Whey Protein Solutions Research Articles

Probing the effect of protein corona on SERS signals: insights from melamine detection in milk matrix

Matrix effects limit the application of surface-enhanced Raman scattering (SERS) technology in the field of food safety. This study elucidated it from the perspective of protein corona by employing a model system for melamine SERS detection in milk. Compared with the melamine standard solution, higher detection limits (1 mg/L and 10 mg/L) are observed in milk matrix. The melamine signal exhibits an 80% reduction in whey protein solution, suggesting that protein has a significant impact on SERS signals. The changes in particle size, zeta potential and UV–vis spectra indicate the AuNPs interact with whey protein. Forming protein corona inhibits the melamine-induced AuNPs aggregation, reducing the number of ‘hot spot’ and the adsorption of melamine on AuNPs (from 0.28 mg/L to 0.07 mg/L), which may be responsible for signal loss. The found matrix effect from protein corona provides new insights for developing strategies about reducing matrix effect in SERS application.

Effects of Laccase and Transglutaminase on the Physicochemical and Functional Properties of Hybrid Lupin and Whey Protein Powder.

Plant-based protein is considered a sustainable protein source and has increased in demand recently. However, products containing plant-based proteins require further modification to achieve the desired functionalities akin to those present in animal protein products. This study aimed to investigate the effects of enzymes as cross-linking reagents on the physicochemical and functional properties of hybrid plant- and animal-based proteins in which lupin and whey proteins were chosen as representatives, respectively. They were hybridised through enzymatic cross-linking using two laccases (laccase R, derived from Rhus vernicifera and laccase T, derived from Trametes versicolor) and transglutaminase (TG). The cross-linking experiments were conducted by mixing aqueous solutions of lupin flour and whey protein concentrate powder in a ratio of 1:1 of protein content under the conditions of pH 7, 40 °C for 20 h and in the presence of laccase T, laccase R, or TG. The cross-linked mixtures were freeze-dried, and the powders obtained were assessed for their cross-linking pattern, colour, charge distribution (ζ-potential), particle size, thermal stability, morphology, solubility, foaming and emulsifying properties, and total amino acid content. The findings showed that cross-linking with laccase R significantly improved the protein solubility, emulsion stability and foaming ability of the mixture, whereas these functionalities were lower in the TG-treated mixture due to extensive cross-linking. Furthermore, the mixture treated with laccase T turned brownish in colour and showed a decrease in total amino acid content which could be due to the enzyme's oxidative cross-linking mechanism. Also, the occurrence of cross-linking in the lupin and whey mixture was indicated by changes in other investigated parameters such as particle size, ζ-potential, etc., as compared to the control samples. The obtained results suggested that enzymatic cross-linking, depending on the type of enzyme used, could impact the physicochemical and functional properties of hybrid plant- and animal-based proteins, potentially influencing their applications in food.

Exploring the formation of surficial whey protein deposits under shear stress by rheofluidic approach

Understanding how shear affects whey protein stability is crucial to deal with typical industrial issues occurring at the bulk solution/surface interface, such as fouling during heat treatments. However, at the state of the art, this effect remains unclear, contrary to that of temperature. This article presents a novel strategy to study the impact of shear rate and concentration on the accumulation of whey protein surficial deposits. It consists in applying a range of shear rates (0–200 s−1) at controlled temperature (65 °C) on whey protein solutions (5–10 wt%) by a parallel plate rheometer equipped with a glass disc, thus allowing the off-line characterization of the deposits by microscopy. Our results highlight an unequivocal effect of increasing shear stress. At 5 wt%, it fosters the formation of primary deposits (≈ 10 μm), whereas at 10 wt% it results in the development of complex branched structures (≈ 50 μm) especially for shear rates ranging from 140 s−1 to 200 s−1. Based on the classification by size of the observed populations, we discuss possible hypotheses for the deposit growth kinetics, involving the interplay of different physico-chemical protein-surface interactions and paving the way to future further investigations.

