A review on protein–phenolic interactions and associated changes

Interactions of different polyphenols with wheat germ albumin and globulin: Alterations in the conformation and emulsification properties of proteins

In this study, chlorogenic acid (CA), piceatannol (PIC), epigallocatechin-3-gallate (EGCG) and ferulic acid (FA) was selected to explore the influence of polyphenol on the structural properties of wheat germ albumin (WGA) and wheat germ globulin (WGG). The emulsifying properties of the emulsions prepared by WGA-EGCG complex were also evaluated. The results indicated that all polyphenols could significantly enhance the antioxidant capacity of WGA and WGG. In particular, EGCG increased the ratio of random coil in WGA and WGG, resulting in protein unfolding and shifting from an order to disorder structure. In addition, lipid oxidation and protein oxidation of the soybean oil emulsion was significantly slowed down by WGA-EGCG. The stability of the emulsions under various environmental stress and the storage time was significantly improved by WGA-EGCG. These findings can provide a reference for expanding the application of wheat germ protein in food industry.

Quercetin on the properties of rice bran oil body: Focused surface charge, oxidative stability and digestive properties

To further enhance the stability of rice bran oil body (RBOB) emulsions, this study examined the impact of various concentrations of quercetin (QU) on the microstructure, rheological properties, oxidative stability, and digestive properties of RBOB emulsions. The results indicated that by incorporating QU concentration, the particle size of RBOB emulsions could be significantly reduced to 300 nm; QU could improve the surface hydrophobicity, the emulsifying activity index and emulsification stability index of RBOB emulsions of 550, 0.078 m2/g and 50.78 min, respectively; the storage stability of RBOB emulsions was further improved; the higher concentration of QU could delay the oxidation of RBOB emulsions, among which, the 500 μmol/L concentration inhibited the strongest effect of oil oxidation. It also improved the thermal stability of RBOB emulsions. After gastrointestinal digestion, the free fatty acids release rate of RBOB emulsions with QU addition decreased to 14.68%, and RBOB emulsions were slowly hydrolyzed. Therefore, adding QU to RBOB helps to improve its stability and delay digestion.

Intermolecular interactions between malvidin-3-O-glucoside and caffeic acid: Structural and thermodynamic characterization and its effect on real wine color quality

The copigmentation effect between malvidin-3-O-glucoside and caffeic acid was comprehensive inquiry on the model wine solution, theoretical simulation and real wine. Thermodynamic parameters were determined by UV/Visible spectroscopy and Isothermal titration calorimetry (ITC). Theoretical data were obtained employing a dispersion-corrected density functional approach. The effects in real wines were investigated by adding the caffeic acid during different fermentation periods. Results shown that the copigmentation reaction between caffeic acid and malvidin-3-O-glucoside is a spontaneous exothermic reaction driven by hydrogen bonding and dispersions forces. Computations show that the polyhydroxyl sugar moiety and phenolic hydroxyl groups are the key active sites. The addition of caffeic acid in post-alcohol fermentation samples evidences an improving color characteristics in the wine.

Effects of Eleutherine bulbosa extract on the myofibrillar protein oxidation and moisture migration of yak meat under oxidation stress

The influence of Eleutherine bulbosa (EB) extract at various levels (1, 4, 7, 10 or 13 g/kg) on the myofibrillar protein oxidation and moisture migration of yak meat in Fenton oxidation system was investigated. The results showed that inclusion of EB extract in yak meat efficiently inhibited carbonyl formation triggered by hydroxyl radicals. Supplementation of EB extract at 1-10 g/kg manifested more contents of the active sulfhydryl, ε-NH2 groups and α-helix structure, and higher solubility of myofibrillar proteins (MPs), but alleviated the turbidity of MPs. However, adding high level of EB extract (13 g/kg) induced the loss of free amine and α-helix content and resulted in more aggregation of MPs. The SDS-PAGE demonstrated that adding 1-7 g/kg EB extract had an obvious protective effect for myosin heavy chain and actin, whereas 10 or 13 g/kg EB extract led to weakened intensities of protein bands. DSC and LF-NMR analysis revealed that 7 g/kg EB extract had appreciable effects on thermal stabilities of MPs, and improved the hydration of yak meat induced by oxidation, while 13 g/kg EB extract accelerated MP structure destabilization and lowered water retention. Our results suggested that incorporation of low levels of EB extract (1-7 g/kg) effectively retarded the oxidative damage to MPs and EB extract could be a promising natural antioxidant in meat processing.

Preparation of oil-in-water emulsions stabilized by faba bean protein-grape leaf polyphenol conjugates: pH-, salt-, heat-, and freeze-thaw-stability

BACKGROUND

Plant proteins are being increasingly utilized as functional ingredients in foods because of their potential health, sustainability, and environmental benefits. However, their functionality is often worse than the synthetic or animal-derived ingredients they are meant to replace. The functional performance of plant proteins can be improved by conjugating them with polyphenols. In this study, the formation and stability of oil-in-water emulsions prepared using faba bean protein-grape leaf polyphenol (FP-GLP) conjugates as emulsifiers. Initially, FP-GLP conjugates were formed using an ultrasound-assisted alkali treatment. Then, corn oil-in-water emulsions were prepared using high-intensity sonication (60% amplitude, 10 min) and the impacts of conjugate concentration, pH, ionic strength, freezing-thawing, and heating on their physicochemical properties and stability were determined.

RESULTS

Microscopy and light scattering analysis showed that oil-in-water emulsions containing small oil droplets could be formed at conjugate concentrations of 2% and higher. The addition of salt reduced the electrostatic repulsion between the droplets, which increased their susceptibility to aggregation. Indeed, appreciable droplet aggregation was observed at ≥ 50 mmol/L sodium chloride. The freeze-thaw stability of emulsions prepared with protein-polyphenol conjugates was better than those prepared using the proteins alone. In addition, the emulsions stabilized by the conjugates had a higher viscosity than those prepared by proteins alone.

CONCLUSION

This study showed that FP-GLP conjugates are effective plant-based emulsifiers for forming and stabilizing oil-in-water emulsions. Indeed, emulsions formed using these conjugates showed improved resistance to pH changes, heating, freezing, and salt addition. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of the dose of administration, co-antioxidants, food matrix, and digestion-related factors on the in vitro bioaccessibility of rosmarinic acid - A model study

This study aimed to determine the effect of the administration dose, combinations with co-antioxidants (vitamin C, caffeic acid, chlorogenic acid, catechin, rutin), and different food matrices (cooked and lyophilized hen eggs, chicken breast, soybean seeds, potatoes) on the potential bioaccessibility of rosmarinic acid (RA) in simulated digestion conditions, depending on the digestion stage (gastric and intestinal) and the contribution of physicochemical and biochemical digestion factors. The in vitro bioaccessibility of RA depended on the digestion stage and conditions. The physicochemical factors were mainly responsible for the bioaccessibility of RA applied alone. The higher RA doses improved its bioaccessibility, especially at the intestinal stage of digestion. Furthermore, the addition of vitamin C and protein-rich food matrices resulted in enhanced intestinal bioaccessibility of RA. In the future, the knowledge of factors influencing the bioaccessibility of RA can help enhance its favorable biological effects and therapeutic potential.

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

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

Characterization of the covalent binding of cyanidin-3-glucoside to bovine serum albumin and its inhibition mechanism for advanced nonenzymatic glycosylation reactions

Nonenzymatic glycosylation of proteins can generate advanced glycosylation end products, which are closely associated with the pathogenesis of certain chronic physiological diseases and aging. In this study, we characterized the covalent binding of cyanidin-3-glucoside (C3G) to bovine serum albumin (BSA) and investigated the mechanism by which this covalent binding inhibits the nonenzymatic glycosylation of BSA. The results indicated that the covalent interaction between C3G and BSA stabilized the protein's secondary structure. Through liquid chromatography-electrospray ionization tandem mass spectrometry analysis, we identified the covalent binding sites of C3G on BSA as lysine, arginine, asparagine, glutamine, and cysteine residues. This covalent interaction significantly suppressed the nonenzymatic glycosylation of BSA, consequently reducing the formation of nonenzymatic glycosylation products. C3G competitively binds to nonenzymatic glycosylation sites (e.g., lysine and arginine) on BSA, thereby impeding the glycosylation process and preventing the misfolding and structural alterations of BSA induced by fructose. Furthermore, the covalent attachment of C3G to BSA preserves the secondary structure of BSA and hinders subsequent nonenzymatic glycosylation events.

