Comparative study of whey protein isolate and gelatin treated by pH-shifting combined with ultrasonication in loading resveratrol

Co-encapsulation of vitamin E and quercetin by soybean lipophilic proteins based on pH-shifting and ultrasonication: Focus on interaction mechanisms, structural and physicochemical properties

This study explored the mechanism of interaction of pH-shifting combined ultrasonication and its effect on soybean lipophilic proteins (SLP) and the potential of modified SLP as the carrier for vitamin E (VE) and quercetin (QU). The spectroscopy results revealed that both VE and QU changed the SLP conformation and exposed hydrophobic groups. The loading rates of VE and QU by SLP with alkaline pH-shifting combined with ultrasonication (300 w,20 min) were 86.91% and 75.99%, respectively. According to the antioxidant analysis, with an increase in the ultrasonication power, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging capacity of the samples increased, where the DPPH and ABTS radical scavenging capacity of sample SQV-6 were 70.90% and 63.43%, respectively. The physicochemical properties, microstructure, and stability of the SLP-VE-QU complex improved significantly. Overall, the present findings broadened the application of simple structural carriers for co-encapsulating functional factors.

Modification of soybean lipophilic protein based on pH-shifting and high-pressure homogenization: Focus on structure, physicochemical properties and delivery vehicle

High-pressure homogenization and pH-shifting can be used to modify soybean lipophilic protein (SLP), and to enhance its ability to deliver vitamin B12. The structural changes of SLP were analyzed by multispectral techniques and the results showed that secondary and tertiary structures of SLP were altered by modification. The modification unfolded the SLP structure, released more free hydrogen ions, and increased positive charge density on the protein surface. Also, the solubility of modified SLP increased by maximum of 34.75 %. Furthermore, molecular docking showed that complexes were formed between SLP and vitamin B12 mainly through hydrogen bonding and hydrophobic interactions, and the encapsulation rate of modified SLP was maximally increased by 2.3 %. In vitro digestion showed that modified SLP enhanced stability and bioaccessibility of vitamin B12. This study provides theoretical basis for modification of SLP and effective delivery of bioactive substances.

Construction of fatty acid-ovalbumin binary complexes to improve the water dispersibility, thermal/digestive stability and bioaccessibility of lutein: A comparative study of different fatty acids

Lipids are increasingly being incorporated into delivery systems due to their ability to facilitate intestinal absorption of lipid-soluble nutrients through molecular solubilization and micellization. In this work, self-assembled complexes of ovalbumin (OVA) and nine dietary fatty acids (FAs) were constructed to improve the processability and absorbability of lutein (LUT). Results showed that all FAs could form stable hydrophilic particles with OVA under the optimized ultrasound-coupled pH conditions. Fourier infrared spectroscopy and transmission electron microscopy analysis showed that these binary complexes effectively encapsulated LUT with an encapsulation rate > 90.0 %. Stability experiments showed that these complexes protected LUT well, which could improve thermal stability and in vitro digestive stability by 1.66-3.58-fold and 1.27-2.74-fold, respectively. Besides, the bioaccessibility of LUT was also enhanced by 7.16-24.99-fold. The chain length and saturation of FAs affected the stability and absorption of LUT. Therefore, these results provided some reference for the selection of FAs for efficient delivery of lipid-soluble nutrients.

Docosahexaenoic acid-mediated milk protein treated by ultrasound-assisted pH shifting for enhanced astaxanthin delivery and processed cheese application

Whey protein isolate (WPI)-based nanodelivery systems have recently attracted an increasing amount of attention. Despite this, research focusing on milk protein concentrate (MPC) and micellar casein (MCC) as carriers loaded in hydrophobic compounds is lacking. This study investigated the mediated effect of docosahexaenoic acid (DHA) in 3 different milk proteins for the embedding of astaxanthin (ASTA) after ultrasound-assisted pH-shifting treatment. We then evaluated the application of milk protein carriers in cheese processing by comparing MPC, MCC, and WPI. The particle size, polydispersity index, and zeta potential results of the milk protein-DHA complex suggested that the addition of 0.36 μmol/mL DHA optimized the delivery of milk protein to ASTA. All 3 DHA-mediated milk proteins induced an improvement in encapsulation efficiency and antioxidant properties of ASTA. Furthermore, the DHA-mediated MPC and MCC played a stronger role in improving the bioaccessibility and thermal and storage stability of ASTA than those without DHA. Tests conducted to examine the application in cheese production indicated that MCC carrier had a positive effect on the texture of cheeses. However, the delivery effect was dependent on the milk protein variety, and MCC exhibited the best protection ability of ASTA, followed by MPC and WPI. The simulated digestion and storage stability results of cheese further confirmed that the protein encapsulation mediated by DHA was more conducive to ASTA absorption. These findings suggested that the DHA-mediated milk protein complexes studied here may be suitable hydrophilic delivery carriers for the hydrophobic nutrient ASTA, potentially playing different roles in improving its storage stability and bioaccessibility.