Effects of soy protein on alleviating iron deficiency anemia in suckling rats with different iron supplements

Iron deficiency anemia (IDA) is common in infants and the fortification of infant formula with iron is an effective preventive strategy. Because of the severity of cow's milk allergy and the popularity of vegetarianism, soy-based infant formula has been widely used. However, whether soy-based infant formula is detrimental to iron absorption and increases the risk of IDA in infants requires further investigation. In this study, FeSO4 and its potential alternative encapsulated ferric pyrophosphate (FePP) were dissolved in soy protein and whey protein solution, and administered to IDA suckling rats by gavage to investigate the effects of protein system on the IDA remission by iron. Results showed that both types of iron supplement increased the body weight and improved the organ coefficients of IDA suckling rats irrespective of the protein system. In addition, for each type of iron supplement, both protein systems had the same recovery effects on hemoglobin, red blood cell count, hematocrit and body iron status. And, soy protein did not affect the expression of key iron absorption proteins or genes in the suckling rats. In conclusion, for IDA suckling rats, either FePP or FeSO4 in soy protein system has the same beneficial effect as whey protein system, and can effectively improve IDA. These findings provide a reference for the further application of soy-based infant formula and novel iron supplements.

Heat-stable whey protein isolate made using isoelectric precipitation and clarification

Residual lipids (RL) in whey protein isolate (WPI) are detrimental to optimal functional applications (e.g., foaming and low turbidity) and contribute to off-flavor development during powder storage. The objective of this research was to prepare an experimental WPI by removing RL without using the traditional microfiltration process and compare its properties with commercially available WPI made using microfiltration and some other whey powders. We hypothesize that by adjusting the pH of whey to <5.0, we would be close to the isoelectric point of any remaining denatured proteins (DP) and phospholipoproteins (PLP), and therefore reduce electrostatic repulsion between these molecules. Furthermore, demineralization of the acidified whey protein solution by UF combined with diafiltration (DF) should reduce ionic hindrance to aggregation and thereby help with the aggregation of these DP as well as most RL; centrifugation or clarification could be used to remove these materials. Calcium should also be more extensively removed by this approach, which should improve the heat stability of the experimental WPI. Demineralization was achieved on a pilot scale by acidifying liquid (cheese) whey protein concentrate containing 34% protein (WPC-34) to pH 4.5 using HCl, and UF of the whey protein solution along with extensive DF using acidified (pH ∼3.5) reverse osmosis filtered water. Demineralized whey protein solution was adjusted to various combinations of pH (4.1-4.9), conductivities (500-2,000 μS/cm), and protein concentrations (1%-7%) and then centrifuged at 10,000 × g for 10 min. The effective sedimentation (precipitation) of RL in these treatments was estimated by measuring the turbidity of the supernatants. Maximum precipitation was observed at pH 4.5 to 4.7. Reducing conductivity via UF/DF increased the precipitation of RL due to reduced ionic hindrance to aggregation. Maximum sedimentation of RL was observed at protein concentrations ≤3% because of a higher density difference between the precipitate and serum phase. Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis confirmed the sedimentation of phospholipoproteins, caseins, and DP upon isoelectric precipitation at pH ∼4.5, while native whey proteins or undenatured whey proteins remained soluble in the supernatant, unaffected by the pretreatment. To scale up the process, 750 L of fluid WPC-34 was acidified and demineralized by UF (volume concentration factor = 1.35) and DF until the permeate solids reached 0.1% (when desired demineralization was achieved), clarified using a pilot-scale desludging clarifier to remove RL, neutralized, ultrafiltered to concentrate the protein, and then spray-dried to produce an experimental WPI (91% protein and 1.8% fat on a dry basis [db]). In another trial, demineralized UF concentrate was clarified by gravity sedimentation and the supernatant was neutralized, ultrafiltered, and spray-dried to produce a second experimental WPI (91% protein and <1% fat db). These experimental WPI powders were compared with several commercially available WPI powders to assess functional properties such as solubility, heat stability, foamability and foam strength, gelation, and sensory attributes over accelerated storage. Experimental WPI had excellent functional properties, had low turbidity, were highly heat stable, and only developed very slight-to-slight off-flavors upon accelerated storage, and their properties were comparable to the WPI manufactured commercially using microfiltration even after accelerated storage.

Effect of Molecules' Physicochemical Properties on Whey Protein/Alginate Hydrogel Rheology, Microstructure and Release Profile.

