Presence Of Whey Proteins Research Articles

تحضير اغشية صالحة للأكل باستخدام بعض السكريات المتعددة وبروتينات الشرش ودراسة بعض خواصها

This study aimed to prepare edible films based on polysaccharides and whey proteins. Seven formulations were prepared from dextran, xanthan, and carrageenan with whey proteins, glycerol, and black seed oil. The mechanical and barrier properties were studied for edible films like thickness, tensile strength, elongation, and water vapor permeability. The use of equal concentrations of polysaccharides (2gr) with the presence of whey proteins (1gr) and glycerol as plasticizers gave the best elongation at the break of the film (178%) and water vapor permeability the highest value(5.7g.mm/m2.h.kPa). Film Thickness was 56µm and Tensile 28MPa.This edible film was the best among the other formulation used in molasses medium.

Corrigendum to “Cooling crystallization of lactose in the presence of whey protein and lactic acid impurities” [J. Food Eng. 311 (2021)110729

Corrigendum to “Cooling crystallization of lactose in the presence of whey protein and lactic acid impurities” [J. Food Eng. 311 (2021)110729

Corrosion and metal release characterization of stainless steel 316L weld zones in whey protein solution

Stainless steel ASTM 316 L is often used in the food industry as contact material with protein-rich dairy products. It has to be welded at some locations for many of these contact materials. This study aimed at i) determining any combined effects of the presence of whey protein (WP) and welding-induced weaknesses on corrosion and metal release, and ii) determining the appropriate welding procedure and filler metal (316 L, 309 L, 312). All weld metals (WMs) showed a higher pitting corrosion susceptibility as compared to the base metal (BM). Under induced friction (stirring), WP significantly enhanced the metal release from all materials, which was accelerated between 1 and 3 days of exposure. Post-imaging indicated pits. 312-WM released significantly higher amounts of metals as compared to the BM and the other WMs. This study indicated that the presence of WP, friction, and weldment-induced corrosion susceptibilities could synergistically cause metal release and corrosion of food contact materials.

Crystallization of Lactose-Protein Solutions in the Presence of Flavonoids.

Lactose is commonly crystallized in the presence of whey proteins, forming co-crystals of lactose and proteins. This work hypothesized that flavonoids such as rutin or epigallocatechin-3-gallate (EGCG) could be incorporated into the lactose and protein co-crystal structure since flavonoids may interact with both lactose and proteins. The interactions between whey proteins and flavonoids were first studied. Then, lactose-protein solutions were crystallized with and without flavonoids, measuring the kinetic parameters of crystallization and characterizing the resulting crystals. The incorporation of flavonoids in lactose-protein co-crystals depended on the hydrophilic nature of flavonoids. The hydrophilic EGCG was scarcely enclosed in the crystal lattice of lactose and avoided the inclusion of whey proteins in the crystals. In contrast, the less water-soluble rutin interacted with whey proteins and lactose, leading to the formation of co-crystals containing lactose, protein, and a large concentration of rutin (3.468 ± 0.392 mg per 100 mg of crystals).

Cooling crystallization of lactose in the presence of whey protein and lactic acid impurities

Whey protein and lactic acid are two main impurities affecting the crystallization recovery of lactose from acid whey solutions. This study systematically examined the individual and combined effect of whey protein and lactic acid on the purity of the recovered lactose. From batch cooling stirred tank crystallization experiments, whey protein affected the purity by co-precipitation from the denaturation of protein. In contrast, lactic acid affected the purity by incorporation into the lactose crystal structure. This was primarily due to the similarity in the molecular structure between lactic acid and lactose. The presence of both impurities led to an undesired synergistic effect, which led to a significant increase in the impurity level. The low acidity and enhanced aggregation of protein were the main cause of this undesired synergistic effect. This study highlights the importance of the effective separation of whey protein in acidic whey solutions prior to the recovery of lactose by crystallization. • Denaturation of protein at high temperature was co-precipitated with lactose. • Denatured protein at pH of 4.5 resulted in a larger particle size distribution due to aggregation. • The combination of protein and lactic acid yielded the lowest purity.

