Effect of incorporating whey protein concentrate into stevia‐sweetened Kulfi on physicochemical and sensory properties

In 50% sugar replaced with 0.05% stevia‐added Kulfi, whey protein concentrate (WPC) at 0, 2, 3 and 4% levels were separately incorporated. Increase in WPC level resulted in significant (P < 0.05) decrease in freezing point, melting rate, hardness and moisture percentage and significant (P < 0.05) increase in specific gravity, protein percentage and total calorie content in the product. Among 0, 2, 3 and 4% WPC‐added Kulfi, 3% WPC‐added Kulfi was adjudged as best by a panel of judges. Above 3% WPC addition, the product was very soft and possessed undesirable whey flavour.     

Lowering the Maillard reaction products (MRPs) in heated whey protein products and their cytotoxicity in human cell models by whey protein hydrolysate

This study investigated the potential use of reconstituted whey protein hydrolysate as an antibrowning agent in thermally processed foods and as a chemopreventive ingredient in biological systems. Hydrolysates were prepared by tryptic (EC 3.4.21.4) hydrolysis of whey protein concentrate (WPC) or heated (80 °C for 30 min) whey protein concentrate (HWPC). Tryptic hydrolysis of WPC and HWPC increased the oxygen radical absorbance capacity-fluorescein (ORAC_FL) antioxidant capacity from 0.2 to 0.5 ??mol Trolox equivalent (TE)/mg protein in both whey protein hydrolysate (WPH) and heated whey protein hydrolysate (HWPH) (p < 0.05). The reconstituted WPH and HWPH could prevent the formation of Maillard reaction products (MRPs) induced by a thermal process employed on WPC suspensions between 80 and 121 °C in the presence of lactose up to 0.25 M (p < 0.05). The MRPs in HWPC were cytotoxic to both normal human intestinal FHs 74 Int cells and human epithelial colorectal carcinoma Caco-2 cells. The IC₅₀ of HWPC was around 3.18-3.38 mg/mL protein. Nonetheless, when both cell types were grown in media supplemented with WPH prior to the uptake of MRPs in HWPC at 3.5 mg/mL, they were able to survive (p < 0.05). Overall, this study indicated the efficacy of WPH and HWPH in the prevention of MRP cytotoxicity. It was suggested that the ORAC_FL antioxidant capacity of WPH and HWPH needed to be high enough to provide a chemopreventive effect against MRP cytotoxicity.     

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.     

Viscoelastic properties of caseinmacropeptide isolated from cow,ewe and goat cheese whey

Caseinmacropeptide (CMP) is a C‐terminal glycopeptide released from κ‐casein by the action of chymosin during cheese‐making. It is recognised as a bioactive peptide and is thought to be an ingredient with a potential use in functional foods. CMP occurs in sweet cheese whey and whey protein concentrate (WPC). Its composition is variable and depends on the particular whey source and the fractionation technology employed in the isolation. There were no significant (P < 0.05) differences in the relative apparent viscosities between species of CMPs (cow, ewe and goat). Analyses at different pH (2, 4, 7, 10), ionic strength (0, 0.2, 0.4 and 0.7 as NaCl molarity) and protein concentration (50, 100 and 200 g kg^?1) at temperatures from 10 to 90 °C carried out found pH 7 and high protein concentration (200 g kg^?1) conditions to be the best for CMP solutions to keep low and constant relative viscosity values with increasing temperature up to 75 °C. The viscoelastic properties–storage modulus, loss modulus and phase angle–of the different CMPs and WPC solutions were determined. Heat‐induced rheological changes in CMP solutions occurred at moderate temperatures (40–50 °C) with no appreciable differences in viscosity. Gelation took place significantly (P < 0.05) earlier in goat CMP (41 °C), followed by cow CMP (44 °C), ewe CMP (47 °C) and WPC (56 °C). Heating at 90 °C showed that WPC required significantly (P < 0.05) longer times to form gels (>5 min) than the CMPs (<5 min). WPC gels had higher (>20°) phase angle than CMP (<20°), which could be associated with untidy structures, limiting elastic properties of the gel. Copyright © 2006 Society of Chemical Industry     

Whey protein concentrate/λ-carrageenan systems: Effect of processing parameters on the dynamics of gelation and gel properties

The thermal characteristics, dynamics of gelation and gel properties of commercial whey protein concentrate (WPC), WPC/λ-carrageenan (λ-C) mixtures (M) and WPC/λ-C spray-dried mixtures (DM) have been characterized. In a second stage, the effect of the gelling variables (T, pH, total solid content) on gelation and textural properties of DM was evaluated through a Doehlert uniform shell design.The presence of λ-C either in mixtures (M) or in DM promoted the WPC gelation at lower concentration (8%). M showed higher rates of formation and better gel properties (higher hardness, adhesiveness, springiness and cohesiveