Functionality Of Whey Proteins Research Articles

Effects of spray drying and freeze drying on the protein profile of whey protein concentrate.

Whey protein concentrate (WPC) is consumed for its high protein content. The structure and biological functionality of whey proteins in WPC powders may be affected by the drying technique applied. However, the specific impact of spray drying and freeze drying on the overall protein profile of whey protein derived from sweet whey streams at scale is unknown. Herein, we examine the effects of commercial-scale freeze drying and spray drying on WPC to determine which method better preserves bioactive whey proteins, with the goal of helping the dairy industry create high-value products that meet the growing consumer demand for functional dairy products. WPCs were produced from pasteurized liquid whey using either a commercial spray dryer or freeze dryer. A variety of analytical techniques, including enzyme-linked immunosorbent assay, polyacrylamide gel electrophoresis, and bottom-up proteomics using liquid chromatography-tandem mass spectroscopy were used to identify, quantify, and compare the retention of bioactive proteins in WPC before and after spray drying and freeze drying. In addition, the extent of denaturation was studied via solubility testing, differential scanning calorimetry, and hydrophobicity assessment. There was little to no difference in the retention or denaturation of key bioactive proteins between spray-dried and freeze-dried WPC powders. There was a higher percentage of select Maillard modifications in freeze-dried and spray-dried powders than in the control. The lack of significant differences between spray drying and freeze drying identified herein indicates that freeze drying does not meaningfully improve retention of bioactive proteins compared with spray drying when performed after multiple pasteurization steps. PRACTICAL APPLICATION: This study aimed to provide insight into the impacts of spray drying versus freeze drying on whey proteins. Overall, our results indicate that for commercial dairy processing that involves multiple rounds of pasteurization, freeze drying does not meaningfully improve the retention of bioactive proteins compared with spray drying. These findings may help the food and dairy industry make informed decisions regarding the processing of its whey protein products to optimize nutritional value.

Structure and functionality of whey protein, pea protein, and mixed whey and pea proteins treated by pH shift or high-intensity ultrasound

Three modifications (pH shift, ultrasound, combined pH shift and ultrasound) induced alterations in pure whey protein isolate (WPI), pea protein isolate (PPI), and mixed whey and pea protein (WPI-PPI) were investigated. The processing effect was related to the protein type and technique used. Solubility of WPI remained unchanged by various treatments. Particle size was enlarged by pH shift while reduced by ultrasound and combined approach. All methods exposed more surface hydrophobic groups on WPI, while pH shift and joint processing was detrimental to its emulsifying activity. The PPI and mixture exhibited similar responses toward the modifications. Solubility of PPI and the blend enhanced in the sequence of pH shift and ultrasound > ultrasound > pH shift. Individual approach expanded while co-handling diminished the particle diameter. Treatments also caused more disclosure of hydrophobic regions in PPI and WPI-PPI and emulsifying activity was ameliorated in the order of pH shift and ultrasound > ultrasound > pH shift.

Impacts of hesperidin on whey protein functionality: Interacting mechanism, antioxidant capacity, and emulsion stabilizing effects.

The objective of this work was to explore the possibility of improving the antioxidant capacity and application of whey protein (WP) through non-covalent interactions with hesperidin (HES), a citrus polyphenol with nutraceutical activity. The interaction mechanism was elucidated using several spectroscopic methods and molecular docking analysis. The antioxidant capacity of the WP-HES complexes was analyzed and compared to that of the proteins alone. Moreover, the resistance of oil-in-water emulsions formulated using the WP-HES complexes as antioxidant emulsifiers to changes in environmental conditions (pH, ion strength, and oxidant) was evaluated. Our results showed that HES was incorporated into a single hydrophobic cavity in the WP molecule, where it was mainly held by hydrophobic attractive forces. As a result, the microenvironments of the non-polar tyrosine and tryptophan residues in the protein molecules were altered after complexation. Moreover, the α-helix and β-sheet regions in the protein decreased after complexation, while the β-turn and random regions increased. The antioxidant capacity of the WP-HES complexes was greater than that of the proteins alone. Non-radiative energy transfer from WP to HES was detected during complex formation. Compared to WP alone, the WP-HES complexes produced emulsions with smaller mean droplet diameters, exhibited higher pH and salt stability, and had better oxidative stability. The magnitude of these effects increased as the HES concentration was increased. This research would supply valuable information on the nature of the interactions between WP and HES. Moreover, it may lead to the creation of dual-function antioxidant emulsifiers for application in emulsified food products.