The encapsulation of molecules with different physicochemical properties (theophylline, blue dextran, salicylic acid and insulin) in whey protein (WP) and alginate (ALG) microparticles (MP) for oral administration was studied. MP based on WP/ALG were prepared by a cold gelation technique and coated with WP solution after reticulation. Molecules influenced polymer solution viscosity and elasticity, resulting in differences regarding encapsulation efficiency (from 23 to 100%), MP structure and swelling (>10%) and in terms of pH tested. Molecule release was due to diffusion and/or erosion of MP and was very dependent on the substance encapsulated. All the loaded MP were successfully coated, but variation in coating thickness (from 68 to 146 µm) and function of the molecules encapsulated resulted in differences in molecule release (5 to 80% in 1 h). Gel rheology modification, due to interactions between WP, ALG, calcium and other substances, was responsible for the highlighted differences. Measuring rheologic parameters before extrusion and reticulation appeared to be one of the most important aspects to study in order to successfully develop a vector with optimal biopharmaceutical properties. Our vector seems to be more appropriate for anionic high-molecular-weight substances, leading to high viscosity and elasticity and to MP enabling gastroresistance and controlled release of molecules at intestinal pH.

Assessment of the Efficiency of Technological Processes to Modify Whey Protein Antigenicity.

Whey is a by-product that represents a cheap source of protein with a high nutritional value, often used to improve food quality. When used as a raw material to produce hypoallergenic infant formulas (HIF), a processing step able to decrease the allergenic potential is required to guarantee their safe use for this purpose. In the present paper, thermal treatments, high hydrostatic pressure (HHP), and enzymatic hydrolysis (EH) were assessed to decrease the antigenicity of whey protein solutions (WPC). For monitoring purposes, a competitive ELISA method, able to detect the major and most allergenic whey protein β-lactoglobulin (BLG), was developed as a first step to evaluate the efficiency of the processes. Results showed that EH together with HHP was the most effective combination to reduce WPC antigenicity. The evaluation method proved useful to monitor the processes and to be employed in the quality control of the final product, to guarantee the efficiency, and in protein antigenicity reduction.

Formation of thermo-reversible gels from whey proteins after combined thermal and ethanol pretreatment

Τhis study investigates the ability of whey proteins, which were pre-treated with ethanol (0–70%) and subjected tothermal treatment (70 °C for 60 min), to form thermo-reversible gels after removing the alcohol through freeze-drying. The ethanol-free gels were monitored by means of rheology and confocal laser scanning microscopy. Moreover, the role of ethanol during heating of whey proteins was investigated by UV difference spectroscopy. The results showed a retention of the denatured character (30–35%) of whey proteins after removal of ethanol, regardless of whether heating was applied. Intermolecular disulfide connections increased in whey protein solutions pretreated with 30 and 50% w/w ethanol. The determination of free –SH groups demonstrated that their number was increased by heating in the presence of ethanol and after ethanol's removal. Dynamic rheological measurements showed that ethanol-free gels, previously heated with 50% w/w ethanol, formed thermo-reversible gels upon cooling to 5 °C and exhibited significantly higher storage modulus values (G’∼300 Pa) than the counterparts without pretreatment of the proteins with ethanol (G’ = 0.0002 Pa). Generally, the partial retention of the denaturing effect of ethanol on whey proteins after its removal and their ability to form thermo-reversible gels could lead to new applications in the food and pharmaceutical industries.

Changes in the physiochemical, flavor and stability of whey protein solutions during UHT processing and storage: a review

A growing product on the worldwide dairy market is ultra-high temperature (UHT) milk, which can be kept at room temperature for 6 to 9 months. As the milk undergoes either direct or indirect UHT treatment at 140 ℃ for a few seconds, could kill the majority of bacteria and heat-resistance enzymes. The whey protein in milk will experience a series of physiochemical reactions such as denaturation, proteolysis, age gelation, sedimentation and Maillard after UHT treatment and following storage. The aims of this review were to screen occurred reactions in whey protein, allocate the generated flavor and analysis the volatile compounds. This review explained the mechanisms of the physiochemical reactions, and analysed the related flavor and relevant compounds of the flavor. Also, proposing several suggestions to improve UHT milk quality and find out suitable treatment conditions to prevent or minimize the effects of UHT on whey proteins.