Study on the interaction mechanism between (-)-epigallocatechin-3-gallate and myoglobin: Multi-spectroscopies and molecular simulation

(-)-Epigallocatechin-3-gallate (EGCG) is remarkably efficacious in inhibiting the browning of red meat. We therefore propose a hypothesis that EGCG forms complexes with myoglobin, thereby stabilizing its structure and thus preventing browning. This study investigated the interaction mechanism between EGCG and myoglobin. EGCG induced static quenching of myoglobin. Noncovalent forces, including hydrogen bonds and van der Waals, primarily governing the interactions between myoglobin and EGCG. The interactions primarily disrupted myoglobin's secondary structure, thus significantly reducing surface hydrophobicity by 53% (P < 0.05). The modification augmented the solubility and thermal stability of myoglobin. The radius of gyration (Rg) value fluctuated between 1.47 and 1.54 nm, and the hydroxyl groups in EGCG formed an average of 2.93 hydrogen bonds with myoglobin. Our findings elucidated the formation of stable myoglobin-EGCG complexes and the myoglobin-EGCG interaction, thus confirming our initial hypothesis.

Revealing the mechanism of post-harvest processing on rose quality based on dynamic changes in water content, enzyme activity, volatile and non-volatile metabolites

Existing studies on post-harvest processing of edible roses have mainly focused on processing techniques and physicochemical properties of the final dried products, with limited studies on how changes in metabolites during processing affect the quality of these products. This study investigated changes in water content and status, enzyme activity, phenolic compounds, and volatile and non-volatile compounds during processing and revealed the mechanisms by which post-harvest processing (drying without blanching (WBD) and drying with blanching (BD)) affects the quality of dried roses by establishing their correlations. Results showed that the blanching reduced the relative content of free water and water activity, thus reducing the subsequent drying time and enzyme activity. The BD method caused higher levels of phenolic compounds than the WBD method in terms of gallic acid, ellagic acid, epicatechin, and quercetin. The OPLS-DA analysis identified 6 differential volatiles out of 72 detected volatiles, contributing to the unique aroma of dried roses by activating olfactory receptors through hydrogen bonding and hydrophobic interactions. 58 differential metabolites were screened from 964 non-volatile metabolites. KEGG pathway analysis revealed that the changes in volatile and non-volatile metabolites induced by different processing methods were due to the effect of blanching on glutathione and fatty acid metabolism. These findings provide a comprehensive understanding of how post-harvest processing affects the quality of dried roses.

Structural, physicochemical and digestive properties of non-covalent and covalent complexes of ultrasound treated soybean protein isolate with soybean isoflavone

The non-covalent and covalent complexes of ultrasound treated soybean protein isolate (SPI) and soybean isoflavone (SI) were prepared, and the structure, physicochemical properties and in vitro digestion characteristics of SPI-SI complexes were investigated. Ultrasonic treatment increased the non-covalent and covalent binding degree of SPI with SI, and the 240 W ultrasonic covalent complexes had higher binding efficiency. Appropriate ultrasonic treatment caused more uniform particle size distribution, lower average particle size and higher surface charge, which enhanced the free sulfhydryl groups and surface hydrophobicity, thus improving the stability, solubility and emulsifying properties of complexes. Ultrasonic treatment resulted in more disordered secondary structure, tighter tertiary conformation, higher thermal stability and stronger SPI-SI covalent interactions of complexes. These structural modifications of particles had important effects on the chemical stability and gastrointestinal digestion fate of SI. The ultrasonic covalent complexation had a greater resistance to heat-induced chemical degradation of SI and improved its chemical stability. Furthermore, the 240 W ultrasonic covalent complexes showed lower protein digestibility during digestion, and provided stronger protection for SI, which improved the digestion stability and antioxidant activity. Therefore, appropriate ultrasound promoted SPI-SI interactions to improve the stability and functional properties of complexes, which provided a theoretical basis for the development of new complexes and their applications in functional foods.

Characterization of Olive Oil Phenolic Extracts and Their Effects on the Aggregation of the Alzheimer's Amyloid-β Peptide and Tau

The dietary consumption of extra virgin olive oil (EVOO) is believed to slow the progression of Alzheimer's disease (AD) symptoms. Its protective mechanisms are unclear, but specific EVOO phenolic compounds can individually impede the aggregation of amyloid-β (Aβ) peptides and the microtubule-associated protein tau, two important pathological manifestations of AD. It is unknown, however, whether the numerous and variable phenolic compounds that are consumed in dietary EVOO can collectively alter tau and Aβ aggregation as effectively as the individual compounds. The activity of these complex mixtures against Aβ and tau may be moderated by competition between active and nonactive phenolic components and by extensive derivatizations and isomerization. Here, phenolic mixtures extracted from two different EVOO sources are characterized and tested for how they modulate the aggregation of Aβ40 peptide and tau peptides in vitro. The chromatographic and NMR analysis of Greek and Saudi Arabian EVOO phenolic extracts reveals that they have different concentration profiles, and over 30 compounds are identified. Thioflavin T fluorescence and circular dichroism measurements show that relatively low concentrations (<20 μg/mL) of the Greek and Saudi extracts reduce the rate of Aβ40 aggregation and fibril mass, despite the extracts having different phenolic profiles. By contrast, the Greek extract reduces the rate of tau aggregation only at very high phenolic concentrations (>100 μg/mL). Most compounds in the extracts bind to preformed Aβ40 fibrils and release soluble Aβ oligomers that are mildly toxic to SH-SY5Y cells. Much higher (500 μg/mL) extract concentrations are required to remodel tau filaments into oligomers, and a minimal binding of phenolic compounds to the preformed filaments is observed. It is concluded that EVOO extracts having different phenol profiles are similarly capable of modulating Aβ40 aggregation and fibril morphology in vitro at relatively low concentrations but are less efficient at modulating tau aggregation. Over 2 M tonnes of EVOO are consumed globally each year as part of the Mediterranean diet, and the results here provide motivation for further clinical interrogation of the antiaggregation properties of EVOO as a potential protective mechanism against AD.

Design of Scaffolds Based on Zinc-Modified Marine Collagen and Bilberry Leaves Extract-Loaded Silica Nanoparticles as Wound Dressings

Purpose

In this study, wound dressings were designed using zinc-modified marine collagen porous scaffold as host for wild bilberry (WB) leaves extract immobilized in functionalized mesoporous silica nanoparticles (MSN). These new composites were developed as an alternative to conventional wound dressings. In addition to the antibacterial activity of classic antibiotics, a polyphenolic extract could act as an antioxidant and/or an anti-inflammatory agent as well.

Methods

Wild bilberry leaves extract was prepared by ultrasound-assisted extraction in ethanol and its properties were evaluated by UV-Vis spectroscopy (radical scavenging activity, total amount of polyphenols, flavonoids, anthocyanins, and condensed tannins). The extract components were identified by HPLC, and the antidiabetic properties of the extract were evaluated via α-glucosidase inhibitory activity. Spherical MSN were modified with propionic acid or proline moieties by post-synthesis method and used as carriers for the WB leaves extract. The textural and structural features of functionalized MSN were assessed by nitrogen adsorption/desorption isotherms, small-angle XRD, SEM, TEM, and FTIR spectroscopy. The composite porous scaffolds were prepared by freeze drying of the zinc-modified collagen suspension containing WB extract loaded silica nanoparticles.

Results

The properties of the new composites demonstrated enhanced properties in terms of thermal stability of the zinc-collagen scaffold, without altering the protein conformation, and stimulation of NCTC fibroblasts mobility. The results of the scratch assay showed contributions of both zinc ions from collagen and the polyphenolic extract incorporated in functionalized silica in the wound healing process. The extract encapsulated in functionalized MSN proved enhanced biological activities compared to the extract alone: better inhibition of P. aeruginosa and S. aureus strains, higher biocompatibility on HaCaT keratinocytes, and anti-inflammatory potential demonstrated by reduced IL-1β and TNF-α levels.

Conclusion

The experimental data shows that the novel composites can be used for the development of effective wound dressings.

Multianalytical Approach to Understand Polyphenol-Mal d 1 Interactions to Predict Their Impact on the Allergenic Potential of Apples

Interactions between phenolic compounds and the allergen Mal d 1 are discussed to be the reason for better tolerance of apple cultivars, which are rich in polyphenols. Because Mal d 1 is susceptible to proteolytic digestion and allergenic symptoms are usually restricted to the mouth and throat area, the release of native Mal d 1 during the oral phase is of particular interest. Therefore, we studied the release of Mal d 1 under different in vitro oral digestion conditions and revealed that only 6-15% of the total Mal d 1 present in apples is released. To investigate proposed polyphenol-Mal d 1 interactions, various analytical methods, e.g., isothermal titration calorimetry, 1H-15N-HSQC NMR, and untargeted mass spectrometry, were applied. For monomeric polyphenols, only limited noncovalent interactions were observed, whereas oligomeric polyphenols and browning products caused aggregation. While covalent modifications were not detectable in apple samples, a Michael addition of epicatechin at cysteine 107 in r-Mal d 1.01 was observed.

Simultaneous High-Performance Recovery and Extended Acid-Catalyzed Hydrolysis of Oleuropein and Flavonoid Glycosides of Olive (Olea europaea) Leaves: Hydrothermal versus Ethanol Organosolv Treatment

Olive leaves (OLLs) are an exceptional bioresource of natural polyphenols with proven antioxidant activity, yet the applicability of OLL extracts is constrained by the relatively high polarity of the major polyphenols, which occur as glycosides. To overcome this limitation, OLLs were subjected to both hydrothermal and ethanol organosolv treatments, fostered by acid catalysis to solicit in parallel increased polyphenol recovery and polyphenol modification into simpler, lower-polarity substances. After an initial screening of natural organic acids, oxalic acid (OxAc) was found to be the highest-performing catalyst. The extraction behavior using OxAc-catalyzed hydrothermal and ethanol organosolv treatments was appraised using kinetics, while treatment optimization was accomplished by deploying response-surface methodology. The comparative assessment of the composition extracts produced under optimal conditions of residence time and temperature was performed with liquid chromatography-tandem mass spectrometry and revealed that OLLs treated with 50% ethanol/1.5% HCl suffered extensive oleuropein and flavone glycoside hydrolysis, affording almost 23.4 mg hydroxytyrosol and 2 mg luteolin per g dry weight. On the other hand, hydrothermal treatment with 5% OxAc provided 20.2 and 0.12 mg of hydroxytyrosol and luteolin, respectively. Apigenin was in all cases a minor extract constituent. The study presented herein demonstrated for the first time the usefulness of using a natural, food-grade organic acid to perform such a task, yet further investigation is needed to maximize the desired effect.

The mechanism of resveratrol stabilization and degradation by synergistic interactions between constituent proteins of whey protein

Whey protein isolate (WPI) is mainly composed of β-lactoglobulin (β-LG), α-lactalbumin (α-LA) and bovine serum albumin (BSA). The aim of this study was to compare and analyze the influence of WPI and its three main constituent proteins, as well as proportionally reconstituted WPI (R-WPI) on resveratrol. It was found that the storage stability of resveratrol was protected by WPI, not affected by R-WPI, but reduced by individual whey proteins at 45°C for 30 days. The rank of accelerated degradation of resveratrol by individual whey proteins was BSA > α-LA > β-LG. The antioxidant activity, localization of resveratrol and oxidation of carrier proteins were determined by ABTS, H2O2 assay, synchronous fluorescence, carbonyl and circular dichroism. The non-covalent interactions and disulfide bonds between constituent proteins improved the antioxidant activity of the R-WPI-resveratrol complex, the oxidation stability of the carrier and the solvent shielding effect on resveratrol, which synergistically inhibited the degradation of resveratrol in R-WPI system. The results gave insight into elucidating the interaction mechanism of resveratrol with protein carriers.

Pruned tea biomass plays a significant role in functional food production: A review on characterization and comprehensive utilization of abandon-plucked fresh tea leaves

Tea is the second largest nonalcoholic beverage in the world due to its characteristic flavor and well-known functional properties in vitro and in vivo. Global tea production reaches 6.397 million tons in 2022 and continues to rise. Fresh tea leaves are mainly harvested in spring, whereas thousands of tons are discarded in summer and autumn. Herein, pruned tea biomass refers to abandon-plucked leaves being pruned in the non-plucking period, especially in summer and autumn. At present, no relevant concluding remarks have been made on this undervalued biomass. This review summarizes the seasonal differences of intrinsic metabolites and pays special attention to the most critical bioactive and flavor compounds, including polyphenols, theanine, and caffeine. Additionally, meaningful and profound methods to transform abandon-plucked fresh tea leaves into high-value products are reviewed. In summer and autumn, tea plants accumulate much more phenols than in spring, especially epigallocatechin gallate (galloyl catechin), anthocyanins (catechin derivatives), and proanthocyanidins (polymerized catechins). Vigorous carbon metabolism induced by high light intensity and temperature in summer and autumn also accumulates carbohydrates, such as soluble sugars and cellulose. The characteristics of abandon-plucked tea leaves make them not ideal raw materials for tea, but suitable for novel tea products like beverages and food ingredients using traditional or hybrid technologies such as enzymatic transformation, microbial fermentation, formula screening, and extraction, with the abundant polyphenols in summer and autumn tea serving as prominent flavor and bioactive contributors.

Extraction of Bioactive Compounds from Wine Lees: A Systematic and Bibliometric Review

The extraction of bioactive compounds from wine lees involves a variety of methods, the selection of which is crucial to ensure optimal yields. This systematic review, following PRISMA guidelines and utilizing the Web of Science database, aimed to examine the current state of this field, providing insights for future investigations. The search employed strategies with truncation techniques and Boolean operators, followed by a three-step screening using well-defined eligibility criteria. A bibliometric analysis was conducted to identify authors, affiliations, countries/regions, and research trends. Thirty references were selected for analysis, with Spain standing out as the main source of research on the topic. The majority of studies (66%) focused on the extraction of bioactive compounds from alcoholic fermentation lees, while 33% were directed towards malolactic fermentation lees. Binary mixtures (ethanol-water) were the predominant solvents, with ultrasound being the most used extraction method (31.3%), providing the highest average yields (288.6%) for the various evaluated compounds, especially flavonoids. The potential of wine lees as a source of bioactive compounds is highlighted, along with the need for further research exploring alternative extraction technologies and the combination of methods. Additionally, the importance of "in vitro" and "in vivo" tests to assess the bioactive potential of lees, as well as the use of computational tools to optimize extraction and identify the molecules responsible for bioactive activity, is emphasized.

Protein-Chlorogenic Acid Interactions: Mechanisms, Characteristics, and Potential Food Applications

The interactions between proteins and chlorogenic acid (CGA) have gained significant attention in recent years, not only as a promising approach to modify the structural and techno-functional properties of proteins but also to enhance their bioactive potential in food systems. These interactions can be divided into covalent (chemical or irreversible) and non-covalent (physical or reversible) linkages. Mechanistically, CGA forms covalent bonds with nucleophilic amino acid residues of proteins by alkaline, free radical, and enzymatic approaches, leading to changes in protein structure and functionality, such as solubility, emulsification properties, and antioxidant activity. In addition, the protein-CGA complexes can be obtained by hydrogen bonds, hydrophobic and electrostatic interactions, and van der Waals forces, each offering unique advantages and outcomes. This review highlights the mechanism of these interactions and their importance in modifying the structural, functional, nutritional, and physiological attributes of animal- and plant-based proteins. Moreover, the potential applications of these protein-CGA conjugates/complexes are explored in various food systems, such as beverages, films and coatings, emulsion-based delivery systems, and so on. Overall, this literature review provides an in-depth overview of protein-CGA interactions, offering valuable insights for future research to develop novel protein-based food and non-food products with improved nutritional and functional characteristics.