Changes in conformation and functionality of whey proteins induced by the interactions with soy isoflavones

Modification of food proteins by interactions with polyphenols has been used to improve the functional properties of proteins. In this study, soy isoflavones-whey protein complexes were prepared via non-covalent complexation. Solubility of soy isoflavones and changes in conformation and functionality of whey proteins were investigated. The results showed that the solubility of soy isoflavones was significantly increased by the complexation with whey proteins (p < 0.05). Soy isoflavones induced decreased α-helix and increased β-sheet of whey protein but increased α-helix and decreased β-sheet of polymerized whey protein. The solubility, foaming properties, and emulsifying activity of whey proteins were enhanced. The thermal stability of whey protein was decreased, but the thermal stability of polymerized whey protein was increased. The thermal gelation behavior of whey protein was enhanced. This study demonstrated that the conformation and functionality of whey proteins could be modified by interaction with soy isoflavones. There were some different changes in the functionalities of whey protein and polymerized whey protein due to the diverse conformation changes. The current study may provide useful information for the modification of whey proteins by polyphenols complexation.

Whey protein isolate-low acyl gellan gum Maillard-based conjugates with tailored technological functionality and antioxidant activity

Whey proteins are usually sensitive to ionic strength, pH change, and heat treatment, which may affect their functional properties. Maillard conjugation could be a facile approach to improve whey protein functionality. In this study, whey protein isolate (WPI; 0.6%, w/v) was conjugated to low acyl gellan gum (0.1, 0.2, and 0.3%, w/v) through the Maillard reaction at 90 °C for 90 min. The conjugate formation was confirmed by pH decrement, glycation degree (up to 9.44%), browning index, sodium dodecyl sulphate-polyacrylamide gel electrophoresis, and Fourier transform infrared spectroscopy. The surface hydrophobicity of WPI increased up to 2-fold upon conjugation, which led to a solubility decrease. However, the conjugated WPI had an improved interfacial activity, emulsifying activity (∼6%), foaming capacity (up to 63.64%), thickening ability (up to 24.67-fold), reducing power (up to 28.86-fold), and iron chelating activity (up to 3.31-fold). These findings may widen the industrial application of whey proteins.

Effect of Fructus Mori. bioactive polysaccharide conjugation on improving functional and antioxidant activity of whey protein

Whey protein with high biological and technological values is an excellent source of nutrition. However, the limited functional properties prevent its widespread applications in food industry. In this study, the whey protein functionality was improved via glycation with mulberry fruit polysaccharide by Maillard reaction. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile and free amino groups determination confirmed the glycation occurred between whey protein and mulberry fruit polysaccharide. The emulsion capacity and stability of the conjugates were 1.40-fold and 1.52-fold higher than that of whey protein. The conjugates also exhibited remarkably improved antioxidant activity. The fish oil emulsion coated by conjugates demonstrated smaller droplet size, better storage and oxidative stability than that stabilized by whey protein. The findings would be of vital importance for updated understanding of the modification in emulsifying properties of proteins by glycation with natural bioactive polysaccharides as well as for the development of healthy foods.