Experimental and simulation-based investigation of the interplay between factor gradients following pulsed electric field treatments triggering whey protein aggregation

Novel pulsed electric field (PEF) applications to modify the techno-functionality of biomacromolecules have recently emerged. Insights into the involved interplay of factor domains (electrical, flow, concentration, temperature) with respect to the treatment chamber locations, and into the scalability are lacking. Therefore, a parallel plate batch (0.8 mL) and a scaled up parallel plate continuous (50 mL, 0.83 mL s −1 ) setup were built and simulated to investigate these domains and resulting gradient interactions using liquid whey protein solutions (0.5% w/w). In both setups, protein agglomerations and aggregations were observed below 60 °C at the electrode boundary layers for pulses in the range of 2–2.5 kV cm −1 , 10 μs, 40–350 Hz. The boundary layer is characterized by higher protein concentrations due to temperature- and pH-dependent migration trajectories, increased electrochemical reactivity (e.g., pH), and increased residence times due to the laminar flow or no flow conditions. Characterizing the domain interconnectivity led to effective scaling-up approaches of protein aggregations and insights into involved mechanisms. • Pulsed electric fields trigger whey protein migration and aggregations below 60 °C. • Identified regimes might provide a new process window to alter techno-functionalities. • Migration direction and aggregation location are pH-dependent. • Translation of observations from a batch to a scaled up continuous system. • Reactive boundary layer is characterized by overlaying factor domains and gradients.

Role of protein aggregate structure on the strength and underwater performance of barnacle-inspired adhesives.

Nature employs protein aggregates when strong materials are needed to adhere surfaces in extreme environments, allowing organisms to survive conditions ranging from harsh intertidal coasts to open oceans. Amyloids and amyloid-like materials are prevalent and amongst the most densely bonded aggregate structures, though how they contribute to wet adhesion is not well understood. In this work, waterborne protein solutions of individual whey proteins are cured in place using varied temperature to produce model adhesives enriched in amyloid or non-amyloid aggregates. Dry adhesive strengths range from 0.2-1.5 MPa, while wet adhesive strengths range from 0-0.5 MPa across the tested proteins and processing conditions, highlighting that both proper protein selection and controlled aggregation extent are necessary for successful underwater performance. For bovine serum albumin, the amyloid-enriched adhesive was able to retain ca. 500 kPa bond strength underwater throughout extended immersion and thermal degradation testing, while the non-amyloid adhesive weakened by up to 80%. As freestanding gels, higher temperature processing improved underwater stability for all the protein materials, with amyloid-rich structures remaining mostly water-insoluble after 30 days submerged in water. Protein-based adhesives with a controlled aggregate structure shed light on the ability of amyloid-containing materials to remain adhered underwater, a necessary trait for the survival of many organisms.

Effect of calcium on the reversible and irreversible thermal denaturation pathway of β-lactoglobulin

Thermal denaturation of β-lactoglobulin (BLG), boosted in the presence of calcium ions, is responsible for the dairy fouling issue in milk processing. However, the reported kinetic model concerning BLG denaturation was generally based on a simplified one-step reaction model where the unfolding of the protein was considered as a kinetically driven reaction. In such a model, the presence of break-slope phenomenon in the Arrhenius plot was justified by the fact that unfolding step constitutes a rate-limited step compared to aggregation at low temperatures. Nevertheless, there is accumulated experimental evidence implying that the unfolding step is much faster than aggregation regardless of the temperature. Therefore, in this paper, it is proposed that the thermal unfolding of BLG is thermodynamically controlled such that a chemical equilibrium between native and unfolded BLG species can be instantaneously established, followed by an irreversible aggregation of unfolded BLG. This novel approach allows to mathematically interprets the break-slope behavior in the Arrhenius plot. The developed model was applied to investigate the effect of Ca 2+ on the unfolding equilibrium and subsequent aggregation process of BLG in whey protein solutions. Ca 2+ was confirmed to have a protective role on the unfolding equilibrium of BLG by increasing the enthalpy Δ H u and decreasing the equilibrium constant K c , while it facilitated the aggregation of BLG by showing a reduction of the corresponding enthalpy and entropy which cannot be seen as reported using one-step reaction model. This approach allows us to be closer to reality when mimicking the heat-induced appearance/disappearance of different BLG species, including native, unfolded and aggregated ones. Accurate population balance of these foulant species during thermal processing could lead to new perspectives on fouling prediction. • Thermal unfolding of β-lactoglobulin can be considered to occur instantaneously. • Unfolding of β-lactoglobulin is thermodynamically driven. • New model mathematically interprets the break-slope phenomenon in Arrhenius plot. • Ionic calcium has a protective role on the unfolding of β-lactoglobulin. • Calcium favors β-lactoglobulin aggregation by showing decreased enthalpy.

