Polyphenol interactions with whey protein isolate and whey protein isolate–pectin coacervates

Tailoring carrier-free nanoparticles based on natural small molecule assembly for synergistic anti-tumor efficacy

Interfacial modular assemblies of versatile polyphenols have attracted widespread interest in surface and materials engineering. In this study, natural polyphenol (tannic acid, TA) and nobiletin (NOB) can directly form binary carrier-free spherical nanoparticles (NT NPs) through synergistically driven by a variety of interactions (such as hydrogen bonding, oxidative reactions, etc.). The synthesis involves polyphenolic deposition on hydrophobic NOB nanoaggregates, followed by in situ oxidative self-polymerization. Interestingly, the assembled NT NPs exhibit controllable and dynamic changes in particle size during the initial stage. Ultimately, uniform and spherical NT NPs appear stable, with high loading capability, enabling incorporated NOB to preserve their function. Furthermore, in vitro evaluations demonstrate that the rational combination of polyphenol module and NOB can induce apoptosis and inhibit tumor metastasis for both lung cancer H1299 and human fibrosarcoma HT1080 cell lines. Notably, the optimized NT48 NPs were then verified in vivo experiments to achieve a promising synergistic anti-tumor efficacy. These findings not only provide new opportunities for the streamlined and sensible engineering of future polyphenol-based biomaterials, but also open up new prospects for the design of small-molecule nature phytochemicals.

Enhancing walnut butter with a pea protein isolate-pectin-pterostilbene complex: Physicochemical properties and stability analysis

To explore the potential applications of pea protein isolate-pectin-pterostilbene complex (PPI-PEC-PT) in the sauce industry, its solubility, antioxidant capacity and oxidative stability were measured. The results indicated that PPI-PEC-PT exhibited a solubility of 77.67 %, more than double that of PPI-PT (31.93 %). The DPPH radical scavenging capacity of PPI-PEC-PT reached up to 78.52 % at a concentration of 50 μg/mL. After accelerated oxidation (60 °C, 7 days), the peroxide value (8.15 mmol/L) and malondialdehyde content (11.50 mmol/L) of PPI-PEC-PT emulsion were significantly lower than those of PPI. Additionally, when applied to walnut butter, PPI-PEC-PT significantly enhanced its gel properties. In conclusion, PPI-PEC-PT could not only serve as a natural antioxidant but also be utilized as a food additive to enhance the gelling properties of products in the food industry.

Preparation, characterization, and stability of pectin-whey protein isolate-based nanoparticles with mitochondrial targeting ability

Quercetin (Que) is a polyhydroxy flavonoid with strong inhibitory activity against cancer cells. However, the poor water solubility and low bioavailability of Que. limit its application in the functional food industry. In the present study, the nanoparticle loaded with Que. was prepared with whey isolate protein (WPI) stabilized by triphenylphosphonium bromide (TPP) and pectin (P) as wall materials. The formation mechanism, release of Que., and antitumor activity of nanoparticles were investigated. The results showed that the optimal ratio of WPI: TPP: Que.: P in the preparation of nanoparticles (WPI-TPP-Que-P) was 50:8:1:20 (w/w/w/w). The encapsulation rate of Que. in the WPI-TPP-Que-P was 82.64 % with a particle size of 261.7 nm and a zeta potential of -42.1 mV. Compared with WPI-TPP-Que, the retention rate of WPI-TPP-Que-P increased by 4.03 % after in vitro digestion. The release kinetic result indicated that WPI-TPP-Que-P release was dominated by non-Fickian diffusion. In addition, WPI-TPP-Que-P was taken in and achieved intracellular targeting to mitochondria and promoted apoptosis (apoptosis rate: 83.6 %) by decreasing mitochondrial membrane potential and IL-10 content and improving the content of TNF-α in HepG-2 cells. This study highlights the promising application of P-modified mitochondria-targeted nanocarriers for enhanced Que. delivery.

Changes in the structural, aggregation behavior and gel properties of pork myofibrillar protein induced by theaflavins

This study explores the effect of different theaflavins (TFs) concentrations (0, 100, 300, 600 and 900 mg/L) on the structure, aggregation behavior and gelation properties of pork myofibrillar protein (MP). The protein structure and aggregation behavior were characterized by free sulfhydryl groups, surface hydrophobicity, fluorescence emission spectra, particle size and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The gel properties of samples were characterized by gel strength, cooking loss, microstructure and gel supernatant SDS-PAGE. The results showed a significant decrease in free thiol content with increasing TFs concentration, suggesting thiol-quinone covalent interaction between TFs and thiol group of MP. Intrinsic fluorescence spectroscopy confirmed a static quenching between TFs and MP. And TFs reduced the particle size of MP suspension and caused no protein aggregation bond in SDS-PAGE. For gel properties, TFs caused a decrease of gel strength from 96.77 g to 21.91 g and an increase in cooking loss from 40.34 % to 71.15 %. The bond of protein aggregates in gel supernatants SDS-PAGE revealed that some protein aggregates formed by disulfide bonding were not involve in gel formation with TFs addition. In conclusion, TFs cause thiol loss of MP and impaired MP gelling ability by interfering with disulfide bond formation during gelation.