Research progress of protein complex systems and their application in food: A review

Among the common natural biomolecules, the excellent properties of proteins have attracted extensive attention from researchers for functional applications, however, in native form proteins have many limitations in the performance of their functional attribute. However, with the deepening of research, it has been found that the combination of natural active substances such as polyphenols, polysaccharides, etc. with protein molecules will make the composite system have stronger functional properties, while the utilization of pH-driven method, ultrasonic treatment, heat treatment, etc. not only provides a guarantee for the overall protein-based composite system, but also gives more possibilities to the protein-composite system. Protein composite systems are emerging in the fields of novel active packaging, functional factor delivery systems and gel systems with high medical value. The products of these protein composite systems usually have high functional properties, mainly due to the interaction of the remaining natural active substances with protein molecules, which can be broadly categorized into covalent interactions and non-covalent interactions, and which, despite the differences in these interactions, together constitute the cornerstone for the stability of protein composite systems and for in-depth research.

WPI-coated liposomes as a delivery vehicle for enhancing the thermal stability and antioxidant activity of luteolin

The practical application of luteolin in food systems faces challenges due to its inherent instability. This study aimed to develop luteolin-loaded liposomes coated with whey protein isolate (WPI) to enhance the thermal stability and antioxidant activity of luteolin. The physical characteristics of both luteolin-loaded liposomes (LUT-Lips) and WPI-coated luteolin-loaded liposomes (WPI-LUT-Lips) were assessed. At a 5% WPI concentration, WPI-LUT-Lips demonstrated excellent dispersibility and improved encapsulation efficiency. WPI interacted with the liposome membrane via hydrophobic forces, hydrogen bonding, and electrostatic contact force, resulting in an efficient coating. Differential scanning calorimetry confirmed that WPI-LUT-Lips exhibited greater thermal stability compared to LUT-Lips, attributed to the protective effect of the WPI. Furthermore, WPI-LUT-Lips displayed superior antioxidant activity, as evidenced by their DPPH scavenging activity (86.36 ± 1.95%), TBARS reduction (25.33 ± 1.90%), and reducing power (82.86 ± 1.42%). Therefore, WPI-coated luteolin-loaded liposomes offer a promising way to enhance luteolin's integration into food systems.

Comparison of milk protein concentrate, micellar casein, and whey protein isolate in loading astaxanthin after the treatment of ultrasound-assisted pH shifting

Milk proteins can be used as encapsulation walls to increase the bioavailability of active compounds because they can bind hydrophobic, hydrophilic, and charged compounds. The objective of this study was to investigate the effects of astaxanthin (ASTA) encapsulation and the functional properties of milk protein and ASTA nanocomposites by an ultrasound-assisted pH-shifting treatment of different milk proteins, including milk protein concentrate (MPC), micellar casein (MCC), and whey protein isolate (WPI). The ultrasound-assisted pH-shifting treatment of milk protein helped to improve the encapsulation rate of ASTA. Therein, MCC showed great improvement of encapsulating ASTA after co-treatment with the raised encapsulated rate of 5.11%, followed by WPI and MPC. Furthermore, the nanocomposites of ASTA with milk protein exhibit improved bioavailability, antioxidant capacity, and storage stability. By comparison, MCC-encapsulated ASTA has the best storage stability, followed by MPC, and WPI-encapsulated ASTA has the least stability over a 28-d storage period. The results of intrinsic fluorescence and surface hydrophobicity showed that milk protein underwent fluorescence quenching after binding to ASTA, which was due to the hydrophobic sites of the protein being occupied by ASTA. In general, the nanocomposites of milk protein and ASTA fabricated by using an ultrasound-assisted pH-shifting treatment have the potential to be better nano-delivery systems for ASTA in functional foods, especially MCC, which showed excellent performance in encapsulation after treatment technique.

