Whey Protein Isolate Research Articles

The effect of whey/soy protein fibril systems on the properties of fish gelatin stabilized emulsion gels

In this study, we investigated the effects of whey protein isolate fibril systems (WPF) and soy protein isolate fibril systems (SPF) combined with fish gelatin (FG) on the formation of emulsion gels. The aim was to evaluate how the origin and concentration of these fibril systems influence the structural, interfacial, and rheological properties of FG-stabilized emulsion gels, as well as their impact on creaming stability. FG was mixed with varying concentrations (0–2%) of WPF and SPF at pH 7, forming electrostatic complexes due to the opposite charge interactions between FG and the protein fibril dispersions. The results revealed that adding WPF and SPF increased surface hydrophobicity and enhanced interfacial activity. Increasing WPF concentrations led to a gradual decrease in emulsion droplet size owing to the increased absorbed protein content at the interface. Additionally, there was a significant improvement in the storage modulus of the emulsion gels. Conversely, introducing a small amount (0.1%) of SPF to FG increased the particle size, suggesting potential coalescence, but further increases in SPF concentration considerably reduced the particle size. Furthermore, SPF enhanced the viscoelasticity at lower concentrations, possibly due to a more uniform distribution within the continuous phase. However, excess SPF reduced the storage modulus of the emulsion gels. Our study provides valuable theoretical insights for the application of protein fibril systems in emulsion gel systems.

Heat-induced interactions between microfluidized hemp protein particles and caseins or whey proteins

The rising demand for sustainable proteins leads to increased interest in plant proteins like hemp protein (HP). However, commercial HP's poor functionality, including heat aggregation, limit its use. This study explored the heat-induced interactions of hemp protein particles (HPPs) with milk proteins, specifically whey proteins and caseins. Using various analysis techniques—static light scattering, TEM, SDS electrophoresis, surface hydrophobicity, and free sulfhydryl content—results showed that co-heating HPPs with whey protein isolate (WPI) or sodium caseinate (NaCN) at 95 °C for 20 min reduced HPPs aggregation. HPPs/WPI particles had a d4,3 of ∼3.8 μm, while HPPs/NaCN were ∼1.9 μm, compared to ∼27.5 μm for HPPs alone. SDS-PAGE indicated that whey proteins irreversibly bound to HPPs, through disulfide bonds, whereas casein bound reversibly, possibly involving the chaperone-like property of casein. This study proposes possible mechanisms by which HPPs interact with milk proteins and impact protein aggregation. This may provide opportunities for developing hybrid protein microparticles.

Engineering effects of hydrocolloids on drying kinetics, powder characteristics, and antioxidant preservation in grape powder

This study explores the preservation of bioactive compounds in grape powder via encapsulation using spray drying, focusing on the impact of hydrocolloids—whey protein isolate (WPI), gum arabic, and high methoxy pectin—on critical engineering parameters. The research analyzes the effects of these encapsulants on rheological properties, drying kinetics, droplet formation, and drying curves, all of which influence the powder's morphology and antioxidant retention. Drying times ranged from 1.05 to 1.14 s, with distinct drying curves reflecting the relationship between moisture content and time, correlating with key powder properties such as bulk and tap density, flowability, and compressibility. Dimensionless numbers, including Peclet and Reynolds numbers, showed significant correlations with both powder characteristics and bioactive retention, highlighting the role of efficient heat and mass transfer in preserving phenolic content. The study concludes that optimal formulations, particularly those combining WPI and pectin, result in uniform droplet sizes, faster drying rates, and enhanced bioactive stability, providing insights for optimizing spray drying processes to produce high-quality, stable food powders.

