Influence of pH, metal chelator, free radical scavenger and interfacial characteristics on the oxidative stability of β-carotene in conjugated whey protein–pectin stabilised emulsion

Recent advances in the color of aquatic products: Evaluation methods, discoloration mechanism, and protection technologies

Color plays a pivotal role in guiding and assessing the industrial production of aquatic products due to the swift sensory perception of information through vision. This review provides a comprehensive overview of the following four aspects: (a) mechanisms governing natural color formation in aquatic products, (b) factors and mechanisms contributing to the discoloration of aquatic products, (c) cutting-edge methods for color analysis and detection, and (d) current valuable techniques for preserving color quality. The natural color of aquatic products is derived from skin chromatophores, endogenous pigment proteins, and astaxanthin. Discoloration of aquatic products can occur due to lipid oxidation, as well as enzymatic and non-enzymatic browning. Furthermore, this review examines frontier color protective technologies, encompassing physical methods like ultra-high pressure, irradiation, and low-temperature plasma, as well as chemical methods involving natural preservatives. The findings of this study offer significant insights into the development of high-quality aquatic products.

Metal nanoparticles and carbohydrate polymers team up to improve biomedical outcomes

The convergence of carbohydrate polymers and metal nanoparticles (MNPs) holds great promise for biomedical applications. Researchers aim to exploit the capability of carbohydrate matrices to modulate the physicochemical properties of MNPs, promote their therapeutic efficiency, improve targeted drug delivery, and enhance their biocompatibility. Therefore, understanding various attributes of both carbohydrates and MNPs is the key to harnessing them for biomedical applications. The many distinct types of carbohydrate-MNP systems confer unique capabilities for drug delivery, wound healing, tissue engineering, cancer treatment, and even food packaging. Here, we introduce distinct physicochemical/biological properties of carbohydrates and MNPs, and discuss their potentials and shortcomings (alone and in combination) for biomedical applications. We then offer an overview on carbohydrate-MNP systems and how they can be utilized to improve biomedical outcomes. Last but not least, future perspectives toward the application of such systems are highlighted.

Rheological property, β-carotene stability and 3D printing characteristic of whey protein isolate emulsion gels by adding different polysaccharides

Emulsion gels with unique structural and mechanical properties have promising applications in 3D food printing. The purpose of this paper was to investigate the rheological property, β-carotene stability and 3D printing characteristic of whey protein isolate (WPI) emulsion gels by adding guar gum (GG), locust bean gum (LBG), xanthan gum (XG) and gum arabic (GA). The results showed that all samples exhibited shear thinning behavior and elastic characteristic. XG could reduce water mobility and increase WHC of WPI emulsion gel. The disulfide bond was the main chemical molecular force of emulsion gels, and XG significantly increased the hydrophobic interactions. GG and LBG increased gel strength, hardness and gumminess, reduced springiness, cohesiveness and chewiness of emulsion gels. GG sample had the best printing performance, more uniform network structure and better stability of β-carotene. This study provided a theoretical basis for 3D printing functional food.

Behavior of protein-polysaccharide conjugate-stabilized food emulsions under various destabilization conditions

The sensitivity of protein-stabilized emulsions to flocculation, coalescence, and phase separation under destabilization conditions (i.e., heating, aging, pH, ionic strength, and freeze-thawing) may limit the widespread use of proteins as effective emulsifiers. Therefore, there is a great interest in modulating and improving the technological functionality of food proteins by conjugating them with polysaccharides, through the Maillard reaction. The present review article highlights the current approaches of protein-polysaccharide conjugate formation, their interfacial properties, and the behavior of protein-polysaccharide conjugate stabilized emulsions under various destabilization conditions, including long-term storage, heating and freeze-thawing treatments, acidic conditions, high ionic strength, and oxidation. Protein-polysaccharide conjugates are capable of forming a thick and cohesive macromolecular layer around oil droplets in food emulsions and stabilizing them against flocculation and coalescence under unfavorable conditions, through steric and electrostatic repulsion. The protein-polysaccharide conjugates could be therefore industrially used to design emulsion-based functional foods with high physicochemical stability.