Physicochemical Properties, Stability, and Functionality of Non-Covalent Ternary Complexes Fabricated with Pea Protein, Hyaluronic Acid and Chlorogenic Acid

The aim of this study was to prepare and characterize stable non-covalent ternary complexes based on pea protein (PP, 0.5%), hyaluronic acid (HA, 0.125%), and chlorogenic acid (CA, 0~0.03%). The ternary complexes were comprehensively evaluated for physicochemical attributes, stability, emulsifying capacities, antioxidant properties, and antimicrobial efficacy. PP-HA binary complexes were first prepared at pH 7, and then CA was bound to the binary complexes, as verified by fluorescence quenching. Molecular docking elucidated that PP interacted with HA and CA through hydrogen bonding, hydrophobic and electrostatic interactions. The particle size of ternary complexes initially decreased, then increased with CA concentration, peaking at 0.025%. Ternary complexes demonstrated good stability against UV light and thermal treatment. Emulsifying activity of complexes initially decreased and then increased, with a turning point of 0.025%, while emulsion stability continued to increase. Complexes exhibited potent scavenging ability against free radicals and iron ions, intensifying with higher CA concentrations. Ternary complexes effectively inhibited Staphylococcus aureus and Escherichia coli, with inhibition up to 0.025%, then decreasing with CA concentration. Our study indicated that the prepared ternary complexes at pH 7 were stable and possessed good functionality, including emulsifying properties, antioxidant activity, and antibacterial properties under certain concentrations of CA. These findings may provide valuable insights for the targeted design and application of protein-polysaccharide-polyphenol complexes in beverages and dairy products.

A Novel Method for the Preparation of Casein-Fucoidan Composite Nanostructures

The aim of the study was to develop casein-fucoidan composite nanostructures through the method of polyelectrolyte complexation and subsequent spray drying. To determine the optimal parameters for the preparation of the composite structures and to investigate the influence of the production and technological parameters on the main structural and morphological characteristics of the obtained structures, 3(k-p) fractional factorial design was applied. The independent variables (casein to fucoidan ratio, glutaraldehyde concentration, and spray intensity) were varied at three levels (low, medium, and high) and their effect on the yield, the average particle size, and the zeta potential were evaluated statistically. Based on the obtained results, models C1F1G1Sp.30, C1F1G2Sp.40, and C1F1G3Sp.50, which have an average particle size ranging from (0.265 ± 0.03) µm to (0.357 ± 0.02) µm, a production yield in the range (48.9 ± 2.9) % to (66.4 ± 2.2) %, and a zeta potential varying from (-20.12 ± 0.9) mV to (-25.71 ± 1.0) mV, were selected as optimal for further use as drug delivery systems.

Advances in protein-based microcapsules and their applications: A review

Due to their excellent emulsification, biocompatibility, and biological activity, proteins are widely used as microcapsule wall materials for encapsulating drugs, natural bioactive substances, essential oils, probiotics, etc. In this review, we summarize the protein-based microcapsules, discussing the types of proteins utilized in microcapsule wall materials, the preparation process, and the main factors that influence their properties. Additionally, we conclude with examples of the vital role of protein-based microcapsules in advancing the food industry from primary processing to deep processing and their potential applications in the biomedical, chemical, and textile industries. However, the low stability and controllability of protein wall materials lead to degraded performance and quality of microcapsules. Protein complexes with polysaccharides or modifications to proteins are often used to improve the thermal instability, pH sensitivity, encapsulation efficiency and antioxidant capacity of microcapsules. In addition, factors such as wall material composition, wall material ratio, the ratio of core to wall material, pH, and preparation method all play critical roles in the preparation and performance of microcapsules. The application area and scope of protein-based microcapsules can be further expanded by optimizing the preparation process and studying the microcapsule release mechanism and control strategy.

Physical Stability and Antioxidant Ability of a Sustainable Oil-in-Water Emulsion Containing Perilla Skin Extract and Upcycled Aquasoya Powder

In response to environmental issues, upcycling has become a growing trend in the food industry. Aquasoya is a promising method to upcycle by-product from soybean processing due to its high protein contents and excellent emulsifying ability. In the present research, Aquasoya powder was used an emulsifier to incorporate the antioxidant compounds from perilla skin extract (PSE), namely rosmarinic acid, into oil-in-water (O/W) emulsion system and its physochemical stability was assessed. As a result, droplet size of the emulsion was smaller in PSE-incorporated emulsion (PO, 350.57 ± 9.60 b nm) than the emulsion without PSE (PX, 1045.37 ± 142.63 a nm). Centrifugal photosedimentometry analysis also revealed that the physical stability was significantly improved in PO, and the stability was maintained over 30 d of storage. Furthermore, as PO had a higher ABTS radical scavenging ability and showed slower initial lipid oxidation, it was concluded that PO has a higher antioxidant ability than PX. Conclusively, Aquasoya can be considered as an emulsifier in O/W emulsion with PSE because it can effectively integrate and stabilize the antioxidant substance derived from perilla skin.

