Colloidal complexation of zein hydrolysate with tannic acid: Constructing peptides-based nanoemulsions for alga oil delivery

Physicochemical and emulsifying properties of mussel water-soluble proteins as affected by lecithin concentration

The effects of lecithin addition at different concentrations (0-2.0%) on the physicochemical and emulsifying properties of mussel water-soluble proteins (MWP) were investigated. In solution system, low lecithin concentration (0.5%-1.0%) induced the aggregation and increased turbidity of composite particles. Lecithin addition caused changes in secondary structure and induced partial unfolding of MWP. Hydrophobic interactions between MWP and lecithin may contribute to the exposure of chromophores and hydrophobic groups of MWP. The interfacial tension decreased with lecithin addition. However, at a high lecithin concentration (1.5%-2.0%), the degree of aggregation and state of unfolding alleviated due to competitive adsorption. In emulsion system, with the low concentration of lecithin addition (0.5%-1.0%), droplet size and surface charge of emulsion decreased. The emulsion activity index, emulsion stability index, percentage of adsorbed protein increased. Both creaming stability and viscoelastic properties improved. At an intermediate lecithin concentration (1.0%), the emulsion showed the highest physical stability, while further addition of lecithin caused a slight deterioration in emulsifying properties. Overall, these results indicated the possibility that the lecithin-MWP mixed emulsifiers can be used to obtain emulsions with desirable properties.

Improvement in Entrapment Efficiency and In Vitro Digestion Stability of Lutein by Zein Nanocarriers with Pepsin Hydrolysis

Zein is one of the popular bioactive carriers and play critical roles in the promotion of stability, absorption, and utilization of the nutrients and bioactive ingredients. The application of zein delivery systems for the encapsulation of bioactive ingredients has recently gained increasing interest. The aim of this work was to modify zein by pepsin and prepare the lutein-loaded zein nanoparticle (LZN) and the lutein-loaded zein hydrolysate nanoparticle (LZHN), respectively. The effects of zein hydrolysation on entrapment efficiency and in vitro digestion stability of lutein were also evaluated in this study. Hydrolysation of zein by the pepsin has important effects on lutein embedding. The optimal hydrolysis conditions, including the pepsin concentration (1.5%), temperature (55°C), and time (4 h), enhanced the entrapment efficiency (EE) of lutein by 93.82 ± 2.82% as compared to 85.18 ± 3.28% of the untreated zein, respectively. In contrast to LZN, LZHN had better structural characteristics, the average particle size decreases from 158.40 ± 3.22 nm to 112.2 ± 1.56 nm, and LZHN showed better dispersivity and zeta potential. The stability and release assays in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) showed that hydrolyzed zein nanocarriers by pepsin improved the digestion stability and promoted the release of lutein under gastrointestinal digestive conditions. These results suggest that hydrolyzed zein with pepsin may act as an effective carrier for lutein delivery and shows many potential advantages compared with the zein.

Evaluation of antioxidant modification on the functional and structural properties of EWP conjugates

The aim of this present study was to improve the oxidative stability of egg white protein (EWP) through catechin (CT) and epigallocatechin gallate (EGCG) covalent modification via an alkaline method at pH 9.0. Effects of CT and EGCG conjugation on the antioxidant activities, physicochemical and structural properties of EWP were comprehensively studied. The results indicated that CT and EGCG modification altered the isoelectric point value of EWP to lower pH, thus the solubility of EWP conjugates at pH 3.8 decreased, especially after EGCG conjugation. In addition, the antioxidant activities of EWP–CT and EWP–EGCG conjugates were 2.88 and 3.52 fold (2-diphenyl-1-picrylhydrazyl radical scavenging activities), 2.60 and 7.91 fold (ferric reducing powers) higher than that of the unmodified EWP. Moreover, the CT or EGCG conjugation resulted in an increase in alpha-helix formation with a decrease in the β-sheet formation, indicating that the secondary structure of EWP became more compact after CT or EGCG modification, and Trp and Tyr residues were involved into the conjugation reaction of EWP with CT or EGCG. Furthermore, CT and EGCG conjugation obviously improved the emulsifying stability of EWP, due to the improvement of the antioxidant activity after being modified by the CT or EGCG. In conclusion, CT or EGCG conjugation with EWP via an alkaline method was an effective way to improve the utilization value of EWP.