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

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

Investigating the Formation of In Vitro Immunogenic Gluten Peptides after Covalent Modification of Their Structure with Green Tea Phenolic Compounds under Alkaline Conditions

Celiac disease is an autoimmune disorder triggered by immunogenic gluten peptides produced during gastrointestinal digestion. To prevent the production of immunogenic gluten peptides, the stimulation of covalent-type protein-polyphenol interactions may be promising. In this study, gluten interacted with green tea extract (GTE) at pH 9 to promote the covalent-type gluten-polyphenol interactions, and the number of immunogenic gluten peptides, 19-mer, 26-mer, and 33-mer, was monitored after in vitro digestion. Treatment of gluten with GTE provided an increased antioxidant capacity, decreased amino group content, and increased thermal properties. More importantly, there was a remarkable (up to 73%) elimination of immunogenic gluten peptide release after the treatment of gluten with 2% GTE at 50 °C and pH 9 for 2 h. All of these confirmed that gluten was efficiently modified by GTE polyphenols under the stated conditions. These findings are important in developing new strategies for the development of gluten-free or low-gluten food products with reduced immunogenicity.

Adzuki and Mung Bean Sprouts Enriched with Probiotic Lactiplantibacillus plantarum 299v Improve Body Mass Gain and Antioxidant Status and Reduce the Undesirable Enzymatic Activity of Microbiota in Healthy Rats

Introducing and establishing new food requires a detailed evaluation of its safety, nutritional value and functionality, thus the control and probiotic-rich adzuki and mung bean sprouts were studied in an in vivo rats model. However, the total feed intake did not differ significantly between the groups, the highest body weight gain and body weight change were recorded in the control AIN diet. At the same time, the addition of legume sprouts caused a reduction of these parameters (up to 25% in the variant with probiotic-rich adzuki bean sprouts). There was no significant effect on serum morphology, except white blood cells (ca. 20% reduction in the control sprout-supplemented diets). Serum and liver antiradical properties were significantly elevated by consuming mung bean sprouts (no effect of the probiotics). The faecal lactic acid bacteria were already increased by the control sprouts (a 2.8- and 2.1-fold increase for adzuki and mung bean sprouts, respectively). The probiotic-rich sprouts further improved this parameter. The diets enriched with mung bean sprouts significantly decreased the urease (by ca. 65%) and β-glucuronidase activities (by ca. 30%). All the tested diets caused also a significant reduction of faecal tryptophanase activity (the effect was intensified by Lactiplantibacillus plantarum 299v). The functional components did not affect negatively the nutritional parameters and blood morphological characteristics. They improved also the antioxidant potential and significantly decreased the activities of colon cancer-related enzymes (urease and tryptophanase). The results confirmed that these new probiotic carriers may be a valuable, safe and functional element of a healthy diet.

Non-covalent binding of chlorogenic acid to myofibrillar protein improved its bio-functionality properties and metabolic fate

As natural antioxidants added to meat products, polyphenols can interact with proteins, and the acid-base environment influenced the extent of non-covalent and covalent interactions between them. This study compared the bio-functional characteristics and metabolic outcomes of the myofibrillar protein-chlorogenic acid (MP-CGA) complexes binding in different environments (pH 6.0 and 8.5). The results showed that CGA bound with MP significantly enhanced its antioxidant activity and inhibitory effect on metabolism enzymes. CGA bound deeply into the MP structure hydrophobic cavity at pH 6.0, which reduced its degradation by digestive enzymes, thus increasing its bio-accessibility from 59.5% to 71.6%. The digestion products of the two complexes exhibited significant differences, with the non-covalent MP-CGA complexes formed at pH 6.0 showing significantly higher concentrations of rhetsinine and piplartine, two well-known compounds to modulate diabetes. This study demonstrated that non-covalent binding between protein and polyphenol in the acidic environment held greater promising prospects for improving health.

Effect of the Addition of Dandelion (Taraxacum officinale) on the Protein Profile, Antiradical Activity, and Microbiological Status of Raw-Ripening Pork Sausage

The study evaluated the effect of adding dandelion extract on the characteristics of raw-ripening pork sausages while reducing the nitrite addition from 150 to 80 mg/kg. The sausages were made primarily from pork ham (80%) and pork jowl (20%). The process involved curing, preparing the meat stuffing, forming the links, and then subjecting the sausages to a 21-day ripening period. Physicochemical parameters such as pH, water activity, and oxidation-reduction potential were compared at the beginning of production and after the ripening process. The study also examined the impact of ripening on protein metabolism in pork sausages and compared the protein profiles of different sausage variants. The obtained research results indicate that dandelion-leaf extract (Taraxacum officinale) were rich in phenolic acids, flavonoids, coumarins, and their derivatives (LC-QTOF-MS method). Antiradical activity test against the ABTS+* and DPPH radical, and the TBARS index, demonstrated that addition of dandelion (0.5-1%) significantly improved the oxidative stability of raw-ripening sausages with nitrite content reduction to 80 mg/kg. A microbiological evaluation of the sausages was also carried out to assess the correctness of the ripening process. The total number of viable bacteria, lactic acid bacteria, and coliforms were evaluated and subsequently identified by mass spectrometry.

Investigation of the Effects of Phenolic Extracts Obtained from Agro-Industrial Food Wastes on Gelatin Modification

In this study, modified bovine gelatin was produced using the alkaline technique with four different oxidized agro-industrial food waste (pomegranate peel (PP), grape pomace and seed (GP), black tea (BT), and green tea (GT)) phenolic extracts (AFWEs) at three different concentrations (1, 3, and 5% based on dry gelatin). The effect of waste type and concentration on the textural, rheological, emulsifying, foaming, swelling, and color properties of gelatin, as well as its total phenolic content and antioxidant activity, was investigated. Significant improvement in gel strength, thermal stability, and gelation rate of gelatin was achieved by modification with oxidized agro-industrial waste extracts. Compared to the control sample, 46.24% higher bloom strength in the GT5 sample, 5.29 and 6.01 °C higher gelling and melting temperatures in the PP5 sample, respectively, and 85.70% lower tmodel value in the GT3 sample were observed. Additionally, the total phenolic content, antioxidant activity, foam, and emulsion properties of the modified gels increased significantly. This study revealed that gelatins with improved technological and functional properties can be produced by using oxidized phenolic extracts obtained from agricultural industrial food wastes as cross-linking agents in the modification of gelatin.

Structural, functional properties, and in vitro digestibility of sunflower protein concentrate as affected by extraction method: Isoelectric precipitation vs ultrafiltration

This study was the first to compare the structural features, functional properties and in vitro digestibility of two protein concentrates produced from defatted sunflower meal via two different three-stage processes (chlorogenic acid removal-alkaline extraction-isoelectric precipitation versus chlorogenic acid removal-alkaline extraction-ultrafiltration; concentrates termed AI-SPC and AU-SPC, respectively). Compared with AI-SPC, AU-SPC with a darker brown color had much higher protein recovery yield and purity, much higher solubility at pH 4-7, higher oil-holding capacity, greater emulsifying and foaming capacities at pH 7 and 9, and slightly lower foaming capacity at pH 3. The bioavailability was higher for AU-SPC after oral-gastric-intestinal digestion. Moreover, AI-SPC occurred as clumps/lumps of particles, whilst AU-SPC appeared as flat blocks with continuous surfaces. AU-SPC was more negatively charged, and had a smaller particle size, less β-sheet, more β-turn, slightly more α-helix structure. These results confirmed the close relationship between protein production methods and its functional properties and digestibility.