Nanoencapsulation of Anthocyanins from Red Cabbage (Brassica oleracea L. var. Capitata f. rubra) through Coacervation of Whey Protein Isolate and Apple High Methoxyl Pectin

Encapsulation is a valuable strategy to protect and deliver anthocyanins (ACNs), phenolic compounds with outstanding antioxidant capacity but limited stability. In this study, coacervation was used to encapsulate an ACN-rich red cabbage extract (RCE). Two agri-food by-product polymers, whey protein isolate (WPI) and apple high-methoxyl pectin (HMP), were blended at pH 4.0 in a specific ratio to induce the formation of nanoparticles (NPs). The process optimisation yielded a monodispersed population (PDI < 0.200) of negatively charged (-17 mV) NPs with an average diameter of 380 nm. RCE concentration influenced size, charge, and antioxidant capacity in a dose-dependent manner. NPs were also sensitive to pH increases from 4 to 7, showing a progressive breakdown. The encapsulation efficiency was 30%, with the retention of ACNs within the polymeric matrix being influenced by their chemical structure: diacylated and/or C3-triglucoside forms were more efficiently encapsulated than monoacylated C3-diglucosides. In conclusion, we report a promising, simple, and sustainable method to produce monodispersed NPs for ACN encapsulation and delivery. Evidence of differential binding of ACNs to NPs, dependent on specific acylation/glycosylation patterns, indicates that care must be taken in the choice of the appropriate NP formulation for the encapsulation of phenolic compounds.

Reducing the Flocculation of Milk Tea Using Different Stabilizers to Regulate Tea Proteins

The regulation of flocs derived from polyphenol–protein formation in milk tea has not been fully explored. In this study, the flocculation of milk tea was regulated by adding 10 kinds of stabilizers with different characteristics. The stability coefficient and centrifugal precipitation rate were used as indexes. The optimal concentration ratio of the complex stabilizer was identified using the response surface methodology (RSM), being 0.04% for Arabic gum, 0.02% for β-cyclodextrin and 0.03% for Agar. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the characteristics of different stabilizers in milk tea, and our findings were as follows: (1) The relative strength of the peaks in different stable systems was different. The absorption peaks were mainly near the wave numbers 3376 cm−1, 2928 cm−1, 1655 cm−1, 1542 cm−1, 1408 cm−1, 1047 cm−1 and 925 cm−1. (2) The milk tea system was an amorphous structure. The diffraction peak of the composite system was observed to be about 20°. The crystallinity of the milk tea in the compound group was 33.16%, which was higher than that of the blank group (9.67%). (3) The compound stabilizer reduced flocculation, and the stabilizing agents improved the surface order of milk tea. These results indicate that the combination of polysaccharide stabilizers (Arabic gum and agar) and oligosaccharide stabilizers (β-CD) in certain proportions can regulate the flocculation of milk tea and improve its stability. The potential research avenues involving polyphenol–protein complex instability systems and their applications in food development are expanded by this work.

Structural, Binding and Functional Properties of Milk Protein-Polyphenol Systems: A Review

Polyphenols (PP) are linked to health benefits (e.g., prevention of cancer, cardiovascular disease and obesity), which are mainly attributed to their antioxidant activity. During digestion, PP are oxidised to a significant degree reducing their bio-functionality. In recent years, the potential of various milk protein systems, including β-casein micelles, β-lactoglobulin aggregates, blood serum albumin aggregates, native casein micelles and re-assembled casein micelles, to bind and protect PP have been investigated. These studies have yet to be systematically reviewed. The functional properties of the milk protein-PP systems depend on the type and concentration of both PP and protein, as well as the structure of the resultant complexes, with environmental and processing factors also having an influence. Milk protein systems protect PP from degradation during digestion, resulting in a higher bioaccessibility and bioavailability, which improve the functional properties of PP upon consumption. This review compares different milk protein systems in terms of physicochemical properties, PP binding performance and ability to enhance the bio-functional properties of PP. The goal is to provide a comprehensive overview on the structural, binding, and functional properties of milk protein-polyphenol systems. It is concluded that milk protein complexes function effectively as delivery systems for PP, protecting PP from oxidation during digestion.

Fabrication and characterization of gelatin-EGCG-pectin ternary complex: formation mechanism, emulsion stability, and structure

BACKGROUND

Protein-polyphenol-polysaccharide ternary complex particles have better emulsion interfacial stability compared to protein-polysaccharide binary complexes. However, knowledge is scarce when it comes to the fabrication of protein-polyphenol-polysaccharide ternary complexes as interfacial stabilizers and the interactions between the three substances. In the present work, ternary complexes were prepared using gelatin, high methoxyl pectin, and epigallocatechin gallate (EGCG) as raw materials. The effect of different influencing factors on the formation process of ternary complexes was investigated by varying different parameters. physicochemical stability, emulsifying properties, and structural characteristics were analyzed.