Mechanisms of Pickering emulsion formation and stabilization by composite arabinoxylan–whey protein isolate particles

Few systematic studies were performed into the properties of arabinoxylan (AX) and protein composite particles, and their mechanisms of action in an emulsion remain largely unknown. In this study, composite particles based on different concentrations of AX and whey protein isolate (WPI) were constructed, and a systematic characterization was conducted to determine their functional properties. A good compatibility was found between WPI and AX, and the composites exhibited an enhanced thermal stability and consistent particle sizes. Molecular interactions, including hydrogen bonds, were detected between WPI and AX, and the composite particles containing 4% AX exhibited the lowest interfacial tension and the strongest emulsification ability. AX promoted protein adsorption on the oil phase surface, and the desorption energy of the composite particles at the oil/water interface increased accordingly. The stability of an emulsion stabilized by AX–WPI was confirmed by rheological and microstructural investigations. This study therefore provides theoretical support for the application of such emulsions.

A protectant for Lactobacillus rhamnosus based on whey protein isolate and isomalt: Stress resistance and underlying mechanisms

Probiotics are exposed to a variety of abiotic and biotic stresses during food fermentation and production, such as acidity, heat, osmolality, and oxidation, which affect their metabolic activity and efficiency. Therefore, it is essential to develop new protective agents to maintain the activity and stability of probiotics. This study introduces a new protectant, spray-dried whey protein isolate (WPI) and isomaltose (ISO). We evaluated the effects of four WPI-ISO ratios (1:0, 2:1, 1:1, 1:2) on the physical properties, including moisture content, water activity (aw), wettability, and glass transition temperature. In addition, we evaluated the environmental tolerance of Lactobacillus rhamnosus to different WPI-ISO ratios under thermal, storage, and simulated gastrointestinal conditions. The results showed that the moisture content (< 7 %) and water activity (< 0.3) of the protectant and probiotic powders met storage stability requirements. The moisture content, water activity, wettability index (WI), and glass transition temperature decreased significantly with the addition of isomalt, thereby improving the pressure resistance of L. rhamnosus through the synergistic effect of WPI and ISO. The WPI-ISO protectant not only improved the environmental tolerance and wettability of probiotics by reducing the moisture content and water activity but also significantly improved the survival rate of L. rhamnosus under various stress conditions such as high temperature and gastrointestinal environment. L. rhamnosus maintains good activity with a viable bacterial count of over 9 lg CFU/g after 90 days of storage, demonstrating effective protection against the environment stress. This study provides a promising new strategy to improve the stability of probiotics in the food industry.

Nanoencapsulation of quinoa oil enhanced the antioxidant potential and inhibited digestive enzymes

Quinoa oil is rich in unsaturated fatty acids and vitamin E, but its instability limits its application in food, pharmaceutical, and cosmetic products. Nanoencapsulation emerges as a promising strategy to promote water dispersibility, preserve and enhance functional properties, and increase the bioavailability of bioactive compounds. This study encapsulated quinoa oil through O/W emulsification, using porcine gelatin (OG) and isolated whey protein (OWG) as encapsulating agents. The particles were characterized by different physical and chemical methods and evaluated in vitro for cytotoxicity using Chinese hamster ovary (CHO) cells, human hepatocarcinoma cells (HepG2) and epithelial cells, and bioactive potential through the determination of Total Antioxidant Capacity (CAT) (acidic and neutral media) and iron chelation, and inhibition of digestive enzymes (α-amylase and amyloglucosidase). OG and OWG particles presented smooth surfaces, with an average size between 161 ± 7 and 264 ± 6 nm, with a polydispersity index of 0.11 ± 0.03 and 0.130 ± 0.04, encapsulation efficiency of 74 ± 1.47 % and 83 ± 2.92 %, and water dispersibility >70 %, respectively. Free and nanoencapsulated quinoa oil did not show cytotoxic effects (cell viability >70 %). Nanoencapsulation promoted the enhancement of the antioxidant activity of quinoa oil in the range of 50–63 % in a neutral medium and 96–153 % in an acidic medium than free oil (p < 0.05). OG and OWG also enhanced the inhibition of the enzymes α-amylase (by 5–7 %) and amyloglucosidase (6–9 times more) than free oil (p < 0.05). The results showed that nanoencapsulation increased the potential for quinoa oil application, enabling the development of innovative products.