Investigation of the film-forming ability of proteins subjected to UV treatment for the dairy industry development

Film-forming mixtures based on reconstituted solutions of whey protein concentrates (WPC) with a protein content of 2.0 and 5.0% were subjected to UV irradiation in the range from 90 to 150 J/ml. With an increase in the dose of UV irradiation in film-forming solutions, the solubility of the protein decreased, the greatest effect was achieved in a mixture with a protein content of 2.0%. The decrease in solubility indirectly proved the process of aggregation of protein molecules in the studied solutions. It has been shown that UV exposure improves the strength properties of protein films. The highest specific stress at film rupture at an irradiation dose of 150 J/ml was 23.11 MPa in a 5.0% protein solution and 5.74 MPa in a 2.0% solution. The indicator of the applied force increased more intensively when processing a 5.0% protein solution, and amounted to 16.00 N in the case of a 2.0% solution, and 24.82 N in a 5.0% solution.

Effects of Heat Treatment Duration on the Electrical Properties, Texture and Color of Polymerized Whey Protein.

In this research effects of heat treatment duration on the electrical properties (zeta potential and conductivity), texture and color of polymerized whey protein (PWP) were analyzed. Whey protein solutions were heated for 30 min to obtain single-heated polymerized whey protein (SPWP). After cooling to room temperature, the process was repeated to obtain double-heated polymerized whey protein (DPWP). The largest agglomeration was demonstrated after 10 min of single-heating (zeta potential recorded as −13.3 mV). Single-heating decreased conductivity by 68% and the next heating cycle by 54%. As the heating time increased, there was a significant increase in the firmness of the heated solutions. Zeta potential of the polymerized whey protein correlated with firmness, consistency, and index of viscosity, the latter of which was higher when the zeta potential (r = 0.544) and particle size (r = 0.567) increased. However, there was no correlation between zeta potential and color. This research has implications for future use of PWP in the dairy industry to improve the syneretic, textural, and sensory properties of dairy products.

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

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

Effects of pH, stirring rate, reaction time and sequential ultrafiltration of whey protein solution on recovery and purification of glycomacropeptides.

This study was designed to show the changes in glycolmacropeptides (GMPs) of whey protein solution (WPS) due to different pretreatments before and after ultrafiltration (UF). The combined form of two variants (A&B) of GMPs is a helpful compound for nutritional management of phenylketonuria and ulcerative-colitis diseases and has low content of phenylalanine (Phe). WPS with 10% concentration was prepared, acidified (adjusted to pH = 3.0), and passed through a PES (polyethersulfone) membrane in the 1st-stage of ultrafiltration (UF-1). Then the resulting permeate was neutralized and went through the 2nd-stage of ultrafiltration (UF-2) under similar conditions. Four experiments of TRT-CON, CON-TRT, TRT-TRT, and CON-CON were used with different pretreatments, where TRT was a mixing-treatment of 30 min at 150 RPM applied either after acidification of WPS or after neutralization of first permeate and before UF-2 process. While the concentration and purity of the combined GMPs in UF-2 retentate in TRT-TRT respectively were >95.6 and 99.5%, its Phe became <10 ppm among the experiments. Highly glycolyzed polymers of GMPs (MW = 45-50 kDa) were formed in the TRT-TRT experiment and went through the pore sizes of PES membrane of UF-1 easily because of their flexible structure. However, they remained in the UF-2 retentate, due to to the formation of bulky polymers. The TRT-TRT experiment had the highest reversible and irreversible resistances for passing through the UF-1 and remaining on the UF-2 membranes, and its fouling index was significantly less than other experiments.

