Whey Protein Isolate Research Articles

The formation of protein coronas and the interaction of soy protein isolate and whey protein isolate with starch nanoparticles

The influence of food components on the physicochemical properties and biological responses of nanoparticles is pivotal. Since soy protein isolate (SPI) and whey protein isolate (WPI) are commonly used as plant and animal proteins in food, it is imperative to gain comprehensive knowledge of the interaction between SPI/WPI and nanoparticles. Accordingly, we examined the adsorption of SPI and WPI onto starch nanoparticles (SNPs) and their associated interactions. SNP aggregation was observed in the SPI/WPI, and coronas formed around the surfaces of the SNPs. The binding of the protein isolates reduced the zeta potential of the SNPs from −10.34 to −26.5 mV for the SPI and to −21.37 mV for the WPI. However, mixing the SNPs with the protein isolates did not alter the microenvironment of aromatic amino acids and had no substantial impact on the secondary structure of the proteins. Thermogravimetric analysis revealed that the formation of SPI/WPI coronas enhanced the thermal stability of the SNPs. Isothermal titration calorimetry indicated that the adsorption of the SPI and WPI onto the SNPs was driven primarily by weak van der Waals forces and hydrogen bonds. This study facilitates the predicting of organic nanoparticle behaviours in complex food matrix and human gastrointestinal environments.

Improvement of the properties of essential oil-starch film with whey protein isolated fibril and sodium caseinate

Essential oil-starch films are important bioactive films, but their properties are not good enough and need improved. In this work, sodium caseinate (CAS) was utilized to improve the distribution and release of Cinnamon essential oils (CEO), and whey protein isolate fibril (WPIF) of different loadings (0 %, 4 %, 8 % and 12 %, w/w) in starch basis was added to enhance the mechanical properties of starch films. Physical, mechanical, thermal, structural, antibacterial properties, and essential oil release in the films were investigated. CAS-CEO nanoemulsion (190.7±9.4 nm) promoted the compatibility between starch and WPIF. The addition of CAS-CEO nanoemulsion and WPIF synergistically enhanced the tensile strength, stiffness, crystallinity and antibacterial effects, reduced the water vapor permeability of films, and especially delayed the release of essential oil from the films. The starch film composited with CAS-CEO nanoemulsion and appropriate loading of WPIF (8 %) significantly improved the film properties, but the addition of 12 % WPIF disrupted the properties, which might be attributed to the excessive aggregation of WPIF. The work provided useful information for improving the properties of CEO films via adding the emulsifier of CAS and the texture booster of WPIF, which could help to improve the film properties containing oil-soluble bioactive agents.

Development of homemade oral nutrition supplements for individuals with kidney failure on hemodialysis: physicochemical properties, nutrient composition, and sensory evaluation

Purpose Protein-energy wasting is a common complication among patients with kidney failure undergoing dialysis. This study aims to develop a homemade oral nutrition supplement (ONS) to fulfill the energy and protein requirements of these patients. Design/methodology/approach Three formulations of homemade ONS were developed using soybean milk, whey protein isolates and canola oil. Two of these formulations were flavored with pineapple and honeydew juices, respectively. The energy and macronutrient contents were determined using proximate analyses, and mineral contents were determined using inductively coupled plasma optical emission spectroscopy. The acceptance of homemade ONS for five attributes, namely color, taste, odor, consistency and overall acceptability, was assessed using the nine-point hedonic scale. Findings The homemade ONS provided 198–212 kcal and 8.4–9.6 g protein per 100 mL, which were comparable to commercial products. Similarly, the sodium (45–65 mg/100 mL) and phosphorus (56–66 mg/100 mL) contents were on par with commercial products. However, the potassium content of homemade ONS was higher, ranging from 141 to 155 mg per 100 mL. The sensory evaluation indicated that the formulation added with honeydew juice had a similar degree of acceptance as the commercial ONS, while formulations containing pineapple juice and without added fruit juice were less favored. Originality/value A few studies have investigated the development of food products for individuals with kidney failure on dialysis. However, to the best of the authors’ knowledge, this is the first study to focus on developing a homemade ONS specifically tailored to meet the unique nutritional needs of hemodialysis patients. In addition, this research included a comprehensive assessment of the beverage’s nutritional content and sensory attributes.