RESULTS

The ternary complex had a smaller particle size (275 nm) and polydispersity index (0.112) when the mass concentration ratio of gelatin to high methoxyl pectin was 9:1, addition of EGCG was 0.05%, pH value was 3.0, and ionic strength was 10 mmol L^-1 . Meanwhile, the complex had the highest emulsifying stability index (691.75 min) and emulsifying activity index (22.96 m²  g^-1 ). Scanning electron microscopical observation demonstrated that the addition of EGCG promoted the dispersion of ternary complex more uniformly, and effectively reduced the agglomeration phenomenon. The discrepancy in fluorescence intensity suggested that interactions between EGCG and gelatin occurred, which altered the protein spatial conformation of gelatin. Fourier transform infrared spectroscopic analysis elucidated that hydrogen bond interaction was the primary non-covalent interaction between EGCG and gelatin-high methoxyl pectin binary complex.

CONCLUSION

The aforementioned results purposed to provide some theoretical reference and basis for the rational design of stable protein-polyphenol-polysaccharide ternary complexes. © 2022 Society of Chemical Industry.

The Effects of Ethanol and Rutin on the Structure and Gel Properties of Whey Protein Isolate and Related Mechanisms

The effects of different levels of rutin (0, 0.05%, 0.1%, 0.2% and 0.3% w/v) and ethanol on the structure and gel properties of whey protein isolate (WPI) were examined. The results showed that the addition of ethanol promoted the gel formation of WPI. The addition of rutin increased the gel strength of WPI and maintained the water-holding capacity of the gel. Ethanol caused an increase in thiol content and surface hydrophobicity, but rutin decreased the thiol content and surface hydrophobicity of WPI. The particle size, viscosity and viscoelasticity of WPI increased at rutin levels of 0.2% and 0.3%, indicating that rutin caused cross-linking and aggregation of WPI, but rutin had no significant effect on the zeta-potential, indicating that electrostatic interactions were not the main force causing the changes in protein conformation and gel properties. Ethanol and rutin improved the gel properties of WPI possibly by inducing cross-linking of WPIs via hydrophobic and covalent interactions.

Dual improvement in curcumin encapsulation efficiency and lyophilized complex dispersibility through ultrasound regulation of curcumin-protein assembly

Ultrasound has a recognized ability to modulate the structure and function of proteins. Discovering the influential mechanism of ultrasound on the intramolecular interactions of egg-white protein isolate-curcumin (EPI-Cur) nanoparticles and their intermolecular interaction during freeze drying and redispersion is meaningful. In this study, under the extension of pre-sonication time, the protein solubility, surface hydrophobicity, and curcumin encapsulation rate showed an increasing trend, reaching the highest value at 12 min of treatment. However, the values decreased under the followed extension of ultrasound time. After freeze drying and redispersion were applied, the EPI-Cur sample under 12 min of ultrasound treatment exhibited minimal aggregation degree and loss of curcumin. The retention and loading rates of curcumin in the lyophilized powder reached 96 % and 33.60 mg/g EPI, respectively. However, under excessive ultrasound of >12 min, scanning electron microscopy showed distinct blocky aggregates. Overexposure of the hydrophobic region of the protein triggered protein-mediated hydrophobic aggregation after freeze drying. X-ray diffraction patterns showed the highest crystallinity, indicating that the free curcumin-mediated hydrophobic aggregation during freeze drying was enhanced by the concentration effect and intensified the formation of larger aggregates. This work has practical significance for developing the delivery of hydrophobic active substances. It provides theoretical value for the dynamic dispersity change in protein-hydrophobic active substances during freeze drying and redissolving.

Value-added salad dressing enriched with red onion skin anthocyanins entrapped in different biopolymers

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The microencapsulation of ROS extract was performed by gelation and freeze-drying.

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The powders were rich in valuable antioxidants, with over 80% EE for anthocyanins.

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Good stability of phytochemicals over storage and digestion was noticed.

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V2 powder’s functionality was tested by its addition to salad dressing.

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Our results are promising in developing multifunctional ingredients for foods.

In this study, red onion skin extract was used to obtain food ingredients. Complex biopolymeric matrices were dissolved in the anthocyanin-rich aqueous extract, followed by gelation and freeze-drying. Powders were characterized regarding encapsulation efficiency (EE), phytochemical content, color, antioxidant activity, and microstructure. Storage and simulated digestion stability were also assessed. Two powders with high contents of bioactives and antioxidant activity were obtained. The highest EE was acquired for the powder with a higher polysaccharides concentration (V2). In addition, V2 exhibited the best storage stability. The in vitro studies demonstrated that increased carbohydrate concentration delivers the best anthocyanins protection. To prove its functionality, V2 was added to a salad dressing. The addition of powder has improved the concentration of biologically active compounds and the antioxidant activity of the salad dressings. These results support the assumption that microencapsulation may deliver bioactives from red onion skin as functional ingredients for value-added foods.