Enhanced stability of emulsions made with super‐critical carbon dioxide extruded whey protein concentrate

AbstractSupercritical fluid extrusion (SCFX) with carbon dioxide was used to enhance the functionality of whey protein concentrate containing 80% protein by weight (WPC80) at two (3.0 and 5.4) pH values. Different levels of oil (20, 40, 60, and 80% by weight) and functionalized whey protein (f‐WPC80; 1, 2, and 4% by weight) were used to make emulsions and quantify their characteristics such as emulsion activity index, creaming index, droplet size, and viscosity. Unextruded whey protein (c‐WPC80) and commercial sodium caseinate (NaCas) were used as controls. Results showed that gel‐like emulsions with uniform droplet size distributions were formed by f‐WPC80 (4% by weight) with 80% (by weight) oil which was stable over 3 months of storage at room temperature. Compared to emulsions formed by control c‐WPC80, the f‐WPC80 emulsions exhibited higher viscosity and shear thinning behavior. The minimum protein required for stable emulsion formation (with 80% oil) was found to be 2% by weight for f‐WPC80 and NaCas and 4% by weight in the case of c‐WPC80. The functionalized whey protein provided a better emulsion at low concentrations with good stability at room temperature and may be used as a replacement of sodium caseinate to make nutritionally superior products.Practical applicationsPresent study showed that functionalized Whey protein concentrate (80% protein) f‐WPC80 was produced by the process of Supercritical carbon dioxide assisted extrusion which changed the structure of native protein. Two functionalized products (with pH 3.0 and 5.4) were obtained in this way. These functionalized proteins formed better oil‐in‐water emulsions which were stable against creaming and sedimentation as compared to emulsions stabilized by native WPC80 and sodium caseinate at very small concentration of protein used. Therefore it is concluded that f‐WPC80 can cover a range of food emulsions where different pH values are required. Lesser amount of stabilizer will be used commercially for emulsions. These functionalized WPC80 products may be used as a replacement of sodium caseinate to make nutritionally superior products with pH 3.0 and 5.4.

Influence of the Maillard reaction on the properties of cold-set whey protein and maltodextrin binary gels

The Maillard conjugation of proteins and reducing saccharides is used to modify the technological functionality of whey proteins. In this study, whey protein isolate (WPI) was conjugated with maltodextrin (at 1:1 ratio and two total solid contents of 100 and 200 mg mL−1) through the Maillard reaction and used to form cold-set gels. The glycation reaction increased the strength of hydrogen bonding of whey proteins and preferentially modified α-lactalbumin, in comparison with β-lactoglobulin. It also increased the reducing power of binary protein-saccharide solution and allowed formation of self-standing cold-set WPI gel at a low protein content (i.e., ≈50 mg mL−1). Microscopic imaging showed micro-phase separated maltodextrin domains, interrupting the protein network, in gels made of protein-maltodextrin physical mixtures, whereas Maillard conjugation resulted in more homogenous microstructures at both total solid contents. The Maillard reaction increased gel firmness and water-holding capacity and caused a reduction in the extent of gel swelling.

Functionality of whey proteins covalently modified by allyl isothiocyanate. Part 2: Influence of the protein modification on the surface activity in an O/W system

Allyl isothiocyanate (AITC) is a small electrophilic molecule which can be found in cabbage after degradation of glucosinolates. The covalent attachment of AITC to whey protein isolate (WPI) was previously reported to increase their hydrophobicity and structural flexibility at acidic pH values. It is thus hypothesized, that the o/w interface adsorption behaviour and interfacial structure will be altered. To further understand the effect of the AITC-modification on the emulsifying capacity, adsorption kinetic and interfacial properties of unmodified and modified WPI were investigated at the o/w interface.The WPI-modification resulted in a significantly increased surface adsorption kinetic and a lower equilibrium interfacial tension at acidic pH values. The ratio of α-lactalbumin (ALA) and β-lactoglobulin (BLG) at the oil droplet surface differed between unmodified and modified WPI (modBLG > ALA+modALA). Several layers of loosely attached proteins were evident on the oil droplet surface in all modified WPI emulsions. The hyperfine coupling (aN) of the EPR spin probe TB residing at the oil droplet surface reflected an increased hydrophobicity of the modified proteins. A lower order parameter (S) in the lipid phase of the modified WPI emulsions gave evidence of an altered alignment of the modified proteins at the interface, probably sticking into the oil phase.In conclusion, the present results indicate that the increased flexibility and hydrophobicity of the modified whey proteins, especially of modified BLG, surpass the surface activity of unmodified ALA in acidic pH values.