Combining the Powerful Antioxidant and Antimicrobial Activities of Pomegranate Waste Extracts with Whey Protein Coating-Forming Ability for Food Preservation Strategies

Different solvents water, ethanol and ethanol/water (6:4 v/v), were compared in the extraction of pomegranate peels and seeds (PPS) in terms of recovery yields, antioxidant properties, and antimicrobial action against typical spoilage bacterial and fungal species. The best performing extract (ethanol/water (6:4 v/v) was shown to contain mostly ellagic acid and punicalagin as phenolic compounds (5% overall) and hydrolysable tannins (16% as ellagic acid equivalents) and was able to inhibit the growth of the acidophilic Alicyclobacillus acidoterrestris at a concentration as low as 1%. The preservation of the organoleptic profile of A. acidoterrestris-inoculated apple juice with extract at 1% over 20 days was also observed thanks to the complete inhibition of bacterial growth, while the extract at 0.1% warranted a significant (40%) inhibition of the enzymatic browning of apple smoothies over the first 30 min. When incorporated in whey proteins’ isolate (WPI) at 5% w/w, the hydroalcoholic extract conferred well appreciable antioxidant properties to the resulting coating-forming hydrogel, comparable to those expected for the pure extract considering the amount present. The WPI coatings loaded with the hydroalcoholic extract at 5% were able to delay the browning of cut fruit by ca. 33% against a 22% inhibition observed with the sole WPI. In addition, the functionalized coating showed an inhibition of lipid peroxidation of Gouda cheese 2-fold higher with respect to that observed with WPI alone. These results open good perspectives toward sustainable food preservation strategies, highlighting the potential of PPS extract for the implementation of WPI-based active packaging.

Insight into Sequential Extrusion and Cysteine Treatment for Improving Rheological Characteristics and In Vitro Digestibility of Whey Protein Isolate.

The effects of sequential cold extrusion and cysteine (Cys) treatment on the rheological characteristics and in vitro digestibility of whey protein isolate (WPI) were researched in this work. Cold extrusion and Cys treatment increased the apparent viscosity, shear stress, Péclet number, and viscoelasticity of WPI. Furthermore, the emulsifying activity index enhanced in the order of WPI, Cys-treated WPI (Cys-WPI), cold-extruded WPI (CWPI), and extrusion-Cys treated WPI (Cys-CWPI). The emulsion stability index of Cys-CWPI was increased by 29.69% higher than that of WPI. Besides, the α-glucosidase inhibitory rate and xanthine oxidase inhibitory activity in the digests of Cys-CWPI were markedly increased compared with digests of WPI. The synergism of cold extrusion and Cys provides an effective approach for the application of whey protein-based thickeners and emulsifiers; meanwhile, its digestive products may assist in the development of hypoglycemic and uric acid-lowering foods.

Development of gel-like, high encapsulation efficiency and antibacterial cinnamaldehyde-loaded Pickering emulsion stabilized by EGCG enhanced whey protein isolate-gum arabic ternary nanocomplex