Comparative study of interaction and complex formation of Tremella fuciformis polysaccharide with whey protein, lentil protein, and soy protein isolates

The electrostatic interactions and complex formation of Tremella fuciformis polysaccharide (TPS) with whey protein (WPI), lentil protein (LPI), and soy protein (SPI) isolates were studied. The molecular size and components in each protein isolate complexed with TPS were characterized, along with the structural changes in the protein components, induced by TPS complexation. The stability of emulsions prepared with protein:TPS complexes was also evaluated (pH 4.5). Compared to WPI, the LPI and SPI protein components exhibited more negative charges and larger molecular sizes. Independent of the isolate type, pHc of all protein:TPS systems remained unchanged and pHɸ1 shifted to higher pHs as the protein/TPS ratio increased; the pHopt of WPI:TPS and SPI:TPS occurred at higher values as the protein/TPS ratio increased, while the pHopt of LPI:TPS system was less dependent on the biopolymer mixing ratio, probably due to the lower solubility of LPI. Protein components such as β-LG in WPI, convicilin, vicilin, and basic legumin in LPI, and α’ subunits of 7S β-conglycinin and acidic subunits of 11S glycinin in SPI might be the main components interacting with TPS for complex formation. Different proteins exhibited distinct trends in changing their secondary structural elements when interacting with TPS. At pH 4.5, a high proportion of TPS increased the stability of protein emulsion, regardless of the protein used. The WPI:TPS emulsions with low content of TPS were highly destabilized due to the formation of insoluble WPI:TPS complex coacervates, a phenomenon not observed in emulsions stabilized by the LPI:TPS or SPI:TPS systems.

Storage stability and antioxidant activity of astaxanthin and beta-carotene as affected by the architecture of O/W emulsions of milk proteins

Astaxanthin and β-carotene are among the potential anti-oxidant carotenoids with strong health promoting features. However, their sensitivity to light, heat and mechanical forces limit their application in food processing and storage conditions. The design of food matrix system, such as emulsions, that could prevent them from exposure to environmental factors will be utmost importance to slow down their degradation. In this study, O/W emulsion systems containing sunflower oil were prepared by applying ultrasound treatment and using different stabilizers (i.e. whey protein isolate (WPI) and sodium caseinate; NaCAS), co-surfactants (pectin and lecithin) while their performance against physical and chemical stability were investigated. The WPI– lecithin system produced emulsion droplets with Average diameter in the range of 560–2900 nm with a zeta-potential in the range of (−31) – (−34) mV, whereas the NaCAS – lecithin systems produced emulsion droplets with average diameter in the range of 230–240 nm and zeta potential of (−44) – (−48) mV. These values have a direct effect on the physical stability and chemical stability of the carotenoids in the emulsions. Astaxanthin was found to be more sensitive than β-carotene to ultrasound processing conditions. The designed emulsion systems slowed down the degradation of the carotenoids and maintained their DPPH scavenging properties during storage with astaxanthin loaded emulsions exhibiting better DPPH activity than β-carotene loaded emulsions.

Characteristics of pomegranate (Punica granatum L.) peel polyphenols encapsulated with whey protein isolate and β-cyclodextrin by spray-drying

Pomegranate peel polyphenols (PPPs) are recognized as promising food additives due to their diverse bioactivities; however, their application is limited by poor stability. To address this critical issue, three types of PPPs microcapsules were prepared using β-cyclodextrin (CD), whey protein isolate (WPI), and a composite material of CD-WPI through ultrasound treatment (US). Results revealed that ultrasound treatment can enhance the PPPs-wall material interaction, as evidenced by MD simulations. The encapsulation efficiency of CD-WPI-PPPs was 93.73 %, which was significantly higher than that of CD-PPPs and WPI-PPPs (p < 0.05). The degradation rate constant of CD-WPI-PPPs was reduced by 95.83 %, and its t1/2 was extended by 23-fold compared to that of unencapsulated PPPs. Furthermore, CD-WPI-PPPs exhibited greater DPPH scavenging activity and inhibited polyphenol release during oral and gastric digestion while promoting release during intestinal digestion. These outcomes were attributed to enhanced integrity and interactions between PPPs and composite materials in the microcapsules formed through ultrasound treatment, as supported by SEM images and FT-IR spectra. Consequently, the application of US in the preparation of PPPs microcapsules presents a promising strategy for developing natural nutrient additives for food applications, thereby enhancing the functional properties of food products.

