Whey Protein Solutions Research Articles

Niosome-loaded cold-set whey protein hydrogels

The α-tocopherol-carrying niosomes with mean diameter of 5.7μm were fabricated and charged into a transglutaminase-cross-linked whey protein solution that was subsequently gelled with glucono delta-lactone. Encapsulation efficiency of α-tocopherol within niosomes was ≈80% and encapsulation did not influence the radical scavenging activity of α-tocopherol. Fourier transform infrared (FTIR) spectroscopy suggested formation of ε-(γ-glutamyl) lysine cross-linkages by transglutaminase and that enzymatic cross-linking increased proteins hydrophobicity. FTIR also proposed hydrogen bonding between niosomes and proteins. Dynamic rheometry indicated that transglutaminase cross-linking and niosomes charging of the protein solution enhanced the gelation process. However, charging the cross-linked protein solution with niosomal suspension resulted in lower elastic modulus (G′) of the subsequently formed gel compared with both non-cross-linked niosome-loaded and cross-linked niosome-free counterparts. Electron microscopy indicated a discontinuous network for the niosome-loaded cross-linked sample. Niosome loading into the protein gel matrix increased its swelling extent in the enzyme-free simulated gastric fluid.

The effect of the addition of selected phenolic acids on the rheological properties of heated solutions of whey proteins

This study measured the flow behaviour of whey protein isolate mixtures with cinnamic or ferulic acids. Samples were heated in a vacuum (80 °C, –0.9 atm, 280 r.p.m., 0.5 h). The flow curves of all samples showed a non- Newtonian shear thinning flow and the viscoelastic properties were typical for weak gel systems. At pH 6.0, 6.7, and 8.0, the highest shear stress values were obtained with 20, 40, and 40 mg of cinnamic acid g–1 protein, respectively. At pH 6.0, the use of ferulic acid (20 mg g–1 protein) resulted in the elevation of shear stress values, but at pH 8.0, ferulic acid caused a decrease in shear stress values in comparison to cinnamic acid. The thixotropic area (AT) was increased in mixtures containing 20–40 mg cinnamic acid g–1 protein (at pH 6.7) and 20 mg of cinnamic acid g–1 protein (at pH 6.0). Similarly, the addition of ferulic acid (40 and 20 mg g–1 protein at pH 6.7 and 6.0, respectively) caused a significant increase in AT. At pH 8.0, no significant differences in AT values were observed between samples. Such systems can be applied with reference to health promoting foods such as WPI-based desserts.

Reducing the oil content in coated and deep‐fried chicken using whey protein

Whey protein has been investigated for its oil barrier properties in fried foods. Whey protein has been implemented successfully non‐film forming applications to reduce the fat content of deep‐fried chicken. As a 10% postbreading dip, whey protein solutions significantly lowered oil absorption of boneless patties by 37% compared to undipped controls. In bone‐in chicken thighs, 10% whey protein postbreading dip caused a 15% reduction in oil absorption during frying which was doubled by 10% β‐lactoglobulin postbreading dip at pH 2. A 30% lipid reduction was observed in deep‐fried battered and floured chicken strips when the strips were dipped in a 10% solution of denatured whey protein prior to frying compared to control chicken strips. When added to the batter of deep‐fried chicken nuggets, a significant fat reduction was observed for nuggets to which 3% whey protein was added to the batter compared to the control. In chicken strips that were marinated in a 15% solution of whey protein, a 35% fat reduction was observed. In spite of these results, questions that still remain. These studies have been undertaken in fully cooked products, not in raw coated or par‐fried products. The impact of rethermalization method is not known. Only preliminary research on the impact of WPI on the frying oil with respect to the formation of polar materials has been undertaken. On the positive side, the processes for introducing whey protein as an oil inhibition agent utilize processing steps that are already very common, e.g. incorporation into the batter or a marinade. Whey protein has the potential to be employed as an oil inhibiting agent in fried foods especially as it is relatively inexpensive and easy to come by.