The aim of this present study was to improve the oxidative stability of egg white protein (EWP) through catechin (CT) and epigallocatechin gallate (EGCG) covalent modification via an alkaline method at pH 9.0.

Food-Grade Nanoemulsions: Preparation, Stability and Application in Encapsulation of Bioactive Compounds

Nanoemulsions have attracted significant attention in food fields and can increase the functionality of the bioactive compounds contained within them. In this paper, the preparation methods, including low-energy and high-energy methods, were first reviewed. Second, the physical and chemical destabilization mechanisms of nanoemulsions, such as gravitational separation (creaming or sedimentation), flocculation, coalescence, Ostwald ripening, lipid oxidation and so on, were reviewed. Then, the impact of different stabilizers, including emulsifiers, weighting agents, texture modifiers (thickening agents and gelling agents), ripening inhibitors, antioxidants and chelating agents, on the physicochemical stability of nanoemulsions were discussed. Finally, the applications of nanoemulsions for the delivery of functional ingredients, including bioactive lipids, essential oil, flavor compounds, vitamins, phenolic compounds and carotenoids, were summarized. This review can provide some reference for the selection of preparation methods and stabilizers that will improve performance in nanoemulsion-based products and expand their usage.

Oxidized Dextran as a Macromolecular Crosslinker Stabilizes the Zein/Caseinate Nanocomplex for the Potential Oral Delivery of Curcumin

In this study, we prepared complex nanoparticles from a combination of two proteins and one polysaccharide for the encapsulation and delivery of lipophilic bioactive compounds. Two proteins, zein and sodium caseinate (NaCas), provided a hydrophobic core for the encapsulation of a lipophilic compound (curcumin), while a polysaccharide dialdehyde, oxidized dextran, served as the coating material and macromolecular crosslinker to create covalent linkage with two proteins for stabilization purposes. The heating time and crosslinker concentration were optimized to achieve the desirable colloidal stability in simulated gastric and intestinal fluids. Our results suggested that heating time played a more important role than the concentration of oxidized dextran. The optimized complex nanoparticles had a particle size of around 150 nm with a PDI < 0.1 and negative surface charge. Morphological observation by transmission electron microscopy revealed a spherical shape and uniform size distribution. Fourier transform infrared and fluorescence spectroscopies evidenced the formation of Schiff base complex, confirming the validity of covalent crosslinking. Furthermore, the complex nanoparticles demonstrated superior encapsulation properties for curcumin, showing an efficiency of >90% at 10% loading. A rather slow kinetic release profile of curcumin from complex nanoparticles was observed under simulated gastrointestinal conditions. The complex nanoparticles prepared from zein, NaCas, and oxidized dextran hold promising potential for the oral delivery of lipophilic bioactive compounds.

The Effect of (-)-Epigallocatechin-3-Gallate Non-Covalent Interaction with the Glycosylated Protein on the Emulsion Property

The effect of (−)-epigallocatechin-3-gallate (EGCG) on protein structure and emulsion properties of glycosylated black bean protein isolate (BBPI-G) were studied and compared to native black bean protein isolate (BBPI). The binding affinity of BBPI and BBPI-G with EGCG belonged to non-covalent interaction, which was determined by fluorescence quenching. EGCG attachment caused more disordered protein conformation, leading to a higher emulsification property. Among the different EGCG concentrations (0.10, 0.25, 0.50 mg/mL), the result revealed that the highest level of the emulsification property was obtained with 0.25 mg/mL EGCG. Therefore, the BBPI-EGCG and BBPI-G-EGCG prepared by 0.25 mg/mL EGCG were selected to fabricate oil-in-water (O/W) emulsions. After the addition of EGCG, the mean particle size of emulsions decreased with the increasing absolute value of zeta-potential, and more compact interfacial film was formed due to the higher percentage of interfacial protein adsorption (AP%). Meanwhile, EGCG also significantly reduced the lipid oxidation of emulsions.