Mechanism of ultrasonic combined with different fields on protein complex system and its effect on its functional characteristics and application: A review

In recent years, new food processing technologies (such as ultrasound, high-pressure homogenization, and pulsed electric fields) have gradually appeared in the public 's field of vision. These technologies have made outstanding contributions to changing the structure and function of protein complexes. As a relatively mature physical field, ultrasound has been widely used in food-related fields. However, with the gradual deepening of related research, it is found that the combination of different fields often makes some characteristics of the product better than the product under the action of a single field, which will not only lead to a broader application prospect of the product, but also make the product a better solution in some special fields. There are usually synergistic and antagonistic effects when multiple fields are combined, and these effects will also gradually enlarge the interaction between different components of the protein complex system. In this paper, while explaining the mechanism of ultrasonic combined with other fields affecting the steric hindrance and shielding site of protein complex system, we will further explain the effect of this effect on the function and application of protein complex system.

Enhanced encapsulation of lutein using soy protein isolate nanoparticles prepared by pulsed electric field and pH shifting treatment

In this study, soy protein isolate (SPI) was modified by a pulsed electric field (PEF) combined with pH shifting treatment (10 kV/cm, pH 11) to prepare SPI nanoparticles (PSPI11) for efficient loading of lutein. The results showed that when the mass ratio of SPI to lutein was 25:1, the encapsulation efficiency of lutein in PSPI11 increased from 54% to 77%, and the loading capacity increased by 41% compared to the original SPI. The formed SPI-lutein composite nanoparticles (PSPI11-LUTNPs) had smaller, more homogeneous sizes and larger negative charges than SPI7-LUTNPs. The combined treatment favored the unfolding of the SPI structure and could expose its interior hydrophobic groups to bind with lutein. Nanocomplexation with SPIs significantly improved the solubility and stability of lutein, with PSPI11 showing the greatest improvement. As a result, PEF combined with pH shifting pretreatment is an effective method for developing SPI nanoparticles loaded and protected with lutein.

Development of self-assembled zein-fucoidan complex nanoparticles as a delivery system for resveratrol

Resveratrol is a well-studied dietary polyphenol with diverse health-promoting bioactivities. However, the aqueous insolubility and chemical instability of resveratrol hamper its practical application. This study set out to address these limitations by constructing zein-fucoidan composite nanoparticles as a delivery system of resveratrol. The optimized resveratrol-loaded zein-fucoidan particles (RE-ZFP) were obtained at zein-to-fucoidan ratio of 2:1 (w/w) and zein-to-resveratrol ratio of 10:1 (w/w), and RE-ZFP showed evenly distributed and smoothly spherical microstructures, mean particle size of 121 nm, ζ-potential of - 41 mV, encapsulation efficiency for resveratrol of 95.4%. Electrostatic, steric, hydrophobic, and hydrogen-bonding interactions were major forces required to form RE-ZFP. In addition, RE-ZFP exhibited greater photostability and colloidal stability (including pH, ionic, and storage stabilities) than resveratrol-loaded zein particles (RE-ZP). Particularly, RE-ZFP showed fairly good pH stability. Moreover, zein-fucoidan-based delivery system exhibited a controlled release of resveratrol under in vitro digestion. Finally, zein-fucoidan nanocarriers presented extremely low cytotoxicity to HIEC-6 cells. All the findings demonstrate that the zein-fucoidan nanoparticles developed in the current work will be a prospective strategy for loading resveratrol and other hydrophobic bioactive ingredients and thus extending their application in nutraceuticals or pharmaceuticals.

Soy lipophilic protein self-assembled by pH-shift combined with heat treatment: Structure, hydrophobic resveratrol encapsulation, emulsification, and digestion

This study evaluates the effect of pH (pH 3 and 11) and heat treatment (60 °C) in modifying the soybean lipophilic protein (LP) for the development of an encapsulation system to co-deliver resveratrol (Res) and vitamin D3. The structural and functional properties of LP after the modification will change to varying degrees. Meanwhile, Res was loaded into the hydrophobic core of LP, and the resulting Res-loaded structures have a uniform particle size distribution and a high encapsulation efficiency (78%). When the amount of Res encapsulation increases, the emulsification and oxidation resistance of the Pickering emulsion increased; the interfacial tension and interfacial protein adsorption increased to 11.21 mN/m and 97.34%, respectively. During simulated gastrointestinal digestion, the Pickering emulsion prepared with LP-Res nanoparticles at pH 11, 60 °C (pH 11, 60 °C-LP-Res) effectively protected Res and vitamin D3 from degradation or precipitation, indicating a significant increase in bioavailability.