Co-assembled whey protein and proanthocyanidins as a promising biocarrier for hydrophobic pterostilbene: Fabrication, characterization, and cellular antioxidant potential

The usage of food-derived polyphenols with different polarities has been limited by their instability and incompatibility. Therefore, a biocarrier was developed by co-assembly of whey protein isolate (WPI) and hydrophilic proanthocyanidin (PC) for loading hydrophobic pterostilbene (PTE). Such biocarrier has superior affinity for PTE than WPI alone, as determined by encapsulation efficiency and loading capacity assay, fluorescence quenching analysis, and molecular docking, whereas the assembly process was characterized by particle size and zeta potential, 3-dimensional fluorescence, and scanning electron microscopy. Circular dichroism and Fourier transform infrared spectroscopy spectra confirmed the α-helix to β-sheet and random coil transition of proteins during the formation of nanocomplexes. Whey protein isolate acted as a mediator through altering the binding mode of PC and PTE, allowing them to perform significant synergistic effects in enhancing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging and reducing H2O2-induced cell damage. This research may serve to develop new protein/polyphenol co-loading systems and offer a reliable nutritional fortification.

Covalent conjugation of Inca peanut albumin and polyphenols with different phenolic hydroxyl numbers through laccase catalysis to improve functional properties

BACKGROUND

Enzymatic crosslinking is a method that can be used to modify Inca peanut albumin (IPA) using polyphenols, and provides desirable functionalities; however, the effect of polyphenol structures on conjugate properties is unclear. In this study, we selected four polyphenols with different numbers of phenolic hydroxyl groups [para-hydroxybenzoic acid (HBA), protocatechuic acid (PCA), gallic acid (GA), and epigallocatechin gallate (EGCG)] for covalent modification of IPA by enzymatic crosslinking, and explored the structure-function changes of the IPA-polyphenol conjugates.

RESULTS

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis showed that laccase successfully promoted covalent crosslinking of IPA with polyphenols, with the order of degree of conjugation as EGCG > GA > PCA > HBA, the IPA-EGCG conjugate showed the highest polyphenol binding equivalents (98.35 g kg-1 protein), and a significant reduction in the content of free amino, sulfhydryl, and tyrosine group. The oxidation of polyphenols by laccase forms quinone or semiquinone radicals that are covalently crosslinked to the reactive groups of IPA, leading to significant changes in the secondary and tertiary structures of IPA, with spherical structures transforming into dense lamellar structures. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability and emulsification stability of IPA-EGCG conjugates improved by almost 6-fold and 2.7-fold, respectively, compared with those of unmodified IPA.

CONCLUSION

These data suggest that the higher the number of polyphenol hydroxyl groups, the higher the degree of IPA-polyphenol conjugation; additionally, enzymatic crosslinking can significantly improve the functional properties of IPA. © 2024 Society of Chemical Industry.

The First Records of the In Silico Antiviral and Antibacterial Actions of Molecules Detected in Extracts of Algerian Fir (Abies numidica De Lannoy) Using LC-MS/MS Analysis

(1) Background: Due to the wide application in medicinal and pharmaceutical chemistry of flavonoid molecules, which are one of the most famous types of secondary plant metabolites, our work has come within the framework of bio-consulting to help in the identification of the molecule(s) responsible for the antibacterial effect which will be the active principle of a natural antibiotic developed from Algerian fir using bioinformatics tools. (2) Methods: The docking method was used to test the antiviral activity on SARS-CoV-2 virus and the antibacterial activity on Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli of 12 polyphenolic molecules present in the ethyl acetate and n-butanol extracts of Numidian fir leaves, and identify the molecules responsible for these specific biological activities. (3) Results: The findings revealed that it is possible that two molecules, hyperoside and quercitrin, have a high capacity to inhibit SARS-CoV-2, and it is important to mention that they are the most quantitatively abundant molecules in the extract. The molecule luteolin-7-glucoside is probably responsible for the antibacterial activity in the extract against Gram-negative bacteria such as Escherichia coli, and the molecule hesperidin is responsible for the antibacterial activity in the extract against Gram-positive bacteria such as Staphylococcus aureus.

Demonstration of the synergistic effect of biochar and Trichoderma harzianum on the development of Ralstonia solanacearum in eggplant

Soil degradation has been accelerated by the use of chemical pesticides and poor agricultural practices, which has had an impact on crop productivity. Recently, there has been a lot of interest in the use of eco-friendly biochar applications to enhance soil quality and sequester carbon in sustainable agriculture. This study aimed to determine the individual and combined effects of Leaf Waste Biochar (LWB) and the bio-control agent Trichoderma harzianum (BCA) on the development of bacterial wilt in eggplants (Solanum melongena) caused by Ralstonia solanacearum (RS). The effects of LWB and BCA on eggplant physiology and defense-related biochemistry were comprehensively examined. Inoculated (+RS) and un-inoculated (-RS) eggplants were grown in potting mixtures containing 3% and 6% (v/v) LWB, both with and without BCA. The percentage disease index was considerably reduced (90%) in plants grown in the 6% LWB+ BCA amended treatments. Moreover, the plants grown in LWB and inoculated with BCA had higher phenolics, flavonoids and peroxidase contents compared to the non-amended control. The level of NPK was significantly increased (92.74% N, 76.47% P, 53.73% K) in the eggplants cultivated in the 6% LWB + BCA composition. This study has shown that the association of T. harzianum with biochar improved plant growth and reduced R. solanacearum induced wilt. Furthermore, the combined impact of biochar and T. harzianum was greater in terms of wilt suppression and increase in plant physiological measurements when the biochar concentration was 6%. Biochar and bio-control agents triggered biochemical alterations, thus enhancing the management of disease-infested soils.

Comparison of Non-Covalent and Covalent Interactions between Lactoferrin and Chlorogenic Acid

Adding polyphenols to improve the absorption of functional proteins has become a hot topic. Chlorogenic acid is a natural plant polyphenol with anti-inflammatory, antioxidant, and anticancer properties. Bovine lactoferrin is known for its immunomodulatory, anticancer, antibacterial, and iron-chelating properties. Therefore, the non-covalent binding of chlorogenic acid (CA) and bovine lactoferrin (BLF) with different concentrations under neutral conditions was studied. CA was grafted onto lactoferrin molecules by laccase catalysis, free radical grafting, and alkali treatment. The formation mechanism of non-covalent and covalent complexes of CA-BLF was analyzed by experimental test and theoretical prediction. Compared with the control BLF, the secondary structure of BLF in the non-covalent complex was rearranged and unfolded to provide more active sites, the tertiary structure of the covalent conjugate was changed, and the amino group of the protein participated in the covalent reaction. After adding CA, the covalent conjugates have better functional activity. These lactoferrin-polyphenol couplings can carry various bioactive compounds to create milk-based delivery systems for encapsulation.

Hemp (Cannabis sativa L.) protein: Impact of extraction method and cultivar on structure, function, and nutritional quality

Hemp (Cannabis sativa L.) is increasingly gaining traction as a novel and sustainable source of plant protein. Accordingly, the aim of this study was to investigate the effectiveness of two protein extraction methods, alkaline extraction coupled with isoelectric precipitation (AE-IEP) and salt extraction coupled with ultrafiltration (SE-UF) in producing hemp protein isolates (pH-HPI and salt-HPI) with high purity and yield. Structural characterization as impacted by extraction method and cultivar was performed and related to functional performance and nutritional quality. Both extraction methods, with carefully selected parameters, resulted in HPI with high purity (86.6-88.1% protein) and protein extraction yields (81.6-87.3%). All HPI samples had poor solubility (∼9-20%) at neutral pH compared to commercial soy protein and pea protein isolates (cSPI, cPPI). A relatively high surface hydrophobicity and low surface charge contributed to such poor solubility of HPI. However, HPI demonstrated similar solubility at acidic pH (50-67%) and comparable gel strength (up to 24 N) to cSPI. Comparing experimental amino acid composition to the theoretical amino acid distribution in hemp protein provided insights to the functional performance of the protein isolates. While pH-HPI demonstrated better functionality than salt-HPI, minimal structural, functional, and nutritional differences were noted among the pH-HPI samples extracted from four different cultivars. Overall, results from this work could be used to guide future attempts to further develop successful protein extraction processes, and to provide valuable insights to propel breeding efforts that target enhanced hemp protein characteristics for food applications.