Nano-encapsulation of curcumin using soy protein hydrolysates - tannic acid complexes regulated by photocatalysis: a study on the storage stability and in vitro release

Purpose: To evaluate the feasibility of soy protein hydrolysates (SPH)-tannic acid (TA) complex nanoparticle obtained by photocatalysis (SPH-T (P)) to construct curcumin (Cur) delivery vehicles. Methods: The interaction behaviour of SPH-T (P) was investigated using Fourier transform infra-red, X-ray diffraction and differential scanning calorimeter analyzes. Formation and stability of the complexes were characterised by particle size, morphology, zeta potential, and in vitro release. Results: Negatively charged Cur-loaded complex with small size (<100 nm), spherical cluster shape and uniform size distribution were formed through the driving force of electrostatic attraction, followed by hydrogen bonding. The presence of photocatalysis in the complexes significantly improved the storage stability and in vitro sustained release of curcumin by enhancing the hydrogen bonding, hydrophobic effects and π-π stacking interactions between SPH and TA. Conclusion: SPH-T (P) would be a useful and promising delivery vehicle for encapsulating, protecting, and delivering hydrophobic nutraceuticals.

Ultrasound-mediated fucoxanthin rich oil nanoemulsions stabilized by κ-carrageenan: Process optimization, bio-accessibility and cytotoxicity

This work aims to produce and optimize a κ-carrageenan-based nanoemulsion (NE) to encapsulate seaweed oil, which is rich in fucoxanthin (FX), using ultrasound-assisted emulsification. κ-Carrageenan was produced using subcritical water, and seaweed oil was extracted using supercritical carbon dioxide with sunflower oil as the co-solvent. Response surface methodology (RSM) was used to understand the influence of several process parameters such as ultrasound amplitude, time, temperature, and duty cycle to produce an NE. The RSM factor was used to focus on droplet size, polydispersity index, zeta potential, viscosity, antioxidant, FX, encapsulation efficiency, and emulsion stability. Our outcomes suggested that the ultrasound process had a noteworthy influence on the NE. The best conditions to obtain an NE were an ultrasound amplitude of 87 µm, a sonication time of 394 s, a temperature of 60 °C, and a duty cycle of 50%. The resulting NE was studied by UV-Vis, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy, and X-ray diffraction. Moreover, the NE obtained from optimized conditions was checked for fatty acid content, color, oxidative stability, in vitro digestion, bioaccessibility of FX, and cytotoxicity. The results obtained suggest that lower droplet size of the emulsion can improve oxidative stability, in vitro digestion, bioaccessibility of FX, and good cell inhibition against a few cell lines. Therefore, a κ-carrageenan-stabilized NE can be used as a potential delivery system to endorse applications of seaweed oil, which is rich in FX, in functional foods, beverage systems, and pharmaceuticals.

Covalent Interaction between Rice Protein Hydrolysates and Chlorogenic Acid: Improving the Stability of Oil-in-Water Emulsions

Protein hydrolysates, as surfactants, can scavenge radicals, but their poor distributions at the oil-water interface limit their storage stability. Therefore, we studied covalent interaction between rice protein hydrolysates and chlorogenic acid under alkaline conditions to improve the physical and oxidative stability of oil-in-water emulsions. Turbidity and particle size measurements demonstrated the formation of hydrolysates-chlorogenic acid complexes, and their covalent interaction resulted in the decrease and redshift of the fluorescence intensity. The emulsifying activity of the hydrolysates could be effectively improved after the covalent interaction with 0.025% chlorogenic acid. The modified emulsions possessed a notable physical stability according to the least changes in size (0.08 μm) and ζ-potential (3.34 mV) of the emulsion ( P > 0.05). Moreover, the covalent interaction endowed modified emulsions with high oxidative stability to effectively inhibit lipid oxidative deterioration during storage. The adsorption of hydrolysates to the emulsion interface was increased by the adequate addition of chlorogenic acid, which resulted in the oil droplet being surrounded by a thicker interfacial film. The covalent interaction between the protein hydrolysates and chlorogenic acid could be used to construct natural emulsion systems with a higher physical and oxidative stability during storage.