Dye-protein interactions between Rhodamine B and whey proteins that affect the photoproperties of the dye

In fluorescence labeling, proteins are usually assayed to minimize the impact of fluorophores on their intrinsic structure and functions, however, the effect of the protein itself on the fluorescence properties of its attached fluorophore has not been studied at length. In this paper, the fluorescence properties of the ubiquitously used Rhodamine B (RhB) were investigated in the presence of whey proteins, particularly at alkaline conditions. Results reveal the existence of dye-protein interactions whether the dye is free or covalently linked to proteins. Alkali was able to destroy these interactions, while base-denaturation of proteins also occurred that complicates the dye-protein interactions. In addition, RhB was found able to quench the tryptophan (Trp) fluorescence of whey proteins, leading to the formation of nonfluorescent Trp-RhB complex. This stable Trp-RhB complex might explain the irreversible binding of RhB upon thermal-induced whey protein aggregates. This finding could suggest a cheaper alternative of labeling on proteins.

Characterization of protein-enriched yogurt and its effects on the lean body weight gain and electrical activity in skeletal muscle of physically active individuals

Protein-enriched yogurts have experienced a growth in marketability in recent years, being demanded especially by consumers interested in increasing their daily apportion of proteins. In this study, the objective was to develop a protein-enriched yogurt and to compare it with a non-enriched yogurt in terms of their physicochemical characteristics, texture, and sensory acceptance after different storage periods and their effects on the lean body weight gain and electrical activity in skeletal muscle of physically active individuals. The supplemented whey protein had a buffering effect on the product, leading to its lower syneresis. Both formulations had similar hardness, indicating that the textural parameters had been retained in the protein-enriched yogurt. Panelists indicated no differences in sensorial attributes between the non-enriched and protein-enriched yogurts, with the sensory characteristics of each product being mainly described by the presence of whey protein and the curdled texture. Consumption of the protein-enriched yogurt did not influence the lean body weight gain by physically active individuals.

Microstructure of kajmak skin layer made during kajmak production

Kajmak is a unique dairy product with a long tradition in Balkan countries and the Middle East. Kajmak skin layers are formed during 60 minutes of kajmak production, influencing the quality and determining the structure of the final product. The influence of milk composition and heat treatments (75-95 °C/5min) on the composition, microstructure and protein distribution of kajmak skin layers was investigated in this study. Microstructure was determined using scanning electron microscopy (SEM), while the distribution of protein fractions was studied by SDS PAGE in reducing and non-reducing conditions. Kajmak skin layers obtained from milk treated at common intense heat regime were characterized with β-LG and α-LA mainly as disulfide-linked complexes, while lower temperature (75 °C) caused the presence of whey proteins in dominantly individual form. More severe treatments (85 °C, 90 °C and 95 °C) caused the full involvement of β-LG in the complexes, since a certain amount of α-LA was found as a monomer. The kajmak skin layer composition, severity of the applied milk heat treatment and the linked whey proteins exhibited a very strong influence on kajmak skin layer microstructure. The microstructure of kajmak skin layer with a low fat content and fat/protein (F/P) ratio was characterized by a compact structure with a dense protein matrix. High fat content and F/P ratio resulted in a dispersive form of the stretched protein network. Kajmak skin layers produced from milk with added whey proteins were characterized by fibrous, thread-like segments, due to the incorporated denatured whey proteins, especially linked β-LG.

Effects of polymerized whey protein on survivability of Lactobacillus acidophilus LA-5 during freeze-drying.