Pickering emulsions (PEs) loaded with essential oils have proven to be a promising delivery system in food preservation, thus attracting increasing research attention. In this study, epigallocatechin gallate (EGCG) enhanced whey protein isolate(WPI)-gum Arabic(GA) ternary spherical nanocomplex (WGE) was fabricated by thermal and pH double-induced method and used to stabilize antibacterial, antioxidant and sustained release Pickering emulsions loaded with cinnamaldehyde. The WGE nanocomplex exhibited biphasic surface wettability (78.2±2.8°), 1.73 times that of WPI, as well as outstanding interfacial tension (5.60 mN/m), 44.6 % lower than that of WPI-GA, mainly due to the electrostatic interactions between WPI and GA and enhanced surface hydrophobicity causing by EGCG, indicating its superb ability to stabilize Pickering emulsions. Using WGE nanocomplex as the Pickering emulsion stabilizer, PEs template was constructed. Confocal laser scanning microscopy (CLSM) showed the formation of a dense oil-water interface layer and gel-like network structure, which demonstrated good storage stability against creaming and coalescence, benefiting to cinnamaldehyde encapsulation. Finally, cinnamaldehyde was encapsulated effectively using this PEs pattern with high encapsulation efficiency under different conditions. The cinnamaldehyde Pickering emulsions (CPEs) demonstrated superior antioxidant ability against DPPH (>85 %) and ABTS (>78 %), as well as effective antibacterial capability against E. coli (>99.9999 %) and S. aureus (>99.99 %) than pure cinnamaldehyde. Moreover, CPEs showed slow sustained-release ability, which could satisfyingly prolong the biological activity of cinnamaldehyde. Therefore, the WGE stabilized cinnamaldehyde Pickering emulsions fabricated in this work might provide a promising alternative for the delivery of antibacterial and controlled release essential oils in the food industry.

Physicochemical Characterization of Polysaccharide–Protein Carriers with Immobilized Yeast Cells Obtained Using the Freeze-Drying Technique

New techniques for the immobilization of yeast cells have the potential for enhancement of the beer production process. Alongside conventional materials for cell immobilization, there is a rising trend toward polysaccharide–protein systems. This study focused on the immobilization of yeast cells (Saccharomyces pastorianus) via a freeze-drying process. The whey protein isolate, sodium alginate, maltodextrin, inulin, and their blends were used for carrier preparation. The effect of a 1.0% inulin solution as a cryoprotectant on the viability of the yeast cells after the freeze-drying process was also analyzed. The powders were assessed for cell viability, moisture content, water activity, solubility, particle size, and surface charge. According to the results, the addition of whey proteins reduced the moisture content, while solubility did not significantly decrease. Samples containing whey protein showed slight diameter variations. The negative surface charge observed in all samples, especially the control, indicates a cell’s tendency to aggregate, demonstrated by optical microscopy. SEM micrographs showed successful cell immobilization in polysaccharide–protein carriers. Furthermore, inulin and whey protein addition enhanced cell protection during the immobilization of cells. The freeze-drying technique demonstrates efficacy in immobilization of yeast cells, indicating its potential for applications in the food and beverage industry.

Effects of mono- and dual-frequency ultrasounds on structure and physicochemical properties of faba bean proteins

Faba bean proteins are currently viewed as promising animal protein alternatives. However, certain functional properties e.g. relatively low solubility compared to whey protein isolates, can limit the application of faba bean protein isolates (FPIs) in certain food products. Therefore, it may be desirable to use modification approaches such as the application of ultrasound to alter such limiting physicochemical properties. In this study, Faba Bean Protein Isolates (FPIs) were treated by ultrasound with different frequencies (20 kHz, 40 kHz and 20 + 40 kHz) prior to hydration (1 %) at different pH levels (3, 7, and 9). Then the structure and physicochemical properties (i.e. particle size, ζ-potential, surface hydrophobicity, thermal behavior, and solubility) of control and untreated FPIs were investigated. Ultrasound treatment had no obvious effect on the molecular weight of FPIs, whereas it changed the secondary structure of FPIs from a more ordered structure to a more disordered structure. The applied treatment resulted in an increase in surface hydrophobicity across all treatment levels and pHs. It also decreased the particle size of FPI at pH 3, while it increased the particle size at pH 7 and 9, compared to the untreated FPI. In addition, the solubility and thermal properties of FPI were modified through the ultrasound treatment. The higher solubility of FPI could improve its potential to be used as a functional ingredient for many food applications. Ultrasound treatment at 20 kHz and 20 + 40 kHz had more effects on the physiochemical properties of FPI compared to that at 40 kHz. Overall, ultrasound treatment with different frequencies (20 kHz, 40 kHz, and 20 + 40 kHz) modified the structure and physiochemical properties of FPI to different degrees and may be beneficial for the development of FPI for certain food applications.