The effect of bleaching agents on the degradation of vitamins and carotenoids in spray-dried whey protein concentrate

Previous research has shown that bleaching affects flavor and functionality of whey proteins. The role of different bleaching agents on vitamin and carotenoid degradation is unknown. The objective of this study was to determine the effects of bleaching whey with traditional annatto (norbixin) by hydrogen peroxide (HP), benzoyl peroxide (BP), or native lactoperoxidase (LP) on vitamin and carotenoid degradation in spray-dried whey protein concentrate 80% protein (WPC80). An alternative colorant was also evaluated. Cheddar whey colored with annatto (15 mL/454 L of milk) was manufactured, pasteurized, and fat separated and then assigned to bleaching treatments of 250 mg/kg HP, 50 mg/kg BP, or 20 mg/kg HP (LP system) at 50°C for 1 h. In addition to a control (whey with norbixin, whey from cheese milk with an alternative colorant (AltC) was evaluated. The control and AltC wheys were also heated to 50°C for 1 h. Wheys were concentrated to 80% protein by ultrafiltration and spray dried. The experiment was replicated in triplicate. Samples were taken after initial milk pasteurization, initial whey formation, after fat separation, after whey pasteurization, after bleaching, and after spray drying for vitamin and carotenoid analyses. Concentrations of retinol, a-tocopherol, water-soluble vitamins, norbixin, and other carotenoids were determined by HPLC, and volatile compounds were measured by gas chromatography-mass spectrometry. Sensory attributes of the rehydrated WPC80 were documented by a trained panel. After chemical or enzymatic bleaching, WPC80 displayed 7.0 to 33.3% reductions in retinol, β-carotene, ascorbic acid, thiamin, α-carotene, and α-tocopherol. The WPC80 bleached with BP contained significantly less of these compounds than the HP- or LP-bleached WPC80. Riboflavin, pantothenic acid, pyridoxine, nicotinic acid, and cobalamin concentrations in fluid whey were not affected by bleaching. Fat-soluble vitamins were reduced in all wheys by more than 90% following curd formation and fat separation. With the exception of cobalamin and ascorbic acid, water-soluble vitamins were reduced by less than 20% throughout processing. Norbixin destruction, volatile compound, and sensory results were consistent with previous studies on bleached WPC80. The WPC80 colored with AltC had a similar sensory profile, volatile compound profile, and vitamin concentration as the control WPC80.

Functionality of whey proteins covalently modified by allyl isothiocyanate. Part 1 physicochemical and antibacterial properties of native and modified whey proteins at pH 2 to 7

Whey protein isolate (WPI) (∼75% β-lactoglobulin (β-LG)) is frequently used in foods as a natural emulsifying agent. However, at an acidic pH value, its emulsification capacity is greatly reduced. The covalent attachment of natural electrophilic hydrophobic molecules to WPI proteins is a promising method for changing the physicochemical properties of WPI in favor of a higher functionality at acidic pH values.In the present study, different concentrations of allyl isothiocyanate (AITC) were covalently bound to WPI and the related changes in physicochemical properties (charge, aggregation, surface hydrophobicity and secondary structure) were monitored over a wide pH range (pH 2 to 7). In addition, the antibacterial activity against different strains of S. aureus and E. coli before and after AITC modification was assessed.The results showed that both whey proteins β-LG and α-lactalbumin (ALA) were modified by AITC. This modification remained stable during pH adjustment. Unbound AITC was successfully removed by the lyophilization process, which reduced the strong odor of the volatile AITC. A shift of the isoelectric point towards acidic conditions was observed. The hydrophobicity of the modified WPI increased significantly and the protein's secondary and tertiary structure was altered. In addition, a more loose protein folding was observed. These effects were less pronounced at pH 6 and 7. The relatively mild antibacterial effect of native WPI was not significantly influenced by the addition of AITC.