Probiotic cultures are commonly freeze‐dried for storage and distribution. However, freeze‐drying and subsequent storage are accompanied by a decline in cell viability. Whey protein (WP) or polymerized whey protein (PWP) was used to protect Lactobacillus acidophilus LA‐5 against damage during freeze‐drying process and the subsequent storage. The protection capacity and effects of polymerized whey protein protected freeze‐dried L. acidophilus LA‐5 on physiochemical properties of cow and goat milk yoghurts were evaluated in comparison with maltodextrin (MD). The survival rate of L. acidophilus LA‐5 after freeze‐drying decreased in the order of MD (80.91%) > PWP (69.86%) > WP (64.89%). The particles of WP‐ and PWP‐based freeze‐dried samples showed an average diameter of about 10 μm, which was significantly higher than that of MD‐based particles (1.5 μm). Both whey protein preparations showed higher protecting effect than MD at high humidity condition during the 180‐day storage. Addition of freeze‐dried L. acidophilus LA‐5 with the presence of WP or PWP improved the protein content and decreased spontaneous whey separation and syneresis significantly for both yoghurts. PWP‐protected L. acidophilus LA‐5 addition significantly improved the firmness and adhesiveness of the yoghurt. Freeze‐dried L. acidophilus LA‐5 mixed with PWP had higher survivability in yoghurts compared with the culture alone at the end of storage. Data indicated that whey protein can be used to protect probiotics during freeze‐drying and may also improve the physiochemical properties of the yoghurt.

Effects of Cholesterol Extraction Process and Fat and Whey Protein Additions on Ice Cream Mixes.

The aim of this work was to evaluate the cholesterol extraction process in ice cream mixes (ICMs) by using β-cyclodextrin (βCD) and to analyze the effect of this extraction on the ICM rheological, stability, and sensory characteristics. The effects of fat and whey protein (WP) additions on ICM stability were also evaluated. The maximum percentage obtained for cholesterol extraction was 93.6%. The flow curves indicated that ICM showed a thixotropic behavior before and after cholesterol extraction, which was enhanced when the fat content and/or percentage of βCD increased. The stability of ICM with cholesterol-reduced content (RCho-ICM) was influenced by the fat content and/or the presence of WP. The RCho-ICM with the highest fat and/or WP addition showed less tendency to melt and had the smallest amount of accumulated molten liquid. These latter ICMs presented the slowest melting rates. Also, RCho-ICMs proved to be more stable than ICMs. RCho-ICM samples obtained with a ratio of βCD/fat content of 1% w/w were evaluated by a trained sensory panel. In addition, an acceptability test of the sample with better sensory attributes was conducted. PRACTICAL APPLICATION: The effects of a cholesterol extraction process and fat and whey protein additions on the rheological and stability characteristics of ice cream mixes were evaluated. The extraction of cholesterol from an ice cream mix is interesting from a nutritional point of view and the extraction process of cholesterol itself may also help to improve the mix stability by controlling the fat and/or whey protein contents. These findings may prove useful as a starting point for the rational design of new functional ice cream mixes.

Stability of vitamin B12 with the protection of whey proteins and their effects on the gut microbiome.

Cobalamin degrades in the presence of light and heat, which causes spectral changes and loss of coenzyme activity. In the presence of beta-lactoglobulin or alpha-lactalbumin, the thermal- and photostabilities of adenosylcobalamin (ADCBL) and cyanocobalamin (CNCBL) are increased by 10-30%. Similarly, the stabilities of ADCBL and CNCBL are increased in the presence of whey proteins by 19.7% and 2.2%, respectively, when tested in gastric juice for 2 h. Due to the limited absorption of cobalamin during digestion, excess cobalamin can enter the colon and modulate the gut microbiome. In a colonic model in vitro, supplementation with cobalamin and whey enhanced the proportions of Firmicutes and Bacteroidetes spp. and reduced those of Proteobacteria spp., which includes pathogens such as Escherichia and Shigella spp., and Pseudomonas spp. Thus, while complex formation could improve the stability and bioavailability of cobalamin, these complexes might also mediate gut microecology to influence human nutrition and health.