Impact of microstructure of whey protein gels on in vitro gastric protein digestion is sustained after oral structural breakdown by mastication

Gastric protein digestion can be influenced by food micro- and macrostructure. Understanding the interplay between microstructure and macrostructural breakdown during oral processing is crucial to enhance the nutritional value of protein-rich foods. This study compared the in vitro gastric protein digestion of whey protein gels differing in microstructure before and after mastication. Whey protein isolate was mixed with κ-carrageenan to obtain heat-induced gels differing in microstructure (homogeneous, coarse stranded, protein continuous, bi-continuous). Gel boli were collected from 14 participants. The number, size and total surface area of bolus fragments were determined. In vitro gastric protein digestion was quantified following the INFOGEST 2.0 protocol with minor modifications. Before mastication, coarse stranded gels showed the highest digestion rate (1.07 mmol L−1∙g dry matter−1/h), while homogeneous, protein continuous and bi-continuous gels showed lower and similar digestion rates (0.82–0.87 mmol L−1∙g dry matter−1/h). After mastication, the total surface area of coarse stranded gels increased 7.9-fold leading to a 1.9-fold increase in digestion rate. In contrast, a 3.4-fold increase in total surface area of bi-continuous gels caused a 2.8-fold increase in digestion rate. The total surface area of homogeneous and protein continuous gels increased 3.1- to 3.6-fold upon mastication resulting in a 1.7- to 1.9-fold increase in digestion rate. The increase in protein hydrolysis did not correlate with the degree of structural breakdown after mastication across gels differing in microstructure. We conclude that the impact of microstructure of whey protein gels on in vitro gastric protein digestion is sustained after oral structural breakdown by mastication.

Amphiphilic colloidal particles/Ca2+ reinforced edible agar nanocomposite film by multiple cross-linking/microphase separation strategies

The agar (AG) film exhibited poor mechanical and water-resistant properties which limited its application for food packaging. The structural modification of AG nanocomposite film greatly impacts their macroscopic properties. In this paper, edible AG nanocomposite films were achieved by incorporating colloidal particles based on conjugates of whey protein isolate (WPI) and alginate oligosaccharides (AOS) as the nanofiller to obtain the micro-phase separation structure and the multiple cross-linking network with the synergistic interactions of the Ca2+ crosslinking. Firstly, WPI-AOS colloidal particles were synthesized through the Wet-heating Maillard reaction. Good compatibility between WPI-AOS colloidal particles and AG was exhibited, resulting in improved mechanical and water-resistant properties of AG composite films. Compared to pure AG film, the tensile strength (TS) of the agar composite film with 10% WPI-AOS colloidal particles increased significantly to 81.87 MPa from 24.02 MPa, and the elongation at break (EAB) also improved to 46.25% from 18.65%. The moisture content (MC), water solubility (WS), and water vapor permeability (WVP) of the AG composite film decreased by 33.1%, 18.0%, and 22.4% respectively. In addition, the multiple cross-linking network hindered the relative sliding between the AG molecular chain, which resulted in improved thermal stability of the composite film. Using soft colloidal particles as nanofillers to fabricate edible films for improving their properties is an effective and promising strategy.

Exploration of binding mechanism of whey protein isolate and proanthocyanidin: Spectroscopic analysis and molecular dynamics simulation

The non-covalent whey protein isolate-proanthocyanidin (WPI-PC) complex was constructed and possessed superior anti-muscle attenuation activity in our previous study. While the non-covalent binding mechanism of WPI and PC remains unclear. The interaction mechanism of whey protein isolate (WPI) and proanthocyanidin (PC) was explored using multispectral analysis and molecular dynamics (MD) simulation. The results indicated that the non-covalent binding of PC and WPI led to fluorescence quenching, causing the conformational changes and microenvironment changes of WPI. The surface hydrophobicity of WPI-PC complex was reduced by 42.36 % compared with WPI (P < 0.05). The hydrogen bond and hydrophobic interaction were involved in the interaction between WPI and PC, and hydrogen bond played a dominant role. The WPI-PC complex was irregular and showed a smaller sheet structure. The PC and WPI remained a stable binding mainly through 15 key residues, especially the energy contribution of LEU 39. Additionally, the flexibility and fluctuation of individual amino acid residues in WPI were altered after binding to PC. It is hoped that this study could provide theoretical basis for the application of WPI and PC in functional foods.