ДОСЛІДЖЕННЯ ФЕРМЕНТНОГО ПРЕПАРАТУ ТРАНСГЛЮТАМІНАЗИ НА МОДЕЛЬНИХ ЗРАЗКАХ РЕСТРУКТУРОВАНИХ ШИНОК З ЯЛОВИЧИНИ

Науково-практичне рішення проблеми перетворення реструктурованої м’ясної системи до теплової обробки з отриманням структурних якостей цільном’язової тканини є актуальною задачею розвитку сучасної технології як науки про м'ясо. При вивченні даної проблеми найкращий результат був досягнутий при використанні ферментних препаратів, і в першу чергу ферменту трансглютамінази. Мікробіальна трансглютаміназа в кількості 0,075% забезпечує реструктурованим продуктам монолітність і покращує здатність їх до нарізання. Проведені раніше наукові дослідження підтвердили той факт, що трансглютаміназа також здатна підвищувати функціональність сироваткових білків у продуктах із подрібненого м’яса. Для досліджень були виготовлені дослідні зразки реструктурованих шинок з яловичини 1 сорту із заміною м’ясної сировини 3,0; 4,5; 6,0; 7,5% гідратованим білковим препаратом «Drip free cas». Раціональною кількістю, що сприяє покращенню структурно-механічних характеристик реструктурованих шинок, є внесення 0,075% трансглютамінази та 0,15% харчових фосфатів при заміні 6% м’ясної сировини сироватковим білковим препаратом «Drip free cas». Проведені дослідження підтвердили той факт, що розчини 0,065%, 0,075% та 0,085% трансглютамінази проявляють буферні властивості та стабілізують значення рН модельних м’ясних систем в процесі масажування, підвищують вологозв’язуючу здатність, а внесення трансглютамінази в кількості 0,075% сприяє збільшенню напруги різання дослідних зразків шинок на 7,7% у порівнянні із зразками, які містять 0,065% фермента.&#x0D;

Changes in functionality of whey protein and micellar casein after high pressure – low temperature treatments

Changes in functional properties of micellar caseins (MC) and whey proteins (WPI) due to high pressure – low temperature (HPLT) treatments were investigated and compared to changes induced via high pressure treatments at room temperature (HP). Single whey protein solutions, micellar casein dispersions and two mixtures (micellar caseins:whey proteins weight mixing ratios 80:20 and 20:80) were treated at a concentration of 2% (w/w) and at two different pH values (7.0 and 5.8). Oscillating pendant drop and shear experiments were performed to identify changes in the rheological behavior at the air/water interface and in bulk, respectively. Foaming and emulsification experiments were conducted to investigate further impacts on the functional behavior. Both, HPLT and HP treatments led to a decreased emulsion stability for emulsions from WPI solutions independent from the treatment pH, while the foam stability was increased for these samples. In comparison, the changes for MC dispersions exhibited the same tendency but less pronounced. HPLT treatments of MC rich samples always led to the formation of a few very large flocs which had a major influence on the functional behavior. The rheological behavior of these samples changed from a Newtonian to a shear-thickening behavior. The elastic part of the surface dilatational modulus was increased for a pure WPI solution after HPLT and HP treatments while the viscous part remained unaffected. However, changes in functional properties highly depended on the sample composition and results for mixtures differ from those for pure dispersions.