Recent Trends in Improving the Oxidative Stability of Oil-Based Food Products by Inhibiting Oxidation at the Interfacial Region

In recent years, new approaches have been developed to limit the oxidation of oil-based food products by inhibiting peroxidation at the interfacial region. This review article describes and discusses these particular approaches. In bulk oils, modifying the polarity of antioxidants by chemical methods (e.g., esterifying antioxidants with fatty alcohol or fatty acids) and combining antioxidants with surfactants with low hydrophilic–lipophilic balance value (e.g., lecithin and polyglycerol polyricinoleate) can be effective strategies for inhibiting peroxidation. Compared to monolayer emulsions, a thick interfacial layer in multilayer emulsions and Pickering emulsions can act as a physical barrier. Meanwhile, high viscosity of the water phase in emulsion gels tends to hinder the diffusion of pro-oxidants into the interfacial region. Furthermore, applying surface-active substances with antioxidant properties (such as proteins, peptides, polysaccharides, and complexes of protein-polysaccharide, protein-polyphenol, protein-saponin, and protein-polysaccharide-polyphenol) that adsorb at the interfacial area is another novel method for enhancing oil-in-water emulsion oxidative stability. Furthermore, localizing antioxidants at the interfacial region through lipophilization of hydrophilic antioxidants, conjugating antioxidants with surfactants, or entrapping antioxidants into Pickering particles can be considered new strategies for reducing the emulsion peroxidation.

Effects of Radiation on Cross-Linking Reaction, Microstructure, and Microbiological Properties of Whey Protein-Based Tissue Adhesive Development

Whey proteins are mainly a group of small globular proteins. Their structures can be modified by physical, chemical, and other means to improve their functionality. The objectives of this study are to investigate the effect of radiation on protein−protein interaction, microstructure, and microbiological properties of whey protein−water solutions for a novel biomaterial tissue adhesive. Whey protein isolate solutions (10%, 27%, 30%, 33%, and 36% protein) were treated by different intensities (10−35 kGy) of gamma radiation. The protein solutions were analyzed for viscosity, turbidity, soluble nitrogen, total plate count, and yeast and mold counts. The interactions between whey proteins were also analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and scanning electron microscopy. The viscosity of protein solution (27%, w/w) was increased by the treatment of gamma radiation and by the storage at 23 °C. The 35 kGy intensity irradiated soluble nitrogen (10%, w/w) was reduced to about half of the sample treated by 0 kGy gamma radiation. The effects of gamma radiation and storage time can significantly increase the viscosity of whey protein solutions (p < 0.05). Radiation treatment had significant impact on soluble nitrogen of whey protein solutions (p < 0.05). SDS-PAGE results show that the extent of oligomerization of whey protein isolate solutions are increased by the enhancement in gamma radiation intensity. Photographs of SEM also indicate that protein−protein interactions are induced by gamma radiation in the model system. Consistent with above results, the bonding strength increases by the addition of extent of gamma radiation and the concentration of glutaraldehyde. Our results revealed that the combination of gamma-irradiated whey protein isolate solutions and glutaraldehyde can be used as a novel biomaterial tissue adhesive.

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.

Physicochemical stability and gastrointestinal fate of β-carotene-loaded oil-in-water emulsions stabilized by whey protein isolate-low acyl gellan gum conjugates

This study aimed to examine the effect of whey protein isolate-low acyl gellan gum (WPI-GG) conjugate on the physicochemical properties and digestibility of β-carotene-loaded oil-in-water emulsions. The WPI-GG conjugate-stabilized emulsions had lower droplet sizes with more homogenous distribution, more negative surface charge, and higher interfacial protein concentration and viscosity, compared to those stabilized by WPI-GG mixture and WPI. The emulsion droplets coated by the conjugate were also generally more stable to environmental stresses (i.e., storage, pH changes, ionic strength, freeze-thaw cycles, and thermal treatment) along with higher β-carotene retention than other systems. The stability to droplet aggregation during in vitro digestion was remarkably increased for the conjugate-stabilized emulsion. However, the β-carotene bioaccessibility was significantly affected when the conjugate was used to stabilize the emulsions, likely due to the thick interfacial layer, high viscosity, and negative charge of the corresponding emulsions that could inhibit droplet digestion and mixed micelle formation.

Pectin-peptide complexes ameliorated physicochemical stabilities and in vitro digestion abilities of β-carotene loaded emulsions

To improve the stabilities of low methoxy pectin (LMP) stabilized O/W emulsions for the delivery of bioactive substances, LMP was firstly modified with soy peptide (SP), corn peptide (CP) and whey protein peptide (WPP), respectively, by using dry-heat method, then the properties of LMP-peptide complexes stabilized O/W emulsions were characterized and the in vitro digestion of emulsions with β-carotene was test to evaluate the potential applications. LMP-peptide complexes were formed by covalent bonds according to FT-IR spectroscopy. Compared to LMP stabilized emulsions, LMP-peptide complexes stabilized emulsions had smaller droplet sizes and higher stabilities in the changed pH value, temperature and ionic strength. Based on the results of in vitro digestion tests, LMP-SP and LMP-WPP obtained by incubating LMP with peptides at 60 °C for 12 h at the weight ratio of 4:1 were more suitable for the preparation of O/W emulsions to deliver camellia oil and β-carotene.

