenching, and the number of combined bits is 1.26. The results of three-dimensional fluorescence spectra showed that the addition of CP reduced the polarity of SPI amino acid residue microenvironment and changed the protein structure. Hydrophobic interaction exists between CP and SPI. The results of three-dimensional fluorescence spectra showed that the addition of CP reduced the polarity of the amino acid residue microenvironment of SPI and changed the protein structure. Fourier transform infrared spectroscopy shows that CP could change the secondary structure of SPI by decreasing the α-helix and β-sheet, increasing β-rotation and irregular curl, destroying the ordered structure of SPI and increasing the polarity of the amino acids exposed to the solution. The microstructure analysis shows that SPI-CP composite system has honeycomb structure and dense pores. From the perspective of reaction thermodynamics, it was found that the addition of CP could improve the thermal stability of SPI and increase the denaturation temperature of SPI from 119.73 to 132.97°C. This study can provide a theoretical basis for the preparation of protein-pectin complexes and provides reference for their application in food grade gels and Pickering emulsions.

Interactions between puerarin/daidzein and micellar casein

Puerarin (PUE) and daidzein (DAI) are polyphenols with extensive biological activities. In the present study, the interactions between PUE/DAI and micellar casein (MC) were investigated, and the physicochemical properties of their complexes were analyzed. The results of fluorescence spectrum analysis and molecular docking revealed that the main interactions between DAI and MC were hydrophobic forces, while that between PUE and MC was hydrogen bonding. The FTIR and XRD analyses confirmed the formation of complexes between MC and PUE/DAI. After binding to PUE/DAI, the size of MC increased. The weight loss rate of MC decreased after complexing with PUE/DAI, but its morphology was not extensively modified. The DPPH radical scavenging capacities of PUE-MC and DAI-MC complexes were higher than those of free PUE/DAI in both water and ethanol. In vitro release experiments showed that the release rate of PUE/DAI was inhibited by MC under simulated intestinal conditions. PRACTICAL APPLICATIONS: The low water solubility and poor bioavailability of PUE and DAI limit their application. Micellar casein has high affinity for PUE and DAI. After encapsulated by micellar casein, the release rates of PUE and DAI were prolonged during simulated intestinal digestion. The results would provide useful information for improving the solubility and bioavailability of PUE and DAI, and broadening the use of them in the food and pharmaceutical industry.

In vitro phenolic bioaccessibility of coffee beverages with milk and soy subjected to thermal treatment and protein-phenolic interactions

The effect of skimmed bovine milk and soy protein on the in vitro bioaccessibility of polyphenols in coffee beverages under thermal treatment (25, 90, and 121 °C) and the protein-phenolic interaction was investigated. Thermal treatment at 90 °C and 121 °C reduced the in vitro bioaccessibility of total and individual phenolic. Skimmed milk and soy protein addition increased the total (by 37.01%-64.21% and 24.74%-47.32%, respectively) and individual phenolic in vitro bioaccessibility (by 4.40%-27.29% and 12.02%-28.61%, respectively) of coffee beverages subjected to thermal treatment at 25, 90 and 121 °C. Compared with soy protein, skimmed milk significantly enhanced the in vitro bioaccessibility of coffee polyphenols, possibly owing to the presence of different types and strengths of noncovalent protein-phenolic interactions. These findings can provide certain theoretical knowledge for optimizing the processing technology and formula of the food industry to help improve the health benefits of milk coffee beverages.