Combined effect of heat treatment and ionic strength on the functionality of whey proteins

A 5% (wt/vol) whey protein isolate (WPI) dispersion (pH 6.5) with different concentrations of NaCl was submitted to dynamic heat treatment. Protein dispersions were characterized as to their rheological properties, particle sizes, morphology, denaturation temperatures, and protein surface hydrophobicity. At low ionic strength (<200mmol/kg), gel elastic modulus increased and strongest gel stiffness was achieved. High salt concentrations lead to a weaker gel, whereas no gels at all were formed without salt. The gelation temperature was also influenced by ionic strength and an increase in denaturation temperature and thermal stability was also observed by using differential scanning calorimetry. Additionally, heat-induced changes in secondary structures upon salt augmentation were followed by Fourier transform infrared spectroscopy. Secondary structural elements estimations obtained from amide I assignments were correlated with those from amide III assignments. Upon salt increase, no differences in secondary structure were observed without heating, whereas upon heating and without salt increase, the Fourier transform infrared spectroscopy data revealed an increase in intermolecular β-sheets at the cost of β-turns and random coils, with no change in α-helical structures. However, NaCl addition along with dynamic heat treatment of WPI dispersion showed a stabilizing effect on the secondary structural elements of both amide I and amide III bands. Whey protein isolate dispersions in water were also characterized by transmission electron microscopy by a spherical shape with 2 populations (6 and 70nm). Salt increase alone resulted in the formation of denser aggregates, whereas a transition from spherical/compact protein aggregates to linear ones was observed due to combined salt/heat effect. The important size of these edifices was confirmed by microscopy and light-scattering techniques. Moreover, protein surface hydrophobicity related to the number of hydrophobic sites available decreased significantly. Finally, experimental results demonstrated the strong interaction between ionic strength and dynamic thermal treatment on protein functional properties and their careful adjustment could enable the food industry to effectively use WPI as a gelling agent.

Hydroxyl Radical-Stressed Whey Protein Isolate: Functional and Rheological Properties

The objective of the study was to examine the sensitivity of whey protein functionality to oxidizing radicals. Whey protein isolate (WPI) was oxidatively stressed by incubation at 20 °C for 3, 5, and 10 h in hydroxyl radical-generating media containing 0.1 mM ascorbic acid, 0.1 mM FeCl3, and 1–10 mM H2O2. Protein solubility decreased (P < 0.05) with increasing H2O2 concentrations and oxidation time. Surface properties of WPI, including both emulsifying and foaming activities, exhibited significant improvements (P < 0.05) at H2O2 concentrations up to 5 mM and oxidation time up to 5 h. The longer oxidation time or higher H2O2 concentrations tended to diminish the surface functionality. However, the oxidative stress, though decreasing the onset gelling temperature, had a general detrimental effect on WPI gelation (hardness, springiness, and storage modulus). The results indicated opposing effects of oxidation on WPI: detrimental to hydrodynamic properties (solubility, gelation) but beneficial to surface properties (emulsification, foaming).

The effect of starter culture and annatto on the flavor and functionality of whey protein concentrate

The flavor of whey protein can carry over into ingredient applications and negatively influence consumer acceptance. Understanding sources of flavors in whey protein is crucial to minimize flavor. The objective of this study was to evaluate the effect of annatto color and starter culture on the flavor and functionality of whey protein concentrate (WPC). Cheddar cheese whey with and without annatto (15mL of annatto/454kg of milk, annatto with 3% wt/vol norbixin content) was manufactured using a mesophilic lactic starter culture or by addition of lactic acid and rennet (rennet set). Pasteurized fat-separated whey was then ultrafiltered and spray dried into WPC. The experiment was replicated 4 times. Flavor of liquid wheys and WPC were evaluated by sensory and instrumental volatile analyses. In addition to flavor evaluations on WPC, color analysis (Hunter Lab and norbixin extraction) and functionality tests (solubility and heat stability) also were performed. Both main effects (annatto, starter) and interactions were investigated. No differences in sensory properties or functionality were observed among WPC. Lipid oxidation compounds were higher in WPC manufactured from whey with starter culture compared with WPC from rennet-set whey. The WPC with annatto had higher concentrations of p-xylene, diacetyl, pentanal, and decanal compared with WPC without annatto. Interactions were observed between starter and annatto for hexanal, suggesting that annatto may have an antioxidant effect when present in whey made with starter culture. Results suggest that annatto has a no effect on whey protein flavor, but that the starter culture has a large influence on the oxidative stability of whey.