Pickering Foam Stabilized by Diacylglycerol-Based Solid Lipid Nanoparticles: Effect of Protein Modification.

Pickering foams have great potential for applications in aerated foods, but their foaming ability and physical stability are still far from satisfactory. Herein, solid lipid particles (SLNs) were fabricated by using diacylglycerol of varying acyl chain lengths with modification by a protein. The SLNs showed different crystal polymorphisms and air-water interfacial activity. C14-DAG SLN with a contact angle ∼ 79° formed aqueous foam with supreme stability and high plasticity. Whey protein isolate and sodium caseinate (0.1 wt %) considerably enhanced the foamability and interfacial activity of SLNs and promoted the packing of particles at the bubble surface. However, high protein concentration caused foam destruction due to the competitive adsorption effect. β-sheet increased in protein after adsorption and changed the polymorphism and thermodynamic properties of SLN. The foam collapsing behaviors varied in the presence of protein. The results gave insights into fabricating ultrastable aqueous foams by using high-melting DAG particles. The obtained foams demonstrated good temperature sensitivity and plasticity, which showed promising application prospects in the food and cosmetic fields.

Emulsion Stability and Rheological Properties of Emulsions Prepared with Ozonized Hazelnut Oil

In this study, physical and rheological characteristics of the emulsion stabilized with whey protein isolate (WPI) at a concentration of 0.25% (w/w) and containing ozone applicated hazelnut oil (OHO) were studied. The hazelnut oil was subjected to ozone gas exposure for durations of 1, 5, 30, 60, 180, and 360 min. The emulsions made with both control (HO) and OHO were analysed to assess emulsion properties. It was observed that as the duration of ozone application increased, the emulsion activity index (EAI) experienced a decrease. Specifically, ozone applications of 30, 60, and 180 min significantly reduced emulsion stability index (ESI). The creaming ratio of emulsions formulated with OHO for durations of 1, 5, 30, 60, and 180 min were found to be 23%, 20%, 18%, 16%, and 44%, respectively. Optical microscopy revealed that significant flocculated droplet formed in emulsions including OHO. The longer time the ozone application resulted that the emulsions exhibited more solid-like behaviour. Furthermore, differential scanning calorimeter (DSC) was utilized to assess the changes in the melting and cooling profiles of hazelnut oil after being applicated with ozone. An increase in ozone application duration led to the melting peaks broadening and shifting towards lower temperatures. Also, ozone application caused that the sharp exothermic crystallization shifted towards lower temperatures and become broader and less pronounced as the duration of the application increased.

Whey protein isolate-tamarind seed gum complexes stabilized dysphagia friendly high internal phase emulsions: The effects of pH conditions and mass ratios

Dysphagia is a common malfunction affecting a large population worldwide, yet the range of food available to the patients is limited. The objective of this study was to utilize a complex of whey protein isolate (WPI) and tamarind seed gum (TG) as novel emulsifiers to stabilize HIPEs, and further explore WPI-TG-based HIPEs' potential as dysphagia-friendly foods for special medical purposes (FSMP). The results indicated that WPI-TG forms complexes through hydrogen bonding and electrostatic interactions (pH 3 and 4). Additionally, TG induced changes in the secondary and tertiary structures of WPI. The particle size of HIPEs prepared from WPI-TG complexes was found to be reduced. Meanwhile, with the decrease in pH from 7 to 3, the variation in complexes ζ-potential led to an initial increase followed by a subsequent drop in the particle size of HIPEs. The rheological results indicated that WPI-TG-based HIPEs exhibit low-risk swallow characteristics, including shear thinning, high storage modulus, and good recovery ability. Further analysis using the IDDSI testing demonstrated that WPI-TG-based HIPEs under pH 3 and 4 can potentially be dysphagia-friendly FSMPs. After undergoing thermal treatment or long-term storage, WPI-TG-based HIPEs at pH 3 and 4 consistently maintained compliance with the IDDSI testing. These findings provided valuable insights for the future utilization of HIPEs in developing dysphagia-friendly FSMPs.