Effects of Different Phenolic Compounds on the Redox State of Myoglobin and Prevention of Discoloration, Lipid and Protein Oxidation of Refrigerated Longtail Tuna (Thunnus tonggol) Slices

Effects of different phenolic compounds on the redox state of myoglobin and their potential for preserving the color and chemical quality of refrigerated longtail tuna (Thunnus tonggol) slices were studied. Purified myoglobin from dark muscle (15.83 kDa) was prepared. Catechin, EGCG, quercetin, and hyperoside affected the absorption spectra and redox state of metmyoglobin (metMb) at 4 °C for up to 72 h differently. Reduction of metMb to oxymyoglobin (oxyMb) was notably observed for two flavonols (EGCG and quercetin) at 50 and 100 ppm. Based on the reducing ability of metMb, EGCG and quercetin were selected for further study. Longtail tuna slices were treated with EGCG and quercetin at 200 and 400 mg/kg. Color (a* and a*/b*), proportion of myoglobin content, and quality changes were monitored over 72 h at 4 °C. Tuna slices treated with 200 mg/kg EGCG showed better maintenance of oxyMb and color as well as lower lipid oxidation (PV and TBARS) and protein oxidation (carbonyl content) than the remaining samples. Nevertheless, EGCG at 400 mg/kg exhibited lower efficacy in retaining the quality of tuna slices. Thus, EGCG at 200 mg/kg could be used to maintain the color and prolong the shelf life of refrigerated longtail tuna slices.

A comprehensive multi-omics analysis, integrating proteomics and metabolomics, was employed to elucidate tea-induced stewed beef quality change mechanisms

To better understand the functional mechanism of four types of tea (green tea, black tea, jasmine tea, and dark tea) on the quality of stewed beef, changes in quality characteristics, proteomics, and metabolomics were investigated. Adding these four tea types decreased the pH value, L* value, shear force, and hardness of the stewed beef. Among these groups, black tea (BT) significantly improved the tenderness of the stewed beef. They have substantially impacted pathways related to protein oxidative phosphorylation, fatty acid degradation, amino acid degradation, and peroxisomes in stewed beef. The study identified that Myosin-2, Starch binding domain 1, Heat shock protein beta-6, and Myosin heavy chain four are significantly correlated with the quality characteristics of tea-treated stewed beef, making them potential biomarkers. Green tea (GT), black tea (BT), jasmine tea (JT), and dark tea (DT) led to the downregulation of 20, 36, 38, and 31 metabolites, respectively, which are lipids and lipid-like molecules in the stewed beef. The co-analysis of proteomics and metabolomics revealed that differential proteins significantly impacted metabolites associated with carbohydrates, amino acids, lipids, and other nutrients. This study determined the effects of four types of tea on the quality of stewed beef and their underlying mechanisms, providing valuable insights for applying of tea in meat products. At the same time, it can offer new ideas for developing fresh meat products.

Effects of walnut seed coat polyphenols on walnut protein hydrolysates: Structural alterations, hydrolysis efficiency, and acetylcholinesterase inhibitory capacity

The walnut meal is rich in nutrients such as protein from the kernel and polyphenolic compounds from the seed coat. However, the influences of seed coat polyphenols on walnut protein (WP) hydrolysis remained unclear. In this study, our findings indicated that polyphenols induced alterations in the secondary structure and amino acid composition of WP. These changes resulted in both a hindrance of hydrolysis and an enhancement of acetylcholinesterase (AChE) inhibition. Furthermore, four peptides of 119 identified peptides (LR, SF, FQ, and FR) were synthesized based on higher predicted bioactivity and Vinascores in silico. Among them, FQ showed interaction with amino acid residues in AChE through the formation of four π-π stacking bonds and two hydrogen bonds, resulting in the highest AChE inhibitory capacity. The combination index showed that chlorogenic acid derived from the seed coat and FQ at the molar ratio of 1:4 exhibited synergistic effects of AChE inhibition.

Interactions between proteins and phenolics: effects of food processing on the content and digestibility of phenolic compounds

Phenolic compounds have recently become one of the most interesting topics in different research areas, especially in food science and nutrition due to their health-promoting effects. Phenolic compounds are found together with macronutrients and micronutrients in foods and within several food systems. The coexistence of phenolics and other food components can lead to their interaction resulting in complex formation. This review article aims to cover the effects of thermal and non-thermal processing techniques on the protein-phenolic interaction especially focusing on the content and digestibility of phenolics by discussing recently published research articles. It is clear that the processing conditions and individual properties of phenolics and proteins are the most effective factors in the final content and intestinal fates of phenolic compounds. Besides, thermal and non-thermal treatments, such as high-pressure processing, pulsed electric field, cold plasma, ultrasonication, and fermentation may induce alterations  in those interactions. Still, new investigations are required for different food processing treatments by using a wide range of food products to enlighten new functional and healthier food product design, to provide the optimized processing conditions of foods for obtaining better quality, higher nutritional properties, and health benefits. © 2024 Society of Chemical Industry.

Investigating the mechanism of antioxidants as egg white powder flavor modifiers

BACKGROUND

The uses of egg white powder (EWP) are restricted because of its odor. It is necessary to find a method to improve its flavor. In this paper, three different antioxidants - green tea extract (GTE), sodium ascorbate (SA), and glutathione (GSH) - were selected to modify the flavor. The physicochemical and structural properties of EWP were investigated to study the mechanism of the formation and release of volatile compounds.

RESULTS

Antioxidants can modify the overall flavor of EWP significantly, inhibiting the generation or release of nonanal, 3-methylbutanal, heptanal, decanal, geranyl acetone, and 2-pemtylfuran. A SA-EWP combination showed the lowest concentration of 'off' flavor compounds; GTE-EWP and GSH-EWP could reduce several 'off' flavor compounds but increased the formation of geranyl acetone and furans. The changes in the carbonyl content and the amino acid composition confirmed the inhibition of antioxidants with the oxidative degradation of proteins or characteristic amino acids. The results of fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy provided structural information regarding EWP, which showed the release of volatile compounds decreased due to structural changes. For example, the surface hydrophobicity increased and the protein aggregation state changed.

CONCLUSIONS

Antioxidants reduce the 'off' flavor of EWP in two ways: they inhibit protein oxidation and Maillard reactions (they inhibit formation of 3-methylbutanal and 2-pemtylfuran) and they enhance the binding ability of heat-denatured proteins (reducing the release of nonanal, decanal, and similar compounds). © 2023 Society of Chemical Industry.

Co-encapsulation of curcumin and anthocyanins in bovine serum album-fucoidan nanocomplex with a two-step pH-driven method

BACKGROUND

Curcumin (CUR) and anthocyanins (ACN) are recommended due to their bioactivities. However, their nutritional values and health benefits are limited by their low oral bioavailability. The incorporation of bioactive substances into polysaccharide-protein composite nanoparticles is an effective way to enhance their bioavailability. Accordingly, this study explored the fabrication of bovine serum albumin (BSA)-fucoidan (FUC) hybrid nanoparticles using a two-step pH-driven method for the delivery of CUR and ACN.

RESULTS

Under a 1:1 weight ratio of BSA to FUC, the point of zero charge moved from pH ⁓ 4.7 for BSA to around 2.5 for FUC-coated BSA, and the formation of BSA-FUC nanocomplex was pH-dependent by showing the maximum CUR emission wavelength shifting from 546 nm (CUR-loaded BSA-FUC at pH 4.7) and 544 nm (CUR/ACN-loaded BSA-FUC nanoparticles at pH 4.7) to 540 nm (CUR-loaded BSA-FUC at pH 6.0) and 539 nm (CUR/ACN-loaded BSA-FUC nanoparticles at pH 6.0). Elevated concentrations of NaCl from 0 to 2.5 mol L-1 caused particle size increase from about 250 to about 800 nm, but showing no effect on the encapsulation efficiency of CUR. The CUR and ACN entrapped, respectively, in the inner and outer regions of the BSA-FUC nanocomplex were released at different rates. After incubation for 10 h, more than 80% of ACN was released, while less than 25% of CUR diffused into the receiving medium, which fitted well to Logistic and Weibull models.