Concentrated whey protein ingredients: A Fourier transformed infrared spectroscopy investigation of thermally induced denaturation

Thermal denaturation of whey protein solutions was investigated from a structural perspective utilising attenuated total reflectance – Fourier transformed infrared spectroscopy (ATR‐FTIR). Solutions (100 g protein/L, pH 7) of commercial whey protein isolate (WPI) powders and enriched protein fractions of β‐lactoglobulin (β‐lg) and α‐lactalbumin (α‐la) were heat‐treated at temperatures of 50–90 °C. Subsequent analysis by ATR‐FTIR highlighted the structural changes occurring as a direct result of heat treatments. Molecularly, WPI dispersions exhibited pronounced differences in denaturation behaviour depending on their method of manufacture. ATR‐FTIR is an informative tool to discern the structural molecular interactions not apparent through physical analysis of concentrated ingredients.

Thermal denaturation kinetics of whey proteins at high protein concentrations

A detailed kinetic study of the thermal reaction kinetics of whey protein concentrate was conducted at high protein concentrations. Whey protein solutions with protein concentrations of up to 40% (w/w) were heated at different temperatures for varying periods of times. The denaturation of β-lactoglobulin followed a reaction order of 1.5 and depended strongly on temperature and protein concentration. The rate of denaturation was shown to increase with increasing temperature. This could be explained by the strong influence of the temperature on the unfolding reaction. Furthermore, the protein concentration induced a faster thermal denaturation, most likely due to the increased probability of collision between whey protein molecules with increasing protein concentration which promotes protein aggregation. The results of this study are of industrial relevance for extrusion processes and the production of protein concentrates in evaporators where high protein concentrations are frequently used.

Effect of different types of nutrient solution on preoperative fasting time

Objective To discuss the feasibility of preoperative diet by measuring gastric emptying time of carbohydrate and protein nutrient solutions in healthy volunteers. Methods A total of 20 healthy volunteers were collected from August 2013 to May 2014. On the morning of the trial, baseline gastric residual volume of each volunteer was measured with magnetic resonance imaging at 8 a. m., then each of the 20 healthy volunteers took 12.5% carbohydrate solution 400 ml (containing 40 g of maltodextrin and 10 g of sucrose) or 12.5% whey protein solution (containing 50 g whey protein) in 5 minutes. Magnetic resonance imaging was conducted to measure the gastric residual volume every 25 minutes. The volunteers were shifted to the other nutrient solution after a 1-week interval. The gastric emptying time of both nutrient solutions was calculated to generate the curves illustrating the process of gastric emptying. Results The baseline gastric residual volume of the volunteers was (14.90±9.39) ml. The total gastric emptying time of carbohydrate solution was (104.90±27.98) min (95% CI 98.64-111.16 min), while that of whey protein solution was (199.6±34.17) min (95% CI 184.47-214.73 min). There was a significant difference between these two types of nutrient solution in terms of gastric emptying time (P<0.000 1). Conclusions The induction of anesthesia could be performed 2 hours after carbohydrate administration, and at least 4 hours after whey protein administration. Key words: Carbohydrate solution; Whey protein solution; Preoperative fasting; Gastric emptying; Magnetic resonance imaging

Effects of Grape Seed Powder and Whey Protein on Quality Characteristics of Chicken Nuggets

AbstractIn this study, two different treatments and their effects on quality characteristics of chicken nuggets after three different cooking procedures were evaluated. Batters containing grape seed powder (GSP) dipped into whey protein solution (WPS) were compared with control (without any treatment) using deep fat frying, conventional oven and microwave oven. Batters contained equal amounts of wheat and corn flours with 5 and 10% GSP. All batters exhibited thixotropic behavior, and the GSP enhanced batters had lower viscosities. The lowest pickup values and highest total color change (ΔE) values were observed in deep fat fried samples. The microwaved samples had higher crispness levels and pickup values but achieved lighter colors that were identical to those of the pre‐fried samples. Samples dipped into WPS provided reduced oil absorption consistent with their moisture contents. The scores for overall acceptability tended to decrease with the increase in GSP amount.Practical ApplicationsThis study shows the effects of grape seed and whey protein solution treatments on batter quality as well as their interaction with cooking procedures. Although negative impressions toward battered and fried food products have been increased, consumers are becoming aware of health and nutritional food concepts. Therefore, new strategies are necessary in order to obtain healthier battered and fried foods without compromising the sensory quality. Grape seed powder is a promising ingredient as well as whey protein solution treatment as a post dip for improving the major components of frying batter in terms of textural properties, flow behavior, oil uptake and batter pickup. The results of this study could be helpful in the development of novel fried nuggets that include natural antioxidants having similar characteristics with grape seed powder.