Fabrication and characterization of whey protein isolate-tryptophan nanoparticles by pH-shifting combined with heat treatment

L-Tryptophan (Trp) is an essential amino acid with numerous health benefits. However, incorporating Trp into food products is limited due to its pronounced bitter taste. Encapsulating Trp in nanoparticles by using other natural biopolymers is a potential strategy to mask the bitter taste of Trp in the final products. Whey protein isolate (WPI), composed of alpha-lactalbumin (α-LA), bovine serum albumin (BSA), and beta-lactoglobulin (β-LG), has played a crucial role in delivering bioactive compounds. In order to incorporate Trp within WPI, the present study used a combination of pH-shifting andthermal treatment to fabricatewhey protein isolate-tryptophan nanoparticles (WPI-Trp-NPs). During the pH-shifting technique, WPI unfolds at high pH, such as pH 11, and the dissociated WPI molecules are refolded when pH is shifted back to neutral, creating particles with uniform dispersion and encapsulating smaller particles surrounding them in solution. Further, the well-distributed nanoparticles formed by pH-shifting might encourage the formation of more uniform nanoparticles during subsequent thermal treatment. TheWPI-Trp particles have an average particle size of 110.1 nm and a low average PDI of 0.20. Fluorescence spectroscopy confirmed the encapsulation of Trp by WPI, which shows higher fluorescence when the Trp is encapsulated by the WPI. Surface hydrophobicity, circular dichroism, particle size, free sulfhydryl, and antioxidant activity were used to characterize the WPI-Trp-NPs. WPI-Trp-NPs formed by pH-shifting combined with heating showed a higher surface hydrophobicity and free sulfhydryl content than the untreated WPI-Trp mixture. The conversion of α-helix into random coil in the WPI secondary structure indicated a more disordered structure of the modified whey protein. Molecular docking results indicate the interactions between Trp and WPI, including alpha-lactalbumin (α-LA), bovine serum albumin, and beta-lactoglobulin (β-LG), were mainly driven by hydrophobic interactions and hydrogen bonding. The binding affinity between Trp and these proteins was ranked as α-LA>BSA>β-LG. The combination of pH-shifting and heating improved the functionalityof WPI and was an effective way to fabricate WPI-Trp nanoparticles.

Dynamic high-pressure microfluidization assisted with galactooligosaccharide-modified whey protein isolate: Investigating its effect on relieving intestinal barrier damage

The study aimed to investigating the mechanisms of relieved intestinal barrier damage by dynamic high-pressure microfluidization assisted with galactooligosaccharide- glycated whey protein isolate. The modifications changed the multi-structure, and the modified whey protein isolate could promote the proliferation of IEC-6 cells and contributed to the restoration of LPS-induced occludin damage in IEC-6 cells. Also, it could repair cyclophosphamide-induced ileal villus rupture and crypt destruction in BALB/c mice, significantly altered the abundance of dominant bacteria, which were associated with propionic acid, butyric acid, isovaleric acid, and valeric acid. Ileum transcriptomics revealed that the modified whey protein isolate significantly regulate of the levels of Cstad, Cyp11a1, and Hs6st2 genes, relating to the increase of propionic acid, isovaleric acid, and valeric acid. In conclusion, galactooligosaccharide- modified whey protein isolate could regulate the level of Cstad, Cyp11a1 and Hs6st2 genes by altering the gut microbial structure and the level of SCFAs, thereby repairing the intestinal barrier.