Effect of ultrasonic power on the emulsion stability of rice bran protein-chlorogenic acid emulsion

In this study, rice bran protein-chlorogenic acid (RBP-CA) emulsion was subjected to an ultrasonic-assisted treatment technique. The encapsulation efficiency and loading capacity of chlorogenic acid (CA), and the morphology, particle size, zeta (ζ)-potential, atomic force microscopy image, viscosity, turbidity, and interfacial protein content of the emulsion under different ultrasonic power were investigated. The results revealed that the emulsion exhibited an encapsulation efficiency and loading capacity of 86.26 ± 0.11% and 17.25 ± 0.06 g/100 g, respectively, at an ultrasonic power of 400 W. In addition, the size of the emulsion droplets decreased and became more evenly distributed. Furthermore, the viscosity of the emulsion decreased significantly, and it exhibited a turbidity and interfacial protein content of 24,758 and9.34 mg/m², respectively. Next, the storage, oxidation, thermal, and salt ion stabilities of the emulsion were evaluated. The results revealed that the ultrasonic-assisted treatment considerably improved the stability of the emulsion.

Sodium Dodecyl Sulfate-Dependent Disassembly and Reassembly of Soybean Lipophilic Protein Nanoparticles: An Environmentally Friendly Nanocarrier for Resveratrol

The development of protein-based nanocarriers to improve the water solubility, stability, and bioavailability of hydrophobic or poorly soluble bioactive molecules has attracted increasing interest in the food and pharmaceutical industries. In this study, a network-like nanostructure of soybean lipophilic protein (LP) was obtained through sodium dodecyl sulfate (SDS)-dependent decomposition and recombination. This nanostructure served as an excellent nanocarrier for resveratrol (Res), a poorly soluble biologically active molecule. The structure of LP gradually decomposed into its independent subunits at SDS concentrations ≤5% (w/v). After the removal of SDS, the dissociated subunits partially reassembled into a fibrous network-like nanostructure in which the Res molecules were encapsulated, and they preferentially interacted with the hydrophobic subunits (α and α' subunits and the 24 kDa subunit) of the protein. This system exhibited a high encapsulation efficiency (95.93%), high water solubility (85.29%), extraordinary oxidation resistance (DPPH radical scavenging activity of 67.1%), and improved Res digestibility (78.7%).

Construction of biopolymer-based nanoencapsulation of functional food ingredients using the pH-driven method: a review

Biopolymer-based nanoencapsulation presents great performance in the delivery of functional food ingredients. In recent years, the pH-driven method has received considerable attention due to its unique characteristics of low energy and organic solvent-free during the construction of biopolymer-based nanoencapsulation. This review summarized the fundamental knowledge of pH-driven biopolymer-based nanoencapsulation. The principle of the pH-driven method is the protonation reaction of functional food ingredients that change with pH. The stability of functional food ingredients in an alkaline environment is a prerequisite for the adoption of this method. pH regulator is also an important influencing factor. Different coating materials used to the pH-driven nanoencapsulation were discussed, including single and composite materials, mainly focusing on proteins. Besides, the application evaluations of pH-driven nanoencapsulation in food were analyzed. The future development trends will be the influence of pH regulators on the carrier, the design of new non-protein-based carriers, the quantification of driving forces, the absorption mechanism of encapsulated nutrients, and the molecular interaction between the wall material and the intestinal mucosa. In conclusion, pH-driven biopolymer-based nanoencapsulation of functional food ingredients will have broad prospects for development.

Encapsulation of phenolic compounds within food-grade carriers and delivery systems by pH-driven method: a systematic review

In comparison to conventional encapsulation methods of phenolic compounds (PCs), pH-driven method is green, simple and requires low energy consumption. It has a huge potential for industrial applications, and can overcome more effectively the aqueous solubility, stability and bioavailability issues related to PCs by changing pH to induce the encapsulation of PCs. This review aims to shed light on the use of pH-driven method for encapsulating PCs. The preparation steps and principles governing pH-driven method using various carriers and delivery systems are provided. A comparison of pH-driven with other methods is also presented. To circumvent the drawbacks of pH-driven method, improvement strategies are proposed. The essence of pH-driven method relies simultaneously on alkalization and acidification to bind PCs and carriers. It is used for the development of nanoemulsions, liposomes, edible films, nanoparticles, nanogels and functional foods. As a result of pH-driven method, PCs-loaded carriers may have smaller size, high encapsulation efficiency, more sustained-release and good bioavailability, due mainly to effects of pH change on the structure and properties of PCs as well as carriers. Finally, modification of wall materials and type of acidifier are considered as efficient approaches to improve the pH-driven method.