Foaming properties and air-water interfacial behavior of corn protein hydrolyzate-tannic acid complexes

The complexation of corn protein hydrolyzate (CPH) with tannic acid (TA) was utilized to improve the foaming properties of CPH itself, and the air-water interfacial behavior of CPH-TA complex was also investigated. The results showed that the surface hydrophobicity of pure CPH was significantly decreased in bulk solution after the complexation with TA. Compared with pure CPH, the foams stabilized by CPH-TA complex showed higher interfacial thickness between the bubbles, which well explained the better long term stability of the corresponding foams. Therefore, the complexation maintained the good foaming capacity of CPH itself, but considerably increased its foam stability. Moreover, the air-water interfacial behavior study demonstrated that the complexation slightly decreased the interfacial activity of CPH itself, but considerably increased its interfacial viscoelasticity, suggesting more stable of the air-water interface stabilized by CPH-TA complex compared with that stabilized by CPH alone. These findings indicated that foaming properties of the surface active components were closely related with its air-water interfacial behavior. The study suggested that CPH-TA complex could be used as a stabilizer in constructing the peptides-based foams.

Characterization and Mechanisms of Novel Emulsions and Nanoemulsion Gels Stabilized by Edible Cyclodextrin-Based Metal-Organic Frameworks and Glycyrrhizic Acid

In this study, a novel emulsion stabilized by nano-cyclodextrin-based metal-organic frameworks and glycyrrhizic acid (CD-MOF/GA) was successfully fabricated, exhibiting long-term storage stability. The characterization and mechanisms for the emulsion formation with CD-MOF/GA were studied. The phase change of the emulsions from sol to gel could be controlled using different oil fractions and mass ratios of CD-MOF and GA. The rheological results showed that the emulsions were transformed from liquid emulsions to emulsion gels when the oil fractions were higher than 0.3 and the mass ratio of CD-MOF and GA was 1:3. The low-field nuclear magnetic resonance results revealed that the T₂₂ relaxation time of emulsions decreased from 403.702 to 231.013 ms when the oil fractions increased from 0.1 to 0.6, indicating that movable water was converted to constructal water. The emulsions showed good stability, even in high-alkaline pH and high-temperature conditions.

Bioaccessibility and stability of β-carotene encapsulated in plant-based emulsions: impact of emulsifier type and tannic acid

The effect of two plant-based emulsifiers (quillaja saponin, QS and gum arabic, GA) and a polyphenol (tannic acid) on the formation, stability, digestibility, and β-carotene (BC) bioaccessibility of flaxseed oil-in-water emulsions was investigated.

Impact of plant extract on the gastrointestinal fate of nutraceutical-loaded nanoemulsions: phytic acid inhibits lipid digestion but enhances curcumin bioaccessibility

The impact of phytic acid on lipid digestion and curcumin bioaccessibility in oil-in-water nanoemulsions was investigated using a simulated gastrointestinal tract (GIT).

The protective role of tannic acid against possible hepato-nephrotoxicity induced by silver nanoparticles on male rats

Silver nanoparticles (AgNPs) are being used extensively for biomedical purposes regarding to their broad antimicrobial activity, however their toxicity has been addressed in only few studies. In the present study, we aimed to prepare and characterize AgNPs, investigate their adverse effect on liver and kidney functions, and also elucidate the hepato-nephro protective ability of tannic acid in male rats. The obtained results showed that AgNPs caused oxidative stress throughout the induction of thiobarbituric acid-reactive substances (TBARS) and the reduction of the activities of antioxidant enzymes (GST, SOD, CAT, GPx) and the levels of glutathione. Hepatic markers enzymes (AST, ALT, ALP, ACP, LDH and GGT), total bilirubin, urea, creatinine and lipid profile were increased, while hematological parameters were decreased. Histopathological investigations indicated marked degeneration of hepatocytes, endothelial cells of renal which with its role has confirmed the hepatotoxicity and nephrotoxicity induced by AgNPs. The presence of tannic acid along with AgNPs showed obvious improvements in the injured liver and kidney tissues. The protective effect of tannic acid against the toxicity of AgNPs might be due to its antioxidant properties and scavenging abilities against active free radicals.

One-step formation of a double Pickering emulsion via modulation of the oil phase composition

There are two long-standing issues that are holding back the full exploitation of food-based double emulsions: (i) unavailability of large-scale equipment to ensure efficient nondestructive two-step emulsification and (ii) limited food-grade ingredients available to replace polyglycerol polyricinoleate (PGPR) as the primary emulsifier. To overcome these, a facile one-step emulsification strategy was developed to generate a food-grade W/O/W double Pickering emulsion by using corn-peptide-functionalized calcium phosphate (CP-CaP) particles as the emulsifier. It was demonstrated that the wettability of such CP-CaP particles can be tuned through modulation of the oil phase composition. The incorporation of health benefiting ω-3 oils (algal oil) or essential polyunsaturated fatty acids (linoleic acid and linolenic acid) into common vegetable oils leads to the hydrophobization of a fraction of CP-CaP particles through in situ adsorption of the free fatty acids, which provide satisfactory stabilization of both O/W and W/O interfaces, thus generating stable double Pickering emulsions. Moreover, the algal oil-loaded double Pickering emulsions that incorporate water-soluble isoascorbic acid show improvement in both their oxidative stability and flavor properties. This study demonstrated that the edible CP-CaP particle based double Pickering emulsions have promising potential to be applied in the food industry.

Interfacial Antioxidants: A Review of Natural and Synthetic Emulsifiers and Coemulsifiers That Can Inhibit Lipid Oxidation

There has been strong interest in developing effective strategies to inhibit lipid oxidation in emulsified food products due to the need to incorporate oxidatively labile bioactive lipids, such as ω-3 fatty acids, conjugated linoleic acids, or carotenoids. Emulsifiers or coemulsifiers can be utilized to inhibit lipid oxidation in emulsions. Both of these molecular types can adsorb to droplet surfaces and inhibit lipid oxidation, but emulsifiers can also stabilize droplets against aggregation whereas coemulsifiers cannot. There are a host of existing emulsifiers, covalent conjugates, or physical complexes that have the potential to inhibit lipid oxidation by a variety of mechanisms. Existing emulsifiers with antioxidant potential consist of surfactants, phospholipids, proteins, polysaccharides, and colloidal particles. Conjugates and complexes are typically formed by covalently or physically linking together a surface-active molecule with an antioxidant molecule. This article reviews the molecular and physicochemical basis for the surface and antioxidant activities of emulsifiers and coemulsifiers, highlights the important properties of interfacial layers that can be engineered to control lipid oxidation, and outlines different kinds of existing emulsifiers, conjugates, and complexes that can be used to inhibit oxidation.

Inactivation of Soybean Trypsin Inhibitor by Epigallocatechin Gallate: Stopped-Flow/Fluorescence, Thermodynamics, and Docking Studies

Tea is one of the most widely daily consumed beverages all over the world, and it is usually consumed with milk and/or soy milk. However, very few researches have studied the interactions between tea polyphenols (TPs) and soy milk proteins as compared with milk proteins. Here, we reported that epigallocatechin gallate (EGCG), a major component of TPs, can effectively inhibit the inhibitory activity of Kunitz trypsin inhibitor (KTI, a major antinutrient in soy milk). The mechanism of inactivation of KTI by EGCG was investigated by stopped-flow/fluorescence, thermodynamics, and docking studies. The results indicated that EGCG binds KTI via both hydrophobic and hydrophilic interactions with an association constant of 6.62 × 105 M-1 to form a 1:1 complex. Molecular docking showed the participation of amino acids includes three amino acid residues (Asn13, Pro72, and Trp117) near the reactive site of KTI, which may prevent KTI from contacting trypsin and hence inactivate KTI.