Whey protein-based bigels for co-encapsulation of curcumin and gallic acid: Characterization, stability and release kinetics

Bigels are a class of soft matter systems with great promise for the food industry as food analogs or as enhanced ingredient substitutes. This work aimed to improve the curcumin (CUR) and gallic-acid (GA) stability, antioxidant capabilities, and controlled release by co-encapsulating them within bigels. This delivery system included a bigel made by whey protein isolate (WPI) aggregates-based oleogel and WPI-based hydrogel in equivalent amounts (50:50). The following techniques were used to evaluate how different bigels affected the chemical stability of CUR and GA: X-ray diffraction (XRD), thermogravimetric analysis (TGA), 1H-nuclear magnetic resonance (1H-NMR), and Fourier infrared (FTIR) spectroscopy. As a result of the protein's ligand-binding abilities, some components may co-adsorb to oil droplet surfaces. Next, it was determined how well the bigels performed as a carrier and looked at their physicochemical stability, digestion, and performance. Examining the release rate of CUR and GA during digestion showed that bigel had a slower release rate (6–15%) than oleogel (16%) and hydrogel (34%), and CUR had a lower release (50%) due to its higher molecular weight and greater entanglement than GA (70%). The stability of bigel (against heat and light) was also higher than oleogel and hydrogel due to having a higher solid component that requires more stress to be applied to the system. CUR and GA had more antioxidant activity in bigel (96.24%) than oleogel (77.71%) and hydrogel (77.34%); which can be attributed to the formation of ultra-fine colloidal dispersions by bigel, allowing more CUR and GA to interact with free radicals by creating more contact surface. The multi-functional bigels showed great potential for delivering antioxidants to the intestine while enhancing their stability. Hydrophobic interactions and hydrogen bonding between WPI and CUR-GA were validated by FTIR analysis, that kept bigels stable. Overall, our findings demonstrated that WPI-based bigels with intriguing UV light, color, and thermal stability could be developed. This would increase the use of bigels in innovative food products with high nutritional value.

Exploring the Nexus Between Emulsifier Characteristics and Salmonella Typhimurium Viability in Oil‐in‐Water Emulsions

ABSTRACTMolecular characteristics of emulsifiers such as their molecular weight (MW) and surface charge, not only affect the stability of the emulsion but also can have an impact on its capacity to either inhibit or promote microbial proliferation. These characteristics can affect the behavior of pathogens such as Salmonella Typhimurium in emulsion systems. The growth and thermal resistance of S. Typhimurium were monitored at different oil content levels (20%, 40%, and 60%) in emulsions stabilized by three whey protein‐based emulsifiers: whey protein isolate (WPI), whey protein hydrolysate (WPH), and a modified WPI with an alteration of charge (WPI+). Our study revealed that emulsifier itself with different MW and surface charge had no effect on bacterial growth and inactivation without oil inclusion (p > 0.05). However, it was found that higher bacterial growth rate at 60% oil content emulsion stabilized with WPI+ (0.65 ± 0.03 log CFU/h) than WPI (0.19 ± 0.04 log CFU/h), which showed the charge of emulsifiers has different effects on microbial dynamics in oil‐in‐water emulsion. Interestingly, WPI+ in emulsions also seemed to convey protection against thermal inactivation of bacteria. These data describe a complex interrelationship between the physicochemical characteristics of the emulsifier and its interacting nature with bacterial cells. They throw even more light on the insight about the importance of a strategic approach toward emulsifier selection in food formulations. This is crucial for the food safety and stability of products.