A dark purple multifunctional ingredient from blueberry pomace enhanced with lactic acid bacteria for various applications

Nowadays, large quantities of berries are still being dumped or used for composting and animal feeding. The objective of this study was to customize a technological design for appropriate valorization of blueberry pomace into a shelf-life-stable, dark purple multifunctional ingredient, containing lactic acid bacteria (Lactobacillus casei), by freeze-drying. The main anthocyanins in blueberries freeze-dried inoculated pomace are malvidin 3-O-glucoside, peonidin 3-O-glucoside, and cyanidin 3-O-glucoside. A viable cells content of 4.75×10⁸ CFU/g DW was found after freeze-drying and the ability of the freeze-dried powder to inhibit the DPPH radical was 171.98 ± 1.73 mMol Trolox/g DW. The results obtained from CIElab analysis show a tendency to red and blue, characteristic of blueberry anthocyanins. The bioaccesibility of anthocyanins from blueberry powder was 37.8% and the probiotic survival rate after passing through the digestion process was 49.56%. The inhibitory potential of the obtained powder on α-amylase, pancreatic lipase, and α-glucosidase and tyrosinase was assessed. A significant antidiabetic potential of the powder was found, with IC50 values for α-amylase of 2.61 ± 0.24 mg/ml and for α-glucosidase of 1.37 ± 0.01 mg/ml, significantly lower when compared to corresponding drugs used in current practices. The powder also showed a significant potential to inhibit tyrosinase, supporting the hypothesis that the pomace resulting from juice and wine manufacturing may be successfully used to develop multifunctional ingredients with significant health benefits. PRACTICAL APPLICATION: Nowadays, food scientists and industry are seeking technological alternatives to obtain functional ingredients, due to the global interest in translating and applying scientific knowledge to address consumers' health issues. In our study, a freeze-drying customized design involving the use of the blueberry pomace, pectin, and Lactobacillus casei was applied to develop an ingredient with multiple functions. Besides a remarkable color, the powder showed good antioxidant activity, in vitro cells viability, and inhibitory activity against some metabolic syndrome-associated enzymes.

Tannic acid: a versatile polyphenol for design of biomedical hydrogels

Tannic acid (TA), a natural polyphenol, is a hydrolysable amphiphilic tannin derivative of gallic acid with several galloyl groups in its structure. Tannic acid interacts with various organic, inorganic, hydrophilic, and hydrophobic materials such as proteins and polysaccharides via hydrogen bonding, electrostatic, coordinative bonding, and hydrophobic interactions. Tannic acid has been studied for various biomedical applications as a natural crosslinker with anti-inflammatory, antibacterial, and anticancer activities. In this review, we focus on TA-based hydrogels for biomaterials engineering to help biomaterials scientists and engineers better realize TA's potential in the design and fabrication of novel hydrogel biomaterials. The interactions of TA with various natural or synthetic compounds are deliberated, discussing parameters that affect TA-material interactions thus providing a fundamental set of criteria for utilizing TA in hydrogels for tissue healing and regeneration. The review also discusses the merits and demerits of using TA in developing hydrogels either through direct incorporation in the hydrogel formulation or indirectly via immersing the final product in a TA solution. In general, TA is a natural bioactive molecule with diverse potential for engineering biomedical hydrogels.

Seaweed Phenolics as Natural Antioxidants, Aquafeed Additives, Veterinary Treatments and Cross-Linkers for Microencapsulation

Driven by consumer demand and government policies, synthetic additives in aquafeed require substitution with sustainable and natural alternatives. Seaweeds have been shown to be a sustainable marine source of novel bioactive phenolic compounds that can be used in food, animal and aqua feeds, or microencapsulation applications. For example, phlorotannins are a structurally unique polymeric phenolic group exclusively found in brown seaweed that act through multiple antioxidant mechanisms. Seaweed phenolics show high affinities for binding proteins via covalent and non-covalent bonds and can have specific bioactivities due to their structures and associated physicochemical properties. Their ability to act as protein cross-linkers means they can be used to enhance the rheological and mechanical properties of food-grade delivery systems, such as microencapsulation, which is a new area of investigation illustrating the versatility of seaweed phenolics. Here we review how seaweed phenolics can be used in a range of applications, with reference to their bioactivity and structural properties.