The Interaction between Zein and Lecithin in Ethanol-Water Solution and Characterization of Zein-Lecithin Composite Colloidal Nanoparticles

Lecithin, a naturally small molecular surfactant, which is widely used in the food industry, can delay aging, enhance memory, prevent and treat diabetes. The interaction between zein and soy lecithin with different mass ratios (20:1, 10:1, 5:1, 3:1, 2:1, 1:1 and 1:2) in ethanol-water solution and characterisation of zein and lecithin composite colloidal nanoparticles prepared by antisolvent co-precipitation method were investigated. The mean size of zein-lecithin composite colloidal nanoparticles was firstly increased with the rise of lecithin concentration and then siginificantly decreased. The nanoparticles at the zein to lecithin mass ratio of 5:1 had the largest particle size (263 nm), indicating that zein and lecithin formed composite colloidal nanoparticles, which might aggregate due to the enhanced interaction at a higher proportion of lecithin. Continuing to increase lecithin concentration, the zein-lecithin nanoparticles possibly formed a reverse micelle-like or a vesicle-like structure with zein in the core, which prevented the formation of nanoparticle aggregates and decreased the size of composite nanoparticles. The presence of lecithin significantly reduced the ζ-potential of zein-lecithin composite colloidal nanoparticles. The interaction between zein and lecithin enhanced the intensity of the fluorescence emission of zein in ethanol-water solution. The secondary structure of zein was also changed by the addition of lecithin. Differential scanning calorimetry thermograms revealed that the thermal stability of zein-lecithin nanoparticles was enhanced with the rise of lecithin level. The composite nanoparticles were relatively stable to elevated ionic strengths. Possible interaction mechanism between zein and lecithin was proposed. These findings would help further understand the theory of the interaction between the alcohol soluble protein and the natural small molecular surfactant. The composite colloidal nanoparticles formed in this study can broaden the application of zein and be suitable for incorporating water-insoluble bioactive components in functional food and beverage products.

Nanochemistry of Protein-Based Delivery Agents

The past decade has seen an increased interest in the conversion of food proteins into functional biomaterials, including their use for loading and delivery of physiologically active compounds such as nutraceuticals and pharmaceuticals. Proteins possess a competitive advantage over other platforms for the development of nanodelivery systems since they are biocompatible, amphipathic, and widely available. Proteins also have unique molecular structures and diverse functional groups that can be selectively modified to alter encapsulation and release properties. A number of physical and chemical methods have been used for preparing protein nanoformulations, each based on different underlying protein chemistry. This review focuses on the chemistry of the reorganization and/or modification of proteins into functional nanostructures for delivery, from the perspective of their preparation, functionality, stability and physiological behavior.

Inherently antioxidant and antimicrobial tannic acid release from poly(tannic acid) nanoparticles with controllable degradability

From a natural polyphenol, Tannic acid (TA), poly(TA) nanoparticles were readily prepared using a single step approach with three different biocompatible crosslinkers; trimethylolpropane triglycidyl ether (TMPGDE), poly(ethylene glycol) diglycidyl ether (PEGGE), and trisodium trimetaphosphate (STMP). P(TA) particles were obtained with controllable diameters between 400 to 800nm with -25mV surface charge. The effect of synthesis conditions, such as the emulsion medium, pH values of TA solution, and the type of crosslinker, on the shape, size, dispersity, yield, and degradability of poly(Tannic Acid) (p(TA)) nanoparticles was systematically investigated. The hydrolytic degradation amount in physiological pH conditions of 5.4, 7.4, and 9.0 at 37.5°C were found to be in the order TMPGDE<PEGGE<STMP. Furthermore, the degradation amounts of TA from p(TA) nanoparticles can be controlled by the appropriate choice of crosslinker, and the pH of releasing media. The highest TA release, 600mg/g, was obtained for TMPGDE-crosslinked p(TA) particles in intestinal pH conditions (pH 9) over 3 days; whereas, a slow and linear TA release profile over almost 30 days was obtained by using PEGGE-crosslinked p(TA) in body fluid pH conditions (pH 7.4). The total phenol content of p(TA) particles was calculated as 70±1μgmL(-1) for 170μgmL(-1) p(TA), and the trolox equivalent antioxidant capacity was found to be 2027±104mM trolox equivalent g(-1). Moreover, p(TA) nanoparticles demonstrated strong antimicrobial effects against common bacterial strains. More interestingly, with a higher concentration of p(TA) particles, higher blood clotting indices were obtained.