Fabrication and optimization of ultra-long stable microencapsulated chlorophyll using combinations of wall material via response surface methodology

Nowadays, the need to use natural pigments instead of artificial colorants in food has increased due to health risks. Chlorophyll is a natural colorant with antioxidant properties. Chlorophyll is a natural pigment with superior antioxidant properties. However, this pigment is unstable in the different conditions of food processing. To increase the stability of chlorophyll extracted from Ulva intestinalis algae, encapsulation of chlorophyll with maltodextrin (MD) and whey protein isolate (WPI) carriers by two drying methods including spray drying and freeze drying was achieved. The optimum combination of wall and core materials to achieve the highest response including encapsulation efficiency (EE) and chlorophyll content (CC) was obtained by response surface methodology and central composite design. The optimal chlorophyll microcapsule (Chl-M) obtained was chosen for subsequent tests containing solubility, moisture content, and antioxidant properties. The results showed that the highest EE and CC were 90.27 ± 0.21%, 55.36 ± 0.36 μg/mL, and 90.46 ± 0.62%, 85.85 ± 0.43 μg/mL, respectively in SD and FD. The microcapsules produced by the freeze dryer (FD) had higher antioxidant activity (79.1 ± 0.24) than the microcapsules produced by the spray dryer (SD) (67.5 ± 0.16). The highest solubility (95.32%) and the lowest moisture content (3.7 ± 0.05) were related to the SD. Freeze drying method (FDM) had the highest EE (91.2%), CC (89.67 μg/mL), and antioxidant properties (79.1%). It is hoped that the encapsulated chlorophyll can be used as a health-promoting food color additive in the food industry.

Incorporating functional colorants in whey protein isolate–cellulose nanocrystal-blended edible films for pork freshness prediction

In this study, intelligent pH- and ammonia-sensing edible films are designed based on whey protein isolate (WPI)–cellulose nanocrystal-based biopolymers by incorporating different functional colorants (curcumin, phycocyanin, and modified lycopene), alone and paired, to promote food freshness and monitoring efforts. Incorporating the colorants endowed the films were endowed with pH- and ammonia-responsiveness and enhanced UV-blocking, antioxidant, and antibacterial capabilities. Phycocyanin induces WPI unfolding, increasing the accessibility of curcumin; hence, combining curcumin with phycocyanin promotes the sensitivity of films to pH and NH3 compared with those containing a single colorant. In the pork freshness monitoring analysis, the combined-colorants film underwent a noticeable color change as the meat spoiled. Moreover, the meat packaged with the combined film exhibited lower levels of lipid oxidation than those packaged in single-colorant films. These results suggest that curcumin–phycocyanin-containing films have multifunctional potential in intelligent food packaging.

Characterization and kinetics of whey protein isolate amyloid fibril aggregates under moderate electric fields

Food proteins solutions enable the controlled flow of electrical current when subjected to a Moderate electric field (MEF). This application results in internal heat generation, known as ohmic heating, accompanied by electrochemical reactions. These effects play a significant role in influencing the formation of protein amyloid fibril aggregates (AFA), which have broad applications in food and biomedical fields, ranging from improving food texture to biomedical applications such as drug delivery and disease treatment. This study focused on investigating the formation of β-Lactoglobulin (β-lg) AFA under MEF conditions using WPI as protein source and various characterization techniques (e.g., Thioflavin T fluorescence, circular dichroism, and electron microscopy). The results indicated that MEF prolonged the lag phase of AFA formation. Furthermore, nucleation and fibril growth showed higher activation coefficients and cooperativity level (n > 2) compared to conventional heating method. MEF treatment resulted in unique fibril clustering and the presence of unexpected higher-order AFA networks confirmed by electron microscopy. These findings highlight the significant role of MEF in influencing the aggregation kinetics of β-lg AFA. Exploring further into the electrochemical and thermal effects during protein aggregation processes holds the key to unlocking deeper insights fibril formation process.