CONCLUSION

In summary, the BSA-FUC nanocomposites produced by a two-step pH-driven method could be used for the co-delivery of hydrophilic and hydrophobic nutraceuticals. © 2023 Society of Chemical Industry.

Bioavailability and mechanisms of dietary polyphenols affected by non-thermal processing technology in fruits and vegetables

Plant polyphenols play an essential role in human health. The bioactivity of polyphenols depends not only on their content but also on their bioavailability in food. The processing techniques, especially non-thermal processing, improve the retention and bioavailability of polyphenolic substances. However, there are limited studies summarizing the relationship between non-thermal processing, the bioavailability of polyphenols, and potential mechanisms. This review aims to summarize the effects of non-thermal processing techniques on the content and bioavailability of polyphenols in fruits and vegetables. Importantly, the disruption of cell walls and membranes, the inhibition of enzyme activities, free radical reactions, plant stress responses, and interactions of polyphenols with the food matrix caused by non-thermal processing are described. This study aims to enhance understanding of the significance of non-thermal processing technology in preserving the nutritional properties of dietary polyphenols in plant-based foods. It also offers theoretical support for the contribution of non-thermal processing technology in improving food nutrition.

Emerging challenges and efficacy of polyphenols-proteins interaction in maintaining the meat safety during thermal processing

Polyphenols are well documented against the inhibition of foodborne toxicants in meat, such as heterocyclic amines, Maillard's reaction products, and protein oxidation, by means of their radical scavenging ability, metal chelation, antioxidant properties, and ability to form protein-polyphenol complexes (PPCs). However, their thermal stability, low polarity, degree of dispersion and polymerization, reactivity, solubility, gel forming properties, low bioaccessibility index during digestion, and negative impact on sensory properties are all questionable at oil-in-water interface. This paper aims to review the possibility and efficacy of polyphenols against the inhibition of mutagenic and carcinogenic oxidative products in thermally processed meat. The major findings revealed that structure of polyphenols, for example, molecular size, no of substituted carbons, hydroxyl groups and their position, sufficient size to occupy reacting sites, and ability to form quinones, are the main technical points that affect their reactivity in order to form PPCs. Following a discussion of the future of polyphenols in meat-based products, this paper offers intervention strategies, such as the combined use of food additives and hydrocolloids, processing techniques, precursors, and structure-binding relationships, which can react synergistically with polyphenols to improve their effectiveness during intensive thermal processing. This comprehensive review serves as a valuable source for food scientists, providing insights and recommendations for the appropriate use of polyphenols in meat-based products.

Bioaccessibility and antioxidant capacity of kefir-based smoothies fortified with kale and spinach after in vitro gastrointestinal digestion

The kefir-based smoothies with kale and spinach were designed as a ready-to-drink and innovative functional snack. Microbiological, physicochemical, as well as pre- and postgastrointestinal total antioxidant capacity (TAC; CUPRAC, DPPH, and FRAP) analyses were conducted. It was determined that the kefir-based smoothies with vegetables had higher ash, carbohydrate, and dietary fiber values. Fructose and glucose contents of smoothy with kale were high, while smoothy with spinach included high sucrose and maltose. The microbiology results revealed that kefir-based vegetable smoothies had minimum Lactobacillaceae viability (>log 7 cfu g-1) for the required functional effect after 14-day storage. Moreover, the addition of kale significantly increased (p < .01) the level of initial TAC (CUPRAC, DPPH, and FRAP) and total phenolic content (TPC) values. After in vitro gastric digestion analysis, smoothie with spinach demonstrated higher TAC and TPC values and the control sample had higher TAC and TPC values compared with a predigestion step. It was found that in vitro intestinal DPPH values were higher for the sample with spinach samples, while the sample with kale had the highest FRAP values. It was also found that the bioaccessibility indexes of plain kefir were determined to be the highest in both in vitro gastric and intestinal procedures. The present study provided novel insights into the in vitro digestion properties of kefir fortified with vegetables. Nevertheless, further studies are needed to identify the functional properties of the milk and plant matrices mixture using in vitro and in vivo trials.

Unveiling the Immunomodulatory Potential of Phenolic Compounds in Food Allergies

Food allergies are becoming ever more prevalent around the world. This pathology is characterized by the breakdown of oral tolerance to ingested food allergens, resulting in allergic reactions in subsequent exposures. Due to the possible severity of the symptoms associated with this pathology, new approaches to prevent it and reduce associated symptoms are of utmost importance. In this framework, dietary phenolic compounds appear as a tool with a not fully explored potential. Some phenolic compounds have been pointed to with the ability to modulate food allergies and possibly reduce their symptoms. These compounds can modulate food allergies through many different mechanisms, such as altering the bioaccessibility and bioavailability of potentially immunogenic peptides, by modulating the human immune system and by modulating the composition of the human microbiome that resides in the oral cavity and the gastrointestinal tract. This review deepens the state-of-the-art of the modulation of these mechanisms by phenolic compounds. While this review shows clear evidence that dietary supplementation with foods rich in phenolic compounds might constitute a new approach to the management of food allergies, it also highlights the need for further research to delve into the mechanisms of action of these compounds and decipher systematic structure/activity relationships.

Conjugation of lesser mealworm (Alphitobius diaperinus) larvae protein with polyphenols for the development of innovative antioxidant emulsifiers

Lesser mealworm protein concentrate (LMPC) was conjugated with chlorogenic acid (CA) or tannic acid (TA) using an alkaline method. The impact of polyphenol type and concentration on the physicochemical and structural characteristics, antioxidant, interfacial, and emulsifying properties of the LMPC-polyphenol conjugates were investigated. Under the conditions tested, TA demonstrated higher affinity for LMPC compared to CA. The conjugation of LMPC induced conformational changes as showed by intrinsic fluorescence and FT-MIR raw spectra analysis. The surface hydrophobicity of the conjugates was reduced, leading to increased interfacial tension values for LMPC-TA conjugates without impairment of the emulsifying activity. The antioxidant properties were significantly improved by the conjugation. Flaxseed oil-in-water (O/W) emulsions stabilized by the conjugates and LMPC remained physically stable for 12 days at 50 °C with a notable reduction of secondary oxidation products when conjugates were used. LMPC-TA and LMPC-CA exhibited potential to be used as novel antioxidant emulsifiers in O/W emulsions.

New Horizons of Covalent Complex of Plant-Derived Recombinant Human Lactoferrin (OsrhLF) Combined with Different Polyphenols: Formation, Physicochemical Properties, and Gastrointestinal Fate

Four typical dietary polyphenols ((-)-epigallocatechin gallate (EGCG), quinic acid (QA), caffeic acid (CA), and ferulic acid (FA)) were covalently prepared with rice recombinant human lactoferrin (OsrhLF) and bovine lactoferrin (bLF), and their structure and physicochemical properties were investigated, different lycopene emulsions were made by ultrasonic emulsification to analyze gastrointestinal fate. The results indicated that the covalent modification polyphenols changed the secondary/tertiary structure of LF, significantly improving the surface hydrophilicity, thermal stability, and antioxidant activity of LF. Compared with the bLF group, the OsrhLF group was more hydrophilic and the thermal denaturation temperature of the OsrhLF-CA reached 104.4 °C. LF-polyphenol emulsions significantly enhanced the photochemical stability and bioavailability of lycopene and achieved effective encapsulation and protection of lycopene compared to free lycopene, and the OsrhLF-EGCG reached 58.94% lycopene bioavailability. In short, OsrhLF does not differ much from bLF in terms of physicochemical properties and has a strong potential in the field of dietary supplements.