Effects of protein addition to carbohydrate–electrolyte solutions on postexercise rehydration

Background/ObjectiveThis study aimed to examine the effects of the addition of whey or casein protein, the two major proteins in milk, to carbohydrate–electrolyte (CE) solutions on postexercise rehydration. MethodsTen young men aged 20.7 ± 1.4 years with an average VO2max of 60.7 mL/kg/min ran for 60 minutes at 65% VO2max on three occasions followed by 4 hours' recovery. During recovery, the participants consumed either CE solution with 66 g/L carbohydrate (CHO), or CE plus whey protein solution (CW trial, 44 g/L CHO, 22 g/L whey), or CE plus casein protein solution (CC trial, 44 g/L CHO, 22 g/L casein); the solutions were matched for energy and electrolyte content. ResultsThe participants lost 2.36 ± 0.32% of their pre-exercise body weight after the exercise. Total urine output after recovery was greater in the CE and CC trials than CW trial (CE vs. CW vs. CC: 1184 ± 378 mL vs. 1005 ± 214 mL vs. 1256 ± 413 mL; p < 0.05). Fluid retention after ingestion of CW solution was greater than CE and CC solutions (CE vs. CW vs. CC: 46.9 ± 16.5% vs. 54.9 ± 9.2% vs. 45.8 ± 17.3%; p < 0.05). Lower urine specific gravity and urine osmolality were observed by the end of recovery in the CE trial compared with CW trial (p < 0.05). No difference was found in the changes in plasma volume in all trials. ConclusionThese results suggest that during the 4 hours' recovery after a 60-minute run, the CW solution was more effective for rehydration compared with the CE or CC solution.

Effect of heating whey proteins in the presence of milk fat globule membrane extract or phospholipids from buttermilk

The objective of this study was to determine the contribution of phospholipids from buttermilk as a nucleus in the heat-induced aggregation of whey proteins. Solutions of whey proteins (5%, w/v) were adjusted to pH 4.6 or 6.8 and then heated at 65 or 80 °C for 25 min with or without 1% (w/v) of milk fat globule membrane (MFGM) extract or phospholipid powder. The aggregation mechanisms were characterised using analysis with Ellman's reagent, one-dimensional gel electrophoresis, thin-layer chromatography, and three-dimensional confocal laser-scanning microscopy. Three-dimensional images showed protein/phospholipid interactions in the presence of MFGM extract or phospholipids, and thin-layer chromatography plates showed no trace of free phospholipids after 20 min at pH 4.6. Overall, the results demonstrate that phospholipids from buttermilk were involved in the formation of protein aggregates through the MFGM fragments at a low temperature, whereas phospholipids could interact directly with the proteins at a higher temperature (80 °C).

Effect of high pressure - low temperature processing on composition and colloidal stability of casein micelles and whey proteins

The aim of this study was to identify the impact of high pressure treatments at sub-zero temperatures (high pressure - low temperature; HPLT) on milk proteins. Whey protein solutions, micellar casein dispersions and two mixtures (micellar caseins:whey proteins, 80:20 and 20:80, w/w) were pressure treated (100–600 MPa) at pH 7.0 or 5.8 at −15 °C, −35 °C and ambient temperature. Solubility data showed that whey proteins could only be affected by HPLT treatments at pH 7.0 if caseins were present, while effects could be induced at pH 5.8 without the presence of caseins. The caseins formed on the one hand large aggregates (flocs) and on the other hand the solubility was increased by the creation of smaller micelles. The formation of flocs could only be observed for HPLT treated samples, which indicates the formation of different protein interactions in milk protein based samples compared with common HP treatments.

Leucine-enriched protein feeding does not impair exercise-induced free fatty acid availability and lipid oxidation: beneficial implications for training in carbohydrate-restricted states.

Given that the enhanced oxidative adaptations observed when training in carbohydrate (CHO)-restricted states is potentially regulated through free fatty acid (FFA)-mediated signalling and that leucine-rich protein elevates muscle protein synthesis, the present study aimed to test the hypothesis that leucine-enriched protein feeding enhances circulating leucine concentration but does not impair FFA availability or whole body lipid oxidation during exercise. Nine males cycled for 2 h at 70% VO2peak when fasted (PLACEBO) or having consumed a whey protein solution (WHEY) or a leucine-enriched whey protein gel (GEL), administered as 22 g 1 h pre-exercise, 11 g/h during and 22 g 30 min post-exercise. Total leucine administration was 14.4 g and 6.3 in GEL and WHEY, respectively. Mean plasma leucine concentrations were elevated in GEL (P = 0.001) compared with WHEY and PLACEBO (375 ± 100, 272 ± 51, 146 ± 14 µmol L(-1), respectively). No differences (P = 0.153) in plasma FFA (WHEY 0.53 ± 0.30, GEL 0.45 ± 0.25, PLACEBO 0.65 ± 0.30, mmol L(-1)) or whole body lipid oxidation during exercise (WHEY 0.37 ± 0.26, GEL 0.36 ± 0.24, PLACEBO 0.34 ± 0.24 g/min) were apparent between trials, despite elevated (P = 0.001) insulin in WHEY and GEL compared with PLACEBO (38 ± 16, 35 ± 16, 22 ± 11 pmol L(-1), respectively). We conclude that leucine-enriched protein feeding does not impair FFA availability or whole body lipid oxidation during exercise, thus having practical applications for athletes who deliberately train in CHO-restricted states to promote skeletal muscle adaptations.

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.

Decoupling macronutrient interactions during heating of model infant milk formulas.

Understanding macronutrient interactions during heating is important for controlling viscosity during infant milk formula (IMF) manufacture. Thermal behavior of macronutrients (casein, whey, lactose, fat) was studied, in isolation and combination, over a range of concentrations. Addition of phosphocasein to whey protein solutions elevated denaturation temperature (Td) of β-lactoglobulin and the temperature at which viscosity started to increase upon heating (Tv). Secondary structural changes in whey proteins occurred at higher temperatures in dispersions containing phosphocasein; the final extent of viscosity increase was similar to that of whey protein alone. Addition of lactose to whey protein solutions delayed secondary structural changes, increased Td and Tv, and reduced post heat treatment viscosity. This study demonstrated that heat-induced changes in IMF associated with whey protein (denaturation, viscosity) are not only a function of concentration but are also dependent on interactions between macronutrients.

Foam preparation at high-throughput using a novel packed bed system

We investigated the formation of food foams using a novel packed bed system at different operating pressures. The foaming process was based on simultaneous injection of continuous (whey protein solution) and dispersed (nitrogen gas) phases into a column containing a packed bed of glass beads. Bubbles were produced by entrapment of nitrogen by thin films of continuous phase inside the porous medium. Initial results show a proof of principle that the proposed system can be an effective method for the controlled production of foams at overruns of up to 600%. The entire window of operation regarding all process and formulation possibilities is expected to be much wider but needs to be established in future research.

Efficacy of Lactoperoxidase System-Whey Protein Coating on Shelf-life Extension of Rainbow Trout Fillets During Cold Storage(4 °C)

The growth and metabolism of gram-negative microorganisms are widely recognized as important reasons for the spoilage of fish and fish product. Based on antimicrobial activity of lactoperoxidase system (LPOS) against gram-negative bacteria, the present study investigated the effect of incorporation of LPOS at concentrations 0 (control), 1.25, 2.5, 5 and 7.5 % (v/v) into whey protein solution as novel antimicrobial coating strategy for rainbow trout (Oncorhynchus mykiss) preservation under refrigeration temperature (4 ± 1 °C) over a 16-day period. During storage of trout fillets, control and 1.25 % LPOS-treated samples reached undesirable levels of rancidity (p < 0.05) at 12th and 16th days, respectively, whereas the higher concentrations showed to be more efficiently stable (p < 0.05) in sensory, chemical (total volatile basic nitrogen (TVB-N) and pH) and microbiological analyses (mesophilic bacteria, psychrotrophic bacteria, Pseudomonas spp. and specific spoilage bacteria). Lipid oxidation in the fillets was not affected significantly by LPOS treatment. The LPOS-whey protein coating also reduced total specific spoilage organisms (Shewanella putrefaciens and Pseudomonas fluorescens) of the fillets more than 1.5 log by the end of storage. The shelf life of samples was extended approximately from 12 days to at least 16 days in the presence of the LPOS. These results indicated the significant antimicrobial activity of the LPOS-whey protein coating solution for refrigerated fish fillets.

Nanoparticulation of enzymatically cross-linked whey proteins to encapsulate caffeine via microemulsification/heat gelation procedure

A co-surfactant free microemulsion was formulated with sunflower oil, span 80 and whey protein solution and used as nanoreactor to generate caffeine-enveloping capsules through heat gelation of protein. Transglutaminase-induced cross-linking of proteins prior to microemulsification decreased the mean diameter from 478 to 318 nm for core-free particles and from 232 to 118 nm for capsules. As well, the lower limit of capsules size decreased from 78 nm to 45 nm due to enzymatic cross-linking. Scanning electron microscopy showed that morphology of particles and capsules was not completely spherical which was attributed to the protrusion of protein molecules out of aqueous droplets during gelation. The enzymatic treatment yielded in particles with higher glass transition temperature due to the reinforced structure of particulate gel. Fourier transform infrared spectroscopy confirmed the structural changes in proteins by heat and establishment of covalent cross-linkages by the enzyme action manifested by a band at 1078 cm−1.

Effects of Emulsification of Fat on the Surface Tension of Protein Solutions and Surface Properties of the Resultant Spray-Dried Particles

To examine the effect of protein adsorption on the fat–water interface on the surface composition of spray-dried particles, whey, hydrolyzed whey, and soy protein isolate emulsions were prepared at three different protein to fat ratios of 1:1, 1:5, and 1:10 and spray dried. Non-hydrolyzed whey protein isolate (WPI) and the more hydrolyzed whey protein solutions at 20.2% degree of hydrolysis (DH) had significantly lower surface tension values with fat than without fat. The correlation between the reduction of surface tension value of an emulsion and the increase in protein surface composition of powder particles was observed for WPI and HWP406 but was not observed for the other protein isolate types. It was clear that the spray-dried emulsions had fat as the dominant component on the surface of the powder particles and that the amount of protein on the surface became severely depressed at higher fat addition levels. In terms of its powder morphology, the unique powder structures such as the indentations and folds usually found on the surface of protein containing powders were not evident because they were compromised by the presence of high surface fat. The powder with higher surface fat had more crumpled particle structures and dimpled surfaces.

The use of ultrasonic feed pre-treatment to reduce membrane fouling in whey ultrafiltration

The production of whey protein concentrate powders is often limited by the fouling of the ultrafiltration membranes and the low heat stability of the whey protein solutions. Ultrasonic treatment of whey solutions has previously been shown to break down protein aggregates and improve heat stability. This study investigates the use of ultrasound as a pre-treatment step to improve downstream ultrafiltration performance. Results show that sonication alone alleviated membrane fouling to a small extent. However, the use of ultrasound following heat exposure reduced membrane pore blockage and growth of the foulant cake greatly, relative to heat exposure in the absence of ultrasound. The extent of changes to pore blockage and cake growth was greater at higher solids concentration. In all cases, the protein concentration in the permeate remained unchanged. This work has the potential to reduce energy requirements in the ultrafiltration of whey as feed pre-treatment by both ultrasound and the combination of heat and ultrasound produced a lower viscosity feed solution.

Characterization of Rheological and Molecular Properties of Whey Protein Thickeners

The production of whey protein thickeners by drying protein gels to produce instant thickening powders has been previously investigated. The use of native whey proteins as a food thickener, however, has not been studied earlier. In this work, we characterized thermally treated whey protein solutions with improved thickening properties. Viscosity contour maps were constructed to outline the viscosity values at different protein and salt concentrations. Huggins-Kraemer constants revealed that at low ionic strengths, polymerized protein molecules behave as flexible coils, while at higher ionic strengths, molecules appear to be aggregated in a spherical like shape.

Composition of milk fouling deposits in a plate heat exchanger under pulsed flow conditions

Fouling deposition on heat exchangers in milk plants is the main reason of progressive decline in efficiency and performance during operation. In order to increase operational effectiveness an anti-fouling strategy based on the adjustment of the hydrodynamic flow conditions was investigated. For this purpose stationary flow was superimposed by an oscillating flow, resulting in temporary high values of the wall shear stress. Experiments were conducted using a commercial stainless steel pilot scale plate heat exchanger (PHE) with a calcium phosphate-rich whey protein solution as model fluid. The PHE system was operated at a product side flow rate of 0.085m3h−1 (v=0.1ms−1, Re=870) heating the solution from 62 to 85°C. The results show that the build-up of fouling layers as well as the fouling layer composition was strongly dependent on the flow conditions. The pulsation amplitude and mode mainly influenced the mineral deposition and a reduction of fouling was achieved. Hence, the use of pulsed flow provides an opportunity for the mitigation of milk fouling.