Individual and combined effect of pH and whey proteins on lactose crystallization

Lactose is recovered by crystallization from cheese whey that is a by-product of cheesemaking. The whey used for the recovery of lactose usually has a residual content of protein that alters the crystallization of lactose. In addition, the pH of whey may fluctuate depending on the cheese variety. However, there is little information on how the pH modifies the effect that whey proteins have on lactose crystallization. Accordingly, this work aimed to evaluate the individual and combined effect of whey proteins and pH on the kinetics of crystallization, the crystal size distribution and the crystallinity of lactose. The addition of whey proteins in lactose solutions (25% v/v) modified the process of lactose crystallization. However, the effect that whey proteins had on lactose crystallization heavily depended on the pH. The number of crystals per milliliter as well as the growth and size distribution of crystals was the most affected with the changes in pH (pHs of 7, 5.5 and 4) and the addition of whey proteins (0 and 0.63%). All the treatment produced mostly α-lactose monohydrated but some treatments also generated crystals of β-lactose (pH 5.5, 0% of proteins). Amorphous lactose was observed mainly in lactose solutions adjusted at pH 7 and added with whey proteins. This particular treatment also incorporated the highest amount of protein into the lattice of lactose crystals. The results of this work highlight the importance of controlling the pH of lactose crystallization, especially if there is a presence of whey proteins.

Heat-induced gelation of aqueous micellar casein suspensions as affected by globular protein addition

The aim of this work was to investigate how the heat-induced gelation of micellar casein (MC) suspensions (6% w/w MC) is affected by the addition of three globular proteins (GP) (whey proteins (WP), pea proteins (PP) and soy proteins (SP); from 0 to 6% w/w) at pH ≤ 6.0. Storage moduli (G′) were measured as a function of temperature from 20 °C to 90 °C. Heat-induced gelation was characterised by a sharp increase in G′ at a critical temperature (Tc). The suspensions were then held at 90 °C for 1h to determine the stiffness of the gels. Regardless of the pH, Tc of MC suspensions increased with the addition of GP. Interestingly, this increase depended on the type of GP and was stronger in the order SP > PP > WP. This effect was mainly explained by differences in calcium binding efficiency between the different GP (SP > PP >> WP) and/or the mineral composition of the ingredients. Native GP influence gelation of MC by binding calcium, thus reducing the amount available for MC to bridge, leading to an increase in Tc. Tc of the suspensions decreased with decreasing pH due to both decrease in the net charge density of MC and release of Ca2+ that in turn favoured heat-induced gelation of MC. Gel stiffness was not influenced much by PP or SP addition. However, it increased significantly in the presence of WP, due to co-aggregation of denatured WP with MC above 70 °C, which reinforced the MC network.

Effect of milk protein composition of a model infant formula on the physicochemical properties of in vivo gastric digestates

We investigated the effect of protein composition and, in particular, the presence of whey proteins or β-casein on the digestion behavior of a model infant formula using an in vivo piglet model. Three isocaloric diets optimized for piglets were prepared with the same concentrations of protein. For protein source, 1 diet contained only whey proteins and 2 contained a casein:whey protein ratio of 40:60 but differed in the amount of β-casein. To obtain the desired protein compositions, skim milk was microfiltered at 7 or 22°C, and retentates and permeates were combined with whey protein isolate. The diets were optimized to the nutritional needs of the piglets and fed to 24 newborn piglets for 18 d. Eight piglets were also fed ad libitum with sow milk and considered only as reference (not included in the statistical analysis). The study was carried out in 2 blocks, killing the animals 60 and 120 min after the last meal. All gastric contents, regardless of diet, showed a wide range of pH. Postprandial time did not affect the pH or physical properties of the gastric digesta. The digesta from whey protein-casein formulas showed significantly higher viscosity, a higher storage modulus, and a denser microstructure than digesta obtained from piglets fed whey protein formula. The β-casein:total casein ratio at the level used in this study did not significantly affect the physical and chemical properties of the stomach digestate. Although caseins showed extensive gastric hydrolysis, whey proteins remained largely intact at both postprandial times. The results indicate that the presence of different concentrations of milk proteins can be critical to the digestion properties of the food matrix and may affect the nutritional properties of the components.