Emulsifying properties of a ferulic acid-grafted curdlan conjugate and its contribution to the chemical stability of β-carotene

A biopolymer-polyphenol conjugate-stabilized oil-in-water emulsion system was established to improve the chemical stability and bioaccessibility of β-carotene (BC). In this study, the emulsifying properties and contribution of a ferulic acid-grafted curdlan conjugate (Cur-D-g-FA) to the chemical stability of BC were investigated. Results showed that the emulsification ability of emulsions stabilized by Cur-D-g-FA remarkably increased with an increasing concentration from 0.05% to 0.8% (w/v) along with decreasing average droplet sizes, negatively charged zeta potentials, and uniform size distributions. The emulsions stabilized by 0.8% Cur-D-g-FA exhibited pronounced shear thinning and solid-like elastic properties as well as satisfactory oxidation stability. The emulsions stabilized by 0.8% Cur-D-g-FA had excellent ability to improve the chemical stability of BC when exposed to different environmental stresses and resulted in the favorable bioaccessibility of BC in vitro. The results prove that Cur-D-g-FA as a promising stabilizer has great potential to protect liposoluble nutrients in food-grade emulsion-delivery systems.

Influence of Rosemary Extract Addition in Different Phases on the Oxidation of Lutein and WPI in WPI-Stabilized Lutein Emulsions

The aim was to investigate rosemary extract with different addition methods affecting the physicochemical stability of WPI-coated lutein emulsions and examine the correlations between lutein degradation and WPI oxidation during storage. First, lutein emulsions containing different concentrations of rosemary extract in the oil phase were prepared. Second, lutein emulsions containing rosemary extract in the oil phase or water phase were studied along with the kinetic reaction of lutein degradation. Moreover, the impact of rosemary extract on the oxidation of WPI and their products was also determined. It was noticed that rosemary extract at 0.05 wt.% exhibited the best protection of lutein. According to the kinetics analysis of lutein degradation, the direct addition of rosemary extract in the oil phase was more suitable for retarding the degradation of lutein in emulsion than the addition in the aqueous phase due to it being partitioned at the interface. Meanwhile, it was revealed that the addition of rosemary extract in the water phase exhibited better inhibition of the WPI oxidation than addition in the oil phase. The understanding of the association and driving forces of rosemary extract in emulsion systems may be useful for the application of rosemary extract in multicomponent food systems.

Impact of antioxidant on the stability of β-carotene in model beverage emulsions: Role of emulsion interfacial membrane

The effect of the thickness and density of droplet interfacial membrane on the chemical stability of β-carotene in emulsions was investigated, and its impact on the effectiveness of oil-soluble antioxidants to retard β-carotene degradation was examined. β-Carotene was incorporated into the emulsions stabilized by PEGylated emulsifiers having various-sized hydrophilic groups. In the presence of oxidative stresses (pH, iron ions, and radicals in this study), it was observed that the interfacial thickness was relevant to the stability of β-carotene encapsulated into emulsion droplets. Particularly, iron-mediated carotene degradation was effectively retarded in the emulsions having a thin interfacial membrane than ones with a thick interfacial membrane. The interfacial denseness also affected β-carotene stability but its ability to retard β-carotene degradation was influenced by the interfacial thickness. Although β-carotene degradation rate decreased upon the addition of oil-soluble antioxidants, its antioxidant activity depended on what prooxidant promoted the degradation of β-carotene in the emulsions.

Stability and in vitro digestibility of beta-carotene in nanoemulsions fabricated with different carrier oils

Beta-carotene, the main dietary source of provitamin A, is required for maintaining optimum human health. The bioaccessibility of beta-carotene can be greatly improved when ingested with fat. Therefore, the aim of the current study was to select proper oils (palm oil, coconut oil, fish oil, and corn oil) as a carrier to form stable nanoemulsion that can effectively enhance the bioaccessibility of beta-carotene. The nanoemulsion was formulated with 90% (v/v) aqueous solution (2% whey protein isolate, WPI, w/v) and 10% (v/v) dispersed oil. The in vitro digestion experiment of nanoemulsions showed that the bioaccessibility of beta-carotene was as followed in order: palm oil = corn oil > fish oil > coconut oil (p < 0.05). The particle size of the nanoemulsion (initial particle size = 168-185 nm) was below 200 nm during 42 days' storage at 25°C. The retention rates of beta-carotene in nanoemulsions were 69.36%, 63.81%, 49.58%, and 54.91% with palm oil, coconut oil, fish oil, and corn oil, respectively. However, the particle size of the nanoemulsion increased significantly in the accelerated experiment at 55°C (p < 0.05), in which the retention rates of beta-carotene were 48.56%, 43.41%, 29.35%, and 33.60% with palm oil, coconut oil, fish oil, and corn oil, respectively. From above, we conclude that WPI-stabilized beta-carotene nanoemulsion with palm oil as the carrier is the most suitable system to increase bioaccessibility and stability of lipid-soluble bioactive compounds such as beta-carotene.