Tannic Acid-Aminated Sugar Beet Pectin Nanoparticles as a Stabilizer of High-Internal-Phase Pickering Emulsions

Pickering stabilizers with additional antioxidant, photostabilizing, and metal-chelating properties are suitable for structuring multifunctional Pickering emulsion systems. Tannic acid (TA) is a potential material which when adsorbed onto the interface may impart antioxidant, UV-light-shielding, and chelating properties to Pickering stabilizers. Herein, we report a type of TA polyelectrolyte nanoparticles (NPs) fabricated following a complexation between TA and aminated sugar beet pectin (SBP-NH₂). This study is geared toward investigating the performance of TA/SBP-NH₂ NPs in stabilizing Pickering emulsions and protecting β-carotene from degradation. TA/SBP-NH₂ NPs formed under optimum conditions had a mean diameter of 82 nm with a sphere-like shape. Because of their favorable surface wettability (91.2°), TA/SBP-NH₂ NPs promoted formation of the low-, medium-, and high-internal-phase Pickering emulsions (HIPEs) in an oil volume fraction (φ)-dependent manner; the TA/SBP-NH₂ NP-stabilized HIPE demonstrated viscoelastic properties increasing with the increasing concentration (c) of nanoparticles. Due to the excellent storage stability and UV light-absorbing capacity, the photostability of β-carotene was significantly improved by a TA/SBP-NH₂ NP-stabilized HIPE (φ = 0.75; c = 3 mg/mL). Altogether, this study highlights that TA/SBP-NH₂ NPs have potential applications in structuring Pickering emulsions with improved protective effects on loaded lipophilic compounds.

Polysaccharides improved the viscoelasticity, microstructure, and physical stability of ovalbumin-ferulic acid complex stabilized emulsion

This study explored the mechanism underlying the interactions between polysaccharides and ovalbumin-ferulic acid (OVA-FA) and the effect of polysaccharides on OVA-FA-stabilized emulsions. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to study the polysaccharide OVA-FA interactions mechanism and to resolve the changes in the protein secondary structure and crystal structure. OVA-FA-polysaccharide-stabilized emulsions were studied using confocal laser scanning microscopy (CLSM), and their rheological properties and stability were determined. The results showed that the non-covalent interactions between polysaccharides and OVA-FA led to an increase in the β-sheet content of OVA and a decrease in the α-helix and random coil contents. The stability of the OVA-FA-polysaccharide-stabilized emulsions was better compared with that of the OVA-FA-stabilized emulsions. By comparing the different OVA-FA-polysaccharide-stabilized emulsions, we observed that OVA-FA-agar did not stabilize the emulsion well, while the OVA-FA-SA- and OVA-FA-KC-stabilized emulsions had good elasticity, and the microstructure and storage stability of the OVA-FA-KC-stabilized emulsion were better. Our findings provide a new perspective for the application of OVA-FA-KC in complex food emulsions.

Complexation of Anthocyanin-Bound Blackcurrant Pectin and Whey Protein: Effect of pH and Heat Treatment

A complexation study between blackcurrant pectin (BCP) and whey protein (WP) was carried out to investigate the impact of bound anthocyanins on pectin−protein interactions. The effects of pH (3.5 and 4.5), heating (85 °C, 15 min), and heating sequence (mixed-heated or heated-mixed) were studied. The pH influenced the color, turbidity, particle size, and zeta-potential of the mixtures, but its impact was mainly significant when heating was introduced. Heating increased the amount of BCP in the complexes—especially at pH 3.5, where 88% w/w of the initial pectin was found in the sedimented (insoluble) fraction. Based on phase-separation measurements, the mixed-heated system at pH 4.5 displayed greater stability than at pH 3.5. Heating sequence was essential in preventing destabilization of the systems; mixing of components before heating produced a more stable system with small complexes (<300 nm) and relatively low polydispersity. However, heating WP before mixing with BCP prompted protein aggregation—producing large complexes (>400 nm) and worsening the destabilization. Peak shifts and emergence (800−1200 cm−1) in infrared spectra confirmed that BCP and WP functional groups were altered after mixing and heating via electrostatic, hydrophobic, and hydrogen bonding interactions. This study demonstrated that appropriate processing conditions can positively impact anthocyanin-bound pectin−protein interactions.

The non-covalent interactions between whey protein and various food functional ingredients

In daily diet, Whey protein (WP) is often coexisted with various Food functional ingredients (FFI) such as proteins, polyphenols, polysaccharides and vitamins, which inevitably affect or interact with each other. Generally speaking, they may be interact by two different mechanisms: non-covalent and covalent interactions, of which the former is more common. We reviewed the non-covalent interactions between WP and various FFI, explained the effect of each WP-FFI interaction, and provided possible applications of WP-FFI complex in the food industry. The biological activity, physical and chemical stability of FFI, and the structure and functionalities of WP were enhanced through the non-covalent interactions. The development of non-covalent interactions between WP and FFI provides opportunities for the design of new ingredients and biopolymer complex, which can be applied in different fields. Future research will further focus on the influence of external or environmental factors in the food system and processing methods on interactions.

Value-Added Crackers Enriched with Red Onion Skin Anthocyanins Entrapped in Different Combinations of Wall Materials

The objective of this study was to encapsulate anthocyanins from red onion skins into different biopolymeric matrices as a way to develop powders with multifunctional activities. Two different variants of powders were obtained using a combination of gelation and freeze-drying techniques and characterized by encapsulation efficiency, antioxidant activity, phytochemical content, and color. Stability during storage and the bioavailability of anthocyanins in the in vitro simulated digestion were also examined. Powder V2, with a higher concentration of polysaccharides than V1, allowed a better encapsulation efficiency (90.53 ± 0.29%) and good stability during storage. Both variants had a high content of phytochemicals and antioxidant activity. In vitro investigations proved that an increased polysaccharides concentration offers the best protection for anthocyanins. Thus, a controlled release of the anthocyanins in the intestinal medium was achieved. The powder with the highest encapsulation efficiency was added to crackers, followed by phytochemical characterization to assess its potential added value. The addition of the micro-particles improved the functional characteristics such as antioxidant activity, showing its suitability for the development of bakery products. The attained results may bring implicit benefits to consumers, who can benefit from improved bioactive concentrations in foodstuffs, with significant health benefits.

The complex of whey protein and pectin: Interactions, functional properties and applications in food colloidal systems - A review

This review describes the mechanism of non-covalent/covalent interaction of whey protein-pectin (WPP) complexes, including electrostatic interaction, steric hindrance, cross-linking and Maillard reaction. The interaction between whey protein and pectin determines the form of the complex in the system, i.e. co-dissolution, precipitation, separation, complex coacervation and compounding. The interaction of WPP is affected by environmental conditions and its own properties, including several factors such as pH, polymer concentration and ratio, temperature, and ionic strength. In addition, the functional properties of WPP complexes are discussed through illustrative examples. The complexes with good emulsification, heat stability, gelling properties and biological activity have promising application prospects. WPP complexes have been widely studied for application in food colloidal systems, including protein beverages, delivery systems for bioactive substances, fat substitutes and food preservation films/coatings. The understanding of the interaction and functional properties of WPP complexes provides theoretical support for the improvement and design of new food colloidal systems.

Reactivity of flavanols: Their fate in physical food processing and recent advances in their analysis by depolymerization

Flavanols, a subgroup of polyphenols, are secondary metabolites with antioxidant properties naturally produced in various plants (e.g., green tea, cocoa, grapes, and apples); they are a major polyphenol class in human foods and beverages, and have recognized effect on maintaining human health. Therefore, it is necessary to evaluate their changes (i.e., oxidation, polymerization, degradation, and epimerization) during various physical processing (i.e., heating, drying, mechanical shearing, high-pressure, ultrasound, and radiation) to improve the nutritional value of food products. However, the roles of flavanols, in particular for their polymerized forms, are often underestimated, for a large part because of analytical challenges: they are difficult to extract quantitatively, and their quantification demands chemical reactions. This review examines the existing data on the effects of different physical processing techniques on the content of flavanols and highlights the changes in epimerization and degree of polymerization, as well as some of the latest acidolysis methods for proanthocyanidin characterization and quantification. More and more evidence show that physical processing can affect content but also modify the structure of flavanols by promoting a series of internal reactions. The most important reactivity of flavanols in processing includes oxidative coupling and rearrangements, chain cleavage, structural rearrangements (e.g., polymerization, degradation, and epimerization), and addition to other macromolecules, that is, proteins and polysaccharides. Some acidolysis methods for the analysis of polymeric proanthocyanidins have been updated, which has contributed to complete analysis of proanthocyanidin structures in particular regarding their proportion of A-type proanthocyanidins and their degree of polymerization in various plants. However, future research is also needed to better extract and characterize high-polymer proanthocyanidins, whether in their native or modified forms.

Towards the systematic design of multilayer O/W emulsions with tannic acid as an interfacial antioxidant

This work discusses the possibility of designing multilayer oil-in-water emulsions to introduce the maximum possible amount of an antioxidant at the droplet interfaces for the optimal protection of a linseed oil core against oxidation, using a systematic three-step colloidal procedure. An antioxidant (here Tannic Acid - TA) is chosen and its interactions with a primary emulsifier (here Bovine Serum Albumin - BSA) and several polysaccharides are first examined in solution using turbidity measurements. As a second step, LbL deposition on solid surfaces is used to determine which of the polysaccharides to combine with BSA and tannic acid in a multilayer system to ensure maximum presence of tannic acid in the films. From UV-vis and polarization modulation infrared reflection-absorption (PM-IRRAS) spectroscopic measurements it is suggested that the best components to use in a multilayer emulsion droplet, together with BSA and TA, are chitosan and pectin. BSA, chitosan and pectin are subsequently used for the formation of three-layer linseed oil emulsions, and tannic acid is introduced into any of the three layers as an antioxidant. The effect of the exact placement of tannic acid on the oxidative stabilization of linseed oil is assessed by monitoring the fluorescence of Nile red, dissolved in the oil droplets, under the attack of radicals generated in the aqueous phase of the emulsion. From the results it appears that the three-stage procedure presented here can serve to identify successful combinations of interfacial components of multilayer emulsions. It is also concluded that the exact interfacial placement of the antioxidant plays an important role in the oxidative stabilization of the valuable oil core.

Whey Protein Isolate Microgel Properties Tuned by Crosslinking with Organic Acids to Achieve Stabilization of Pickering Emulsions

Whey protein isolate (WPI) can be used effectively to produce food-grade particles for stabilizing Pickering emulsions. In the present study, crosslinking of WPI microgels using organic acids (tannic and citric acids) is proposed to improve their functionality in emulsions containing roasted coffee oil. It was demonstrated that crosslinking of WPI by organic acids reduces the microgels’ size from ≈1850 nm to 185 nm and increases their contact angle compared to conventional WPI microgels, achieving values as high as 60°. This led to the higher physical stability of Pickering emulsions: the higher contact angle and smaller particle size of acid-crosslinked microgels contribute to the formation of a thinner layer of particles on the oil/water (O/W) interface that is located mostly in the water phase, thus forming an effective barrier against droplet coalescence. Particularly, emulsions stabilized by tannic acid-crosslinked WPI microgels presented neither creaming nor sedimentation up to 7 days of storage. The present work demonstrates that the functionality of these crosslinked WPI microgels can be tweaked considerably, which is an asset compared to other food-grade particles that mostly need to be used as such to comply with the clean-label policy. In addition, the applications of these particles for an emulsion are much more diverse as of the starting material.

Molecular interaction between pectin and catechin/procyanidin in simulative juice model: Insights from spectroscopic, morphology, and antioxidant activity

The interactions between polysaccharides and phenolics in foods affect their physicochemical properties and bioactivity. Pectin and catechin/procyanidin present in plants ubiquitously and attracting more attentions for the potential health benefits. This work investigates the interactions between high methoxyl pectin and catechin/procyanidin in a simulative juice model using multiple microscopic and spectroscopic approaches and their influences on the antioxidant activity of phenolics were evaluated in the Caco-2 cells model. The results showed that pectin with either of phenolic compunds exhibited lower transmittance, zeta potential, viscosity, and larger particle size than it alone. The morphology of pectin complexes with either of phenolics under experimental conditions (pH = 3.5) was observed. The ΔH° (-6.821 kJ mol^-1 ) and ΔS° (6.357×10^-2  kJ mol^-1 ) indicated that pectin interacts with procyanidin via electrostatic interaction, whereas hydrophobic interaction was the dominant drive force between pectin and catechin (ΔH° = 1.422 kJ mol^-1 ; ΔS° = 13.048 × 10^-2  kJ mol^-1 ). The antioxidant activities of catechin/procyanidin decreased while binding with pectin based on indexes of glutathione peroxidase, total superoxide dismutase, total antioxidant capacity, and malondialdehyde. PRACTICAL APPLICATION: The findings of this work indicated that the physicochemical property of pectin and the antioxidant activity of catechin/procyanidin were influenced by the interactions between pectin and catechin/procyanidin in a simulative food system. This study provides insights into the molecular interactions between pectin and phenolics in a simulative food system.

Influence of food matrix and food processing on the chemical interaction and bioaccessibility of dietary phytochemicals: A review

Consumption of phytochemicals-rich foods shows the health effect on some chronic diseases. However, the bioaccessibility of these phytochemicals is extremely low, and they are often consumed in the diet along with the food matrix. The food matrix can be described as a complex assembly of various physical and chemical interactions that take place between the compounds present in the food. Some studies indicated that the physiological response and the health benefits of phytochemicals are resultant in these interactions. Some food substrates inhibit the absorption of phytochemicals via this interaction. Moreover, processing technologies have been developed to facilitate the release and/or to increase the accessibility of phytochemicals in plants or breakdown of the food matrix. Food processing processes may disrupt the activity of phytochemicals or reduce bioaccessibility. Enhancement of functional and sensorial attributes of phytochemicals in the daily diet may be achieved by modifying the food matrix and food processing in appropriate ways. Therefore, this review concisely elaborated on the mechanism and the influence of food matrix in different parts of the digestive tract in the human body, the chemical interaction between phytochemicals and other compounds in a food matrix, and the various food processing technologies on the bioaccessibility and chemical interaction of dietary phytochemicals. Moreover, the enhancing of phytochemical bioaccessibility through food matrix design and the positive/negative of food processing for dietary phytochemicals was also discussed in this study.

Effects of tea polyphenols on physicochemical and antioxidative properties of whey protein coating

Effects of tea polyphenols (TP) incorporation on physicochemical and antioxidative properties of whey protein isolate (WPI) coating were studied. Two WPI coating solutions were prepared by heating WPI solutions (pH 8, 90 °C) for 30 min and then TP was incorporated. TP addition could increase the negative zeta potential of 5% solution. The surface hydrophobicity index of both solutions was increased and intrinsic fluorescence intensity decreased greatly after addition of TP. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis (2 ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging capacities of both solutions increased with increasing TP. Compared with apple pieces coated with whey protein only, those with TP containing whey protein coatings showed lower browning index and slight changes in weight loss during 24 h storage. Data indicated that TP could influence the physicochemical properties and improve the antioxidant activity of WPI coating solutions and can be used to retard the enzymatic browning of fruit during storage.