Hydroxyl Radical-Stressed Whey Protein Isolate: Chemical and Structural Properties

Many whey protein-containing foods are prepared in the presence of reactive oxygen species generated during processing. The objective of the present study was to determine chemical and structural changes, including carbonyls, sulfhydryls (SHs), dityrosine, surface hydrophobicity, turbidity, and cross-linking, in whey protein isolate (WPI) exposed to FeCl3/H2O2 hydroxyl radical-generating systems (HRGS) at room temperature (20 °C). Protein carbonyl content in WPI increased (P < 0.05) with increasing concentrations of H2O2 when incubated for up to 10 h; total SH groups decreased (P < 0.05) in a similar fashion. The HRGS-oxidized WPI also showed a higher dityrosine content, surface hydrophobicity, and turbidity (P < 0.05) than nonoxidized WPI. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed substantial losses of β-lactoglobulin, α-lactalbumin, and bovine serum albumin, and a concomitant formation of protein polymers in oxidized WPI. The protein-oxidation indexes were all significantly correlated (P < 0.01). These oxidation-induced changes demonstrate high susceptibility of WPI to oxidative stress at room temperature and may explain variations in functionality of whey proteins often observed in formulated foods.

Improving Functionality of Whey Protein Concentrates from Different Sources*

Improving Functionality of Whey Protein Concentrates from Different Sources*

Influence of whey peptides on the surface activity of κ‐casein and β‐lactoglobulin A

Whey protein hydrolysate (WPH) was fractionated by reverse‐phase chromatography to obtain fractions of varying surface‐hydrophobicities. A model oil–water interface (MI) was pre‐coated with the WPH or fractions thereof. Contact angle (θ) of sessile drops of κ‐casein (κ‐CN) or β‐lactoglobulin A (β‐LGA) were measured on the MI. Pre‐coating of MI with un‐fractionated WPH decreased θ, that is, increased surface activity, of both κ‐CN (35–8.3°) and β‐LGA (38–21.3°). Conversely, pre‐coating of MI with the fractions significantly increased θ of both proteins as a function of hydrophobicity. Data provide insight into variability of whey protein functionality in food applications.

Enhanced Functionalities of Whey Proteins Treated with Supercritical Carbon Dioxide

The functionality of whey proteins can be modified by many approaches; for example, via complexation with carbohydrates, enzymatic cross-linking, or hydrolysis, and the objective of this work was to research the effects of supercritical carbon dioxide (scCO2) treatments on the functionalities of commercial whey protein products including whey protein isolates (WPI) and whey protein concentrates (WPC). The WPI and WPC powders and a 10% (wt/vol) WPI solution were treated with scCO2. The WPI solution was treated at 40°C and 10MPa for 1h, whereas WPI and WPC powders were treated with scCO2 at 65°C and 10 or 30MPa for 1h. Dynamic rheological tests were used to characterize gelation properties before and after processing. Compared with the unprocessed samples and samples processed with N2 under similar conditions, scCO2-treated WPI, whether dispersed in water or in the powder form during treatments, formed a gel with increased strength. The improvement in gelling properties was more significant for the scCO2-treated WPC. In addition, the scCO2-processed WPI and WPC powders appeared to be fine and free-flowing, in contrast to the clumps in the unprocessed samples. Proximate compositional and surface hydrophobicity analyses indicated that both compositional and structural changes may have contributed to enhanced whey protein functionalities. The results suggest that functionalities of whey proteins can be improved by scCO2 treatment to produce novel ingredients.