Targeted treatment of kidney using intravenous and intraarterial delivery of whey protein isolate-based microgels

Here we report a promising whey protein isolate (WPI)-stabilized emulsion microgels for targeted drug delivery into the kidney. Investigation of stability revealed time-dependent degradation of the microgels starting at 72 h. Cytotoxicity studies showing increased sensitivity in Hek239 and Jurkat cells. A biodegradation assay underscored the role of macrophages in the destruction process of microgel particles. The efficiency of targeting the microgels for the kidney was assessed by biodistribution using intravenous and intraarterial delivery. Tail vein administration demonstrated long-term (minimum 5 days) selective accumulation not only in the liver but also in the kidneys. Renal artery injection of microgels resulted in an expected local increase in fluorescence in the target kidney in the first minutes after injection. In contrast, at 1 and 3 h there was an atypical accumulation of the Cy7 fluorescent signal in the opposite kidney. However, at 1 and 5 d the fluorescent signal predominated in the target kidney again and was higher in comparison with intravenous administration. Histological analysis validated the safety of WPI-based microgels using different methods of administration. By fine-tuning the physicochemical properties and delivery methods, the developed microgels offer an adjusted therapeutic approach with reduced side effects. They present new prospects for the treatment of kidney disorders using both intravenous administration and minimally invasive endovascular approach.

Mechanistic insights into the interaction of Lycium barbarum polysaccharide with whey protein isolate: Functional and structural characterization

Protein-polysaccharide interactions are crucial for food system structure and stability. This study investigates the interaction of Lycium barbarum polysaccharide (LBP) at 0–2.00 % concentrations with whey protein isolate (WPI), focusing on functionality and structural changes. LBP covalently grafted onto WPI, as confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), forming WPI-LBP complexes with a maximum degree of grafting (DG) of 44.58 % at 2.00 % LBP. This grafting reduced WPI's surface hydrophobicity (H0) and improved solubility, emulsifying properties, and digestibility under certain conditions, with optimal antioxidant activity at 1.00 % LBP. Multispectral analysis and microscopy showed LBP grafting alters WPI's secondary, tertiary, crystalline, and micro/nanostructures. The comprehensive analysis indicates that the interaction between LBP and WPI involves covalent bonding, hydrogen bonding, hydrophobic interactions, and electrostatic forces, as supported by zeta potential and chemical forces results. These findings suggest LBP-protein complexes as promising food materials for enhancing functionality and stability in the food industry.

Improved viability of probiotics by co-encapsulation of wheat germ oil under storage and gastrointestinal conditions: Effects of drying methods and wall composition

To improve the viability of probiotics during food storage and gastrointestinal digestion, this study developed solid microcapsules co-loaded with probiotics and wheat germ oil using W1/O/W2 emulsion pre-encapsulation, followed by spray drying (SD), freeze drying (FD) and spray freeze drying (SFD), respectively. The effects of drying methods and wall materials on the microstructure, physicochemical properties, storage stability, and gastrointestinal tolerability were highlighted. Firstly, all samples showed high encapsulation efficiency for probiotics (86%–99.2%) and wheat germ oil (72%–85%), low moisture content (2.8%–5.3%) and hygroscopicity (6.3%–11.6%), and wall materials exhibited structural stability during the drying process. The results of viable cell counts indicated that SFD caused more damage to bacterial cells than the other two drying methods, as evidenced by the total death of encapsulated probiotics within 90 days. In contrast, SD and FD encapsulated probiotics remained at 8.8–9.9 log CFU/g after 150 days of storage at 4 °C and 25 °C. Furthermore, the viability of probiotics in the co-encapsulated and pectin-added microcapsules was significantly enhanced in storage stability and simulated gastrointestinal digestion tests. Based on the above results, it was suggested that the co-encapsulation strategy of combining the W1/O/W2 structure and SD or FD to prepare microencapsulated powders can obtain probiotic products with high activity and high stability. Meanwhile, composite wall material (whey protein isolate and pectin) could enhance probiotics' protective effect and colonic targeted release behavior. In conclusion, the current research provides a valuable reference for the application of probiotics and functional oils in the food industry.