Proanthocyanidins isolated from the leaves of Ficus glomerata evaluated on the activities of rumen enzymes: in vitro and in silico studies

Two new proanthocyanidins (2S:3S)-(-)-epicatechin-(4α→8)4-(2R:3R)-(+)-catechin (Compound 1) and (2R, 3R)-3-O-galloyl-(+)-catechin (4β→8)3-(2R, 3R)-3-O-galloyl-(+)-catechin (Compound 2) were isolated from Ficus glomerata and characterized by ultraviolet spectroscopy (UV), proton nuclear magnetic resonance (1H NMR), 13C NMR, and heteronuclear multiple bond correlation . The bioactivity and drug scores of isolated compounds were predicted using OSIRIS property explorer applications with drug scores of 0.03 (compound 1) and 0.05 (compound 2). Predictive drug scores provided an indication of the compounds' potential to demonstrate desired biological effects. Furthermore, the newly discovered proanthocyanidins tended to interact with protein due to their chemical structure and molecular conformation. With the aim of maintaining this focus, compounds 1 and 2 were subjected to in vitro testing against ruminal enzymes to further explore their potential impact. Both compounds showed significant inhibition activities (p < 0.01) against glutamic oxaloacetic transaminase in both protozoa and bacterial fractions, with an effective concentration (EC50) of 12.30-18.20 mg/mL. The compounds also exhibited significant inhibition (p < 0.01) of ruminal glutamic pyruvic transaminase activity, with EC50 values ranging from 9.77 to 17.38 mg/mL. Furthermore, the inhibition was recorded in R-cellulase between EC50 values of 15.85 and 23.99 mg/mL by both compounds. Additionally, both compounds led to a decrease in protease activity with increasing incubation time and concentration. In conclusion, the results indicate that these novel proanthocyanidins hold the potential to significantly impact rumen enzyme biology. Furthermore, their promising effects suggest that they could be further explored for drug development and other important applications.

Comparative analysis of Chrysoporthe cubensis exoproteomes and their specificity for saccharification of sugarcane bagasse

The phytopathogenic fungus Chrysoporthe cubensis is a relevant source of lignocellulolytic enzymes. This work aimed to compare the profile of lignocellulose-degrading proteins secreted by C. cubensis grown under semi-solid state fermentation using wheat bran (WB) and sugarcane bagasse (SB). The exoproteomes of the fungus grown in wheat bran (WBE) and sugarcane bagasse (SBE) were qualitative and quantitatively analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Data are available via ProteomeXchange with identifier PXD046075. Label-free proteomic analysis of WBE and SBE showed that the fungus produced a spectrum of carbohydrate-active enzymes (CAZymes) with exclusive characteristics from each extract. While SBE resulted in an enzymatic profile directed towards the depolymerization of cellulose, the enzymes in WBE were more adaptable to the degradation of biomass rich in hemicellulose and other non-lignocellulosic polymers. Saccharification of alkaline pre-treated sugarcane bagasse with SBE promoted glucose release higher than commercial cocktails (8.11 g L-1), while WBE promoted the higher release of xylose (5.71 g L-1). Our results allowed an in-depth knowledge of the complex set of enzymes secreted by C. cubensis responsible for its high lignocellulolytic activity and still provided the identification of promising target proteins for biotechnological applications in the context of biorefinery.

Effects of plant polyphenols on lipid oxidation in pea and soy protein solutions

Significant lipid-derived off-flavors hinder broader acceptance and applicability of plant protein ingredients. Polyphenols are strong antioxidants and can react with protein and carbonyl compounds to reduce oxidative off-flavor development. The effects of polyphenols (catechin, tannic acid (TA), grape seed extract (GSE), and green tea extract (GTE)) on lipid oxidation in pea and soy protein solutions were investigated. All polyphenols reduced lipid oxidation products and volatile compound concentration versus their respective controls. TA, GSE, and GTE reduced the secondary products in pea and soy proteins by an average of 75 % and 50 %, respectively, versus controls, compared to catechin's 61 % and 13 %, respectively. The chemical structures of TA, GSE, and GTE likely allowed them to interact more effectively than catechin with proteins, especially lipoxygenase. However, no significant differences between the polyphenols' antioxidant capacities were observed. Thus, polyphenols predominantly reduced lipid oxidation via interactions with proteins, rather than electron transfer or radical quenching.

Effects of conjugated interactions between Perilla seed meal proteins and different polyphenols on the structural and functional properties of proteins

The study aims to perform alkali-induced covalent modification of perilla seed meal protein (PSMP) using different polyphenols: gallic acid (GA), protocatechuic acid (PCA), caffeic acid (CA), apigenin (API) and luteolin (LU). Covalent binding between different polyphenols and PSMP was found to occur, with PSMP-LU showing the highest binding rate of 90.89 ± 1.37 mg/g; the fluorescence spectrum of PSMP-CA showed a maximum blue shift of Δ13.4 nm; the solubility increased from 69.626 ± 1.39 % to 83.102 ± 0.98 %. In order to better understand how these covalent conjugates, stabilize -carotene in emulsions, they were utilized as emulsifiers in an emulsion delivery method. The work further reveals the formation of PSMP-polyphenol conjugates and develops a novel emulsification system to deliver readily decomposable functional factors, providing a potential scenario for the application of PSMP and bioactive conjugates.

Effect of Germination on the Physicochemical Properties, Functional Groups, Content of Bioactive Compounds, and Antioxidant Capacity of Different Varieties of Quinoa (Chenopodium quinoa Willd.) Grown in the High Andean Zone of Peru

Germination is an effective strategy to improve the nutritional and functional quality of Andean grains such as quinoa (Chenopodium quinoa Willd.); it helps reduce anti-nutritional components and enhance the digestibility and sensory aspects of the germinated. This work aimed to evaluate the effect of germination (0, 24, 48, and 72 h) on the physicochemical properties, content of bioactive compounds, and antioxidant capacity of three varieties of quinoa: white, red, and black high Andean from Peru. Color, nutritional composition, mineral content, phenolic compounds, flavonoids, and antioxidant activity were analyzed. Additionally, infrared spectra were obtained to elucidate structural changes during germination. The results showed color variations and significant increases (p < 0.05) in proteins, fiber, minerals, phenolic compounds, flavonoids, and antioxidant capacity after 72 h of germination, attributed to the activation of enzymatic pathways. In contrast, the infrared spectra showed a decrease in the intensity of functional groups -CH-, -CH2-, C-OH, -OH, and C-N. Correlation analysis showed that flavonoids mainly contributed to antioxidant activity (r = 0.612). Germination represents a promising alternative to develop functional ingredients from germinated quinoa flour with improved nutritional and functional attributes.

A comparative study of the digestion behavior and functionality of protein from chia (Salvia hispanica L.) ingredients and protein fractions

Protein derived from chia (Salvia hispanica L.), characterized by a balanced amino acid composition, represents a potentially healthier and environmentally friendly alternative poised for innovation within the plant-based food sector. It was hypothesized that the growing location of chia seeds and processing techniques used might influence protein digestion patterns, which in turn could affect the biological functions of the digestion products. To examine this hypothesis, we assessed the gastrointestinal fate of degummed-defatted flour (DDF), protein concentrate (PC), and isolated albumin (Alb) and globulin (Glo) fractions. Furthermore, we compared the antioxidant and anti-inflammatory activities of the resulting digesta by means of in vitro and cellular assays. Post-gastrointestinal digestion, the PC exhibited elevated levels of soluble protein (7.6 and 6.3 % for Mexican and British PC, respectively) and peptides (24.8 and 27.9 %, respectively) of larger molecular sizes compared to DDF, Alb, and Glo. This can be attributed to differences in the extraction/fractionation processes. Leucine was found to be the most prevalent amino acids in all chia digesta. Such variations in the digestive outcomes of chia protein components significantly influenced the bioactivity of the intestinal digestates. During gastrointestinal transit, British Glo exhibited the best reactive oxygen species (ROS) inhibition activity in oxidative-stressed RAW264.7 macrophages, while Mexican digesta outperformed British samples in terms of ROS inhibition within the oxidative-stressed Caco-2 cells. Additionally, both Mexican and British Alb showed effectively anti-inflammatory potential, with keratinocyte chemoattractant (KC) inhibition rate of 82 and 91 %, respectively. Additionally, Mexican PC and Alb generally demonstrated an enhanced capacity to mitigate oxidative stress and inflammatory conditions in vitro. These findings highlight the substantial potential of chia seeds as functional food ingredients, resonating with the shifting preferences of health-conscious consumers.