Physicochemical Properties and Chemical Stability of β-Carotene Bilayer Emulsion Coated with Bovine Serum Albumin and Arabic Gum Compared to Monolayer Emulsions

β-carotene is a lipophilic micronutrient that is considered beneficial to human health. However, there are some limitations in utilizing β-carotene in functional foods or dietary supplements currently because of its poor water dispersibility and chemical stability. A new type of β-carotene bilayer emulsion delivery system was prepared by a layer-by-layer electrostatic deposition technique, for which were chosen bovine serum albumin (BSA) as the inner emulsifier and Arabic gum (GA) as the outer emulsifier. The physicochemical properties of bilayer emulsions were mainly characterized by droplet size distribution, zeta potential, rheological behavior, Creaming Index (CI), and encapsulation ratio of β-carotene. Besides this, the effects of processing conditions (pH, thermal treatment, UV radiation, strong oxidant) and storage time on the chemical stability of bilayer emulsions were also evaluated. The bilayer emulsion had a small droplet size (221.27 ± 5.17 nm) and distribution (PDI = 0.23 ± 0.02), strong zeta potential (-30.37 ± 0.71 mV), good rheological behavior (with the highest viscosity that could reduce the possibility of flocculation) and physical stability (CI = 0), high β-carotene encapsulation ratio (94.35 ± 0.71%), and low interfacial tension (40.81 ± 0.86 mN/m). It also obtained better chemical stability under different environmental stresses when compared with monolayer emulsions studied, because it had a dense and thick bilayer structure.

Emulsion design for the delivery of β-carotene in complex food systems

β-Carotene has been widely investigated both in the industry and academia, due to its unique bioactive attributes as an antioxidant and pro-vitamin A. Many attempts were made to design delivery systems for β-carotene to improve its dispersant state and chemical stability, and finally to enhance the functionality. Different types of oil-in-water emulsions were proved to be effective delivery systems for lipophilic bioactive ingredients, and intensive studies were performed on β-carotene emulsions in the last decade. Emulsions are thermodynamically unstable, and emulsions with intact structures are preferable in delivering β-carotene during processing and storage. β-Carotene in emulsions with smaller particle size has poor stability, and protein-type emulsifiers and additional antioxidants are effective in protecting β-carotene from degradation. Recent development in the design of protein-polyphenol conjugates has provided a novel approach to improve the stability of β-carotene emulsions. When β-carotene is consumed, its bioaccessibility is highly influenced by the digestion of lipids, and β-carotene in smaller oil droplets containing long-chain fatty acids has a higher bioaccessibility. In order to better deliver β-carotene in complex food products, some novel emulsions with tailor-made structures have been developed, e.g., multilayer emulsions, solid lipid particles, Pickering emulsions. This review summarizes the updated understanding of emulsion-based delivery systems for β-carotene, and how emulsions can be better designed to fulfill the benefits of β-carotene in functional foods.

Influence of aqueous phase emulsifiers on lipid oxidation in water-in-walnut oil emulsions

Effects of selected aqueous phase emulsifiers on lipid oxidative stability of water-in-walnut oil (W/O) emulsions stabilized by polyglycerol polyricinoleate (PGPR) were evaluated. The formation of primary oxidation products (lipid hydroperoxides) and secondary oxidation products (headspace hexanal) increased with increasing dodecyltrimethylammonium bromide (DTAB) concentration (0.1-0.2 wt % of emulsions). In contrast, the addition of sodium dodecyl sulfate (SDS) in the aqueous phase reduced lipid hydroperoxide and hexanal formation. In addition, the presence of Tween 20 in the aqueous phase did not significantly influence lipid oxidation rates in W/O emulsions compared to the control (without Tween 20). Whey protein isolate (WPI) was observed to inhibit lipid oxidation in the W/O emulsions (0.05-0.2 wt % of emulsions). Aqueous phase pH had an important impact on the antioxidant capability of WPI, with higher pH improving its ability to inhibit lipid oxidation. The combination of WPI and DTAB in the aqueous phase suppressed the prooxidant effect of DTAB. The combination of WPI and SDS resulted in improved antioxidant activity, with inhibition being greater at pH 7.0 than at pH 3.0. These results suggest that the oxidative stability of W/O emulsions could be improved by the use of suitable emulsifiers in the aqueous phase.