Effect of dynamic high-pressure microfluidization on the structural, emulsifying properties, in vitro digestion and antioxidant activity of whey protein isolate

Effect of dynamic high-pressure microfluidization on the structural, emulsifying properties, in vitro digestion and antioxidant activity of whey protein isolate

Regulation on Aggregation Behavior and In Vitro Digestibility of Phytic Acid-Whey Protein Isolate Complexes: Effects of Heating, pH and Phytic Acid Levels.

The impact of heat treatment, pH and phytic acid (PA) concentration on the aggregation behavior and digestibility of whey protein isolate (WPI) was investigated. The experimental results indicated that below the isoelectric point of WPI, heat treatment and elevated PA levels significantly increased turbidity and particle size, leading to the aggregation of WPI molecules. No new chemical bonds were formed and the thermodynamic parameters ΔH < 0, ΔS > 0 and ΔG < 0 suggested that the interaction between PA and WPI was primarily a spontaneous electrostatic interaction driven by enthalpy. After the small intestine stage, increasing phytic acid levels resulted in a significant decrease in hydrolysis degree from 16.2 ± 1.5% (PA0) to 10.9 ± 1.4% (0.5% PA). Conversely, above isoelectric point of WPI, there was no significant correlation between the presence of PA and the aggregation behavior or digestion characteristics of WPI. These results were attributed to steric hindrance caused by PA-WPI condensates, which prevented protease binding to hydrolysis sites on WPI. In summary, the effect of PA on protein aggregation behavior and digestive characteristics was not simply dependent on its presence but largely on the aggregation degree of PA-WPI induced by heat treatment, pH and PA concentration. The findings obtained here suggested that phytic acid may be utilized as an agent to modulate the digestion characteristics of proteins according to production requirements. Additionally, the agglomerates formed by heating phytic acid and protein below the isoelectric point could also be utilized for nutrient delivery.

Study on stability and in vitro digestion property of Lutein Pickering emulsions encapsulated with whey protein isolate /sodium alginate/tea polyphenols

Study on stability and in vitro digestion property of Lutein Pickering emulsions encapsulated with whey protein isolate /sodium alginate/tea polyphenols

In vitro digestive behavior of emulsifier-stabilized excipient emulsions affects the bioaccessibility of flavonoids.

Flavonoids, found in common vegetables and fruits, have health benefits that are often limited by their low bioavailability. Excipient emulsions provide an effective strategy to overcome these obstacles. However, the nature of the emulsifier used to formulate excipient emulsions and the chemical structure of the flavonoids both affect the bioaccessibility of the flavonoids. The purpose of this study was to investigate the impact of the interfacial properties of excipient emulsions on the in vitro gastrointestinal fate of representative structural flavonoids (quercetin, kaempferol, and apigenin) through the INFOGEST method. Tween 80 (TW80) (a nonionic surfactant) was more effective at reducing the oil-water interfacial tension than whey protein isolate (WPI) (a protein-based emulsifier) or octenyl succinic anhydride (OSA)-modified starch (MS) (a polysaccharide-based emulsifier). Moreover, TW80 created excipient emulsions with smaller oil droplets, which were more resistant to oral and gastric conditions. The WPI-emulsions underwent severe flocculation in the gastric phase, leading to an appreciable increase in particle size (from 220 to 3000 nm). The TW80-coated oil droplets were more digestible than WPI- or MS-coated ones. This was attributed to the larger lipid surface area for lipase attachment. The bioaccessibility of quercetin, kaempferol, and apigenin was also affected by emulsifiers: TW 80 (25% to 45%) > WPI (14% to 29%) ≈ MS (15% to 25%). Flavonoid bioaccessibility appeared to be related to their molecular properties. This study provides guidance for the design of effective excipient emulsions to enhance the bioavailability of flavonoids. © 2024 Society of Chemical Industry.