Ultrasound-assisted crystallization of lactose in the presence of whey proteins and κ-carrageenan

The conventional process of lactose crystallization is prolonged, hardly controllable and the crystals have low quality. In this work, the effect of ultrasound on the crystallization of lactose in an aqueous system was assessed. Additionally, it was studied how the presence of whey proteins (which are a common impurity) and κ-carrageenan (that possess high water-binding capacity) could modify the process of lactose crystallization. Lactose solutions at 25% were sonicated in a continuous flow chamber at two different energy densities (9 and 50 J mL−1) before the start of crystallization. Some of these lactose solutions were previously added with κ-carrageenan (0, 150 and 300 mg L−1), with whey proteins (0.64%) or with both at the same time. Ultrasound sped up the rate of crystallization, decreased the crystal’s size and narrowed the crystal size distribution (CSD). The presence of whey proteins accelerated the process of crystallization but induced the formation of amorphous lactose. Likewise, the rate of lactose crystallization was improved by the addition of 150 mg L−1 of carrageenan. Whereas, the combination of carrageenan and whey proteins generated the smallest crystals (6 μm), the narrowest CSD and minimized the formation of amorphous lactose.

Role Of Metalloproteases In Shedding Of Dipeptidyl-peptidase Iv From Skeletal Muscle Cells

Dipeptidyl- Peptidase IV (DPP-IV) is a membrane bound myokine that is involved in converting the powerful vasoconstrictor, neuropeptide Y, into the non-vasoconstricting form. Previous work in this lab suggested that DPP-IV is released from myocyte cell cultures, when a whey protein solution is applied, but not when leucine is applied. A possible mechanism is a process called shedding that occurs via the metalloproteases MMP2 and MMP9. These MMP’s are known to mediate the shedding of DPP-IV from adipocytes and smooth muscle cells and exist in commercially available whey protein, but not in leucine products. PURPOSE: To determine if the shedding of DPP-IV from skeletal muscle cells is mediated by metalloproteases. We hypothesized that when MMP2 and MMP9 were inhibited (i), the amount DPP-IV released in the presence of whey protein would be decreased. METHODS: C2C12 cells underwent 4–5 days of differentiation. They were treated for 6 hours with one of the following: leucine (Leu) or whey protein (WP), LEU+MMP2i, Leu+MMP9i, Leu+complete protease inhibitor (CP), WP+MMP2i, WP+MMP9i, or WP+CP. Control plates were also run with one of the following: MMP2i, MMP9i, CP, or dimethyl sulfoxide (DMSO-vehicle for inhibitors). The media was collected for DPP-IV activity measurements, which were measured using a fluorometric assay. RESULTS: The DPP-IV activity of the control cells treated with only the inhibitors and vehicle, as well as Leu+MMP2i and Leu+MMP9i were not significantly different from Leu. Only Leu+CP had a significant decrease in DPP-IV activity from Leu (22.5% decrease; p=0.01). DPP-IV activity of the DMSO group was significantly increased from WP (35.4% increase; p<0.001); however when the inhibitors were added, this increase was no longer significant. When whey protein was given with the inhibitors, DPP-IV activity significantly decreased for all 3 groups from WP (WP+MMP2i: 32.3% decrease; WP+MMP9i: 40.6% decrease, and WP+CP: 51.0% decrease; all p<0.0001) CONCLUSION: The shedding of DPP-IV from skeletal muscle cells is mediated by metalloproteases 2 and 9, which are present in whey protein. This is a possible mechanism by which milk products may affect neuropeptide Y-mediated blood flow.

Effect of pH, transmembrane pressure and whey proteins on the properties of casein micelle deposit layers

Deposit layers arising during milk microfiltration have not yet been well described with regard to their structural build-up. Besides casein micelles forming the bulk of the deposit, whey proteins are integrated into the milk protein deposit. Both the deposited protein layer and the membrane are involved in the retention of both protein fractions. Therefore, this study focusses on the impact of whey proteins on casein micelle deposit compressibility and reversibility. Compressibility and specific fouling resistance of casein micelle deposits were reduced in the presence of whey proteins. In other words, the deposit layer becomes more open or more porous due to whey protein attachment to the casein micelle surface. Furthermore, diffusive removability of the deposit layers was affected by pH and whether or not whey proteins were present. Convective removal by fluid forces was found to be almost entirely independent of pH or the presence of whey proteins. This shows that deposit layers arising during milk microfiltration consist of three phases, a diffusively removable micro-porous deposit, a gel-like convectively removable layer and internal membrane fouling.

Influence of olive oil phenolic compounds on headspace aroma release by interaction with whey proteins.

The release of volatile compounds in an oil-in-water model system obtained from olive oil-whey protein (WP) pairing was investigated by considering the effect of phenolic compounds. Human saliva was used to simulate mouth conditions by retronasal aroma simulator (RAS) analysis. Twelve aroma compounds were quantified in the dynamic headspace by SPME-GC/MS. The results showed significant influences of saliva on the aroma release of virgin olive oil (VOO) volatiles also in the presence of WP. The interaction between WP and saliva leads to lower headspace release of ethyl esters and hexanal. Salivary components caused lower decrease of the release of acetates and alcohols. A lower release of volatile compounds was found in the RAS essay in comparison to that in orthonasal simulation of only refined olive oil (without addition of saliva or WP), with the exception of hexanal and 1-penten-3-one, where a significantly higher release was found. Our results suggest that the extent of retronasal odor (green, pungent) of these two volatile compounds is higher than orthonasal odor. An extra VOO was used to verify the release in model systems, indicating that WP affected aroma release more than model systems, while saliva seems to exert an opposite trend. A significant increase in aroma release was found when phenolic compounds were added to the system, probably due to the contrasting effects of binding of volatile compounds caused by WP, for the polyphenol-protein interaction phenomenon. Our study could be applied to the formulation of new functional foods to enhance flavor release and modulate the presence and concentrations of phenolics and whey proteins in food emulsions/dispersions.

Synthesis, cellular uptake, and biodistribution of whey-rich nanoparticles.

Whey-poly(acrylic acid) (whey-PAA) nanoparticles are prepared by polymerizing acrylic acid (AA) monomer in the presence of whey protein in a complete aqueous medium. The properties, drug loading, and release as well as in vitro cytotoxicity of whey-PAA nanoparticles are examined. The cellular uptakes and penetration of nanoparticle in the SH-SY5Y monolayer cells and multicellular tumor spheroids are observed. The in vivo distribution of the nanoparticles in tumor-bearing mice is evaluated. Confocal laser scanning microscopy and co-localization images show that the nanoparticles are well internalized by the cells through the endocytosis mechanism. Drug-loaded whey-PAA nanoparticles can penetrate multicellular tumor spheroids more deeply. In vivo near-infrared fluorescence imaging examination and in vivo DOX distribution show that the drug-loaded whey-PAA nanoparticles can well accumulated in the tumor site. Thus, these whey-rich nanoparticles seem to be very promising drug carriers for drug delivery.

Exopolysaccharide–milk protein interactions in a dairy model system simulating yoghurt conditions

Although exopolysaccharides (EPS) produced by lactic acid bacteria can be used to modulate the rheological and physical properties of fermented milk, the interactions between EPS and milk proteins in such complex system remain poorly understood. This work aimed to study the interaction between EPS with different structural characteristics and caseins in the absence or presence of whey proteins in a dairy model system simulating yoghurt conditions. The study was expected to highlight the contribution of whey proteins to the casein network and identify possible interactions of EPS with the casein network. Four starters were used: HC15/210R (control), HC15/291 (neutral, stiff, branched EPS), HC15/702074 (neutral, flexible, highly branched EPS), and 2104/210R (anionic, stiff, linear EPS). Fermentation was performed at 42 °C until the pH reached 4.6. Microstructure and rheological and physical properties (syneresis, elastic modulus, and apparent viscosity) were measured. The diversity of EPS functionalities depended on the specific structures of the EPS: stronger gels were formed with the anionic EPS from strain 2104 probably because of electrostatic interactions, although limitation of syneresis was more influenced by the neutrality and stiffness of the EPS backbone of strain 291. The sequential addition of casein and whey proteins to the dairy model system revealed their individual contribution to the microstructure of the protein network. This study showed that the rheological and physical properties of fermented milk can be modulated by the casein and whey protein concentrations and the use of different EPS with specific structural characteristics.