Cysteine residues are responsible for the sulfurous off-flavor formed in heated whey protein solutions

Odor-active volatile sulfur compounds are formed in heated food protein systems. In the present study, hydrogen sulfide (H2S) was found to be the most abundant sulfur volatile in whey protein solutions (whey protein isolate [WPI], a whey model system and single whey proteins) by gas chromatography-flame photometric detector (GC-FPD) analysis after heat treatments (60–90 °C for 10 min, 90 °C for 120 min and UHT-like treatment). H2S was detected in WPI after heating at 90 °C for 10 min, and was significantly increased at higher heat load (90 °C for 120 min and the UHT-like treatment). Site-specific LC-MS/MS-based proteomic analysis was conducted, monitoring desulfurization reactions in these protein systems to investigate the mechanism of H2S formation in heated WPI. Cysteine residues from beta-lactoglobulin were found to be responsible for the formation of H2S in heated WPI, presumably via beta-elimination.

Production of whey protein nanofiber as a carrier for copper entrapment

Novel electrospun fibers from aqueous whey protein solution with and without a carrier polymer have been developed and characterized, exploring the ability of those fibers to carry nutrients that are considered attractive. In this study, whey protein concentrate (WPC) solution electrospun into nanofibers in conjunction with (1% w/w in solution) and without a spinnable polymer, polyethylene oxide (PEO), for carrying copper. The electrospun fibers were successfully produced from WPC/copper and a PEO/WPC/copper polymer solution under the applied voltage of 15–23 kV, when the copper concentration was relatively low. The applied voltage has no significant effect on the size of the fibers produced by WPC/copper and PEO/WPC/copper polymer systems (p > 0.05). The copper concentration in WPC/copper and the PEO/WPC/copper polymer solution significantly affect the viscosity of the solution and the size of the fiber (p < 0.05), but it has no observable change on the morphology of the fiber. The addition of PEO in the polymer solution slightly increases the solution viscosity, but the fiber of the polymer solution with PEO was 100–400times smaller than that without PEO. Micron fibers prepared by WPC polymer solution and nanofibers prepared by PEO/WPC polymer solution successfully carried copper.

Whey protein fouling prediction in plate heat exchanger by combining dynamic modelling, dimensional analysis, and symbolic regression

Heat treatment of whey protein solution is a common industrial practice to texturise dairy derived products and meet shelf-life requirements. Thermal treatment is frequently interrupted for cleaning which consumes a large amount of water at different pH to remove deposits from the heating surface. Although it has been a research topic for decades, fouling growth models are still poorly predicted beyond the model training dataset. Here, parameters in a dynamic 2D plate heat exchanger (PHE) model were fitted to capture deposit mass when three variables are manipulated. These are whey protein concentration (0.25–2.5% w/w), calcium concentration (100 and 120 ppm) in the feed and PHE configuration, represented by the number of heating channels (5 and 10 channels). The PHE model consists of thermal, reaction, and fouling sub-models to account for the key events behind deposit formation. The PHE fouling model has a single parameter that needs re-estimation if the processed whey protein solution and process conditions are slightly changed. In the past, this case specific re-estimation has hindered the prediction capability of the model. In this regard, dimensional analysis of the PHE and symbolic regression were used to create a mathematical relationship for the fouling model adjustable parameter, enabling estimation of deposit mass for a wider range of whey derivatives and process conditions. The modelling approach was validated for three different scenarios representing different thermal profiles and whey powder. The proposed methodology increases the ability to predict fouling for different operating conditions and whey protein solutions.

Tuning the physical and functional properties of whey protein edible films: Effect of pH and inclusion of antioxidants from spent coffee grounds

This study presents a food waste valorization scheme targeting to the production of novel whey protein edible films. Initially, the effect of pH of whey protein on the physical properties of films was studied. Whey protein edible films were subsequently supplemented by an antioxidant-rich extract derived from spent coffee grounds targeting to improve the functional properties of films. The results showed significant changes at different pH, indicating that, depending on the intended application, films' properties can be controlled by shifting pH of whey protein solution. Inclusion of antioxidants resulted in edible films with UV-light resistance properties, whereas the mechanical properties and in particular tensile strength and elastic (Young's) modulus were increased. Water vapor permeability of films was considerably increased by the inclusion of antioxidants, compared to control films. Additionally, whey films enriched with phenolic compounds from spent coffee grounds presented high antioxidant activity (73.2%), which was decreased only 16.8% after a 12-month storage period. The proposed valorization scheme resulted in the development of edible films with tailor-made properties conforming with the pillars of Circular Economy.