Unveiling the slow digestion and peptide profiles of polymerised whey gel via heat and TGase crosslinking: An in vitro/vivo perspective

Polymerised whey is widely used in dairy products and can affect digestibility when its high-molecular-weight aggregates and gel structure are modified. This study investigated the digestibility, peptide profiles and satiety of modified whey protein isolate (MWPI) pre-heated with transglutaminase. Results showed that 43.06 % of MWPI was digested during the 4-h in vitro digestion, indicating a slow digestion rate. Compared with whey protein isolate (WPI), MWPI yielded 103 peptides with higher abundance following in vitro digestion, including 17 angiotensin-converting enzyme inhibitors and 1 dipeptidyl peptidase-4 inhibitor. Visual analytics indicated differential peptides located at distinct α-helix and β-sheet of β-lactoglobulin, α-lactalbumin and bovine serum albumin. MWPI gavage extended stomach retention time, decreased intestinal propulsion rate from 75.60 % (WPI group) to 33.72 % in 30 min and enhanced satiety within 120 min compared with WPI. Overall, whey polymerisation modulates protein–enzyme interactions, releasing different peptides and enhancing satiety.

Amyloid fibrils for β-carotene delivery – Influence of self-assembled structures on binding and in vitro release behavior

Two whey protein isolate amyloid fibrils (WPIF) with different structure were prepared, and the effects of these structures on binding of β-carotene (BC) and in vitro digestibility were evaluated. Whey protein isolate (WPI) in water (80 °C, pH 2.0) self-assembled into elongated WPIF (E-WPIF), whereas WPI formed to worm-like WPIF (W-WPIF) in trifluoroethanol. Compared to E-WPIF, W-WPIF showed higher surface hydrophobicity, indicating exposure of more hydrophobic residues. The encapsulation efficiency and loading capacity of BC in W-WPIF were higher than that of E-WPIF. The hydrophobic interaction were the main driving forces of WPIF/BC. During gastric digestion, WPIF lost intact fibrils structures, resulting in unordered small aggregates and most BC still bound to them. Then they were destroyed in the following intestinal digestion, leading to the release of BC. Compared with W-WPIF/BC, E-WPIF/BC had higher release of BC in gastrointestinal digestion due to weaker binding of BC and better digestibility of E-WPIF.

Probiotic Milk and Oat Beverages with Increased Protein Content: Survival of Probiotic Bacteria Under Simulated In Vitro Digestion Conditions.

The increasing prevalence of plant-based dietary preferences, driven by lactose intolerance, allergies, and adherence to vegan diets, has necessitated the exploration of alternative food matrices for probiotic delivery. This study aimed to evaluate the effects of whey protein isolate, pea protein isolate, and soy protein isolate on the viability of L. casei and L. johnsonii during simulated in vitro gastrointestinal digestion. Furthermore, the study investigated the impact of two distinct matrices-cow's milk and an oat-based beverage-on the survival of these probiotic strains. Fermented products were prepared using cow's milk and an oat-based beverage as matrices, with simulated digestion performed following a seven-day storage period at 5 °C. The in vitro digestion model encompassed oral, gastric, and small intestinal phases, with probiotic viability assessed using the plate-deep method at each stage. Before digestion, L. casei exhibited higher populations than L. johnsonii in both matrices. Including 3% soy and pea protein, isolates promoted the growth of L. casei in both fermented milk and oat beverages. However, a marked reduction in probiotic viability was observed during the gastric phase, with L. casei counts decreasing by 6.4-7.8 log cfu g-1 in fermented milk and 3.1-4 log cfu g-1 in oat beverages, while L. johnsonii demonstrated similar reductions. These findings underscore the protective role of dairy components on probiotic viability, while the oat-based matrix exhibited a reduced capacity for sustaining probiotic populations throughout digestion. Future research should focus on optimizing plant-based matrices to enhance probiotic stability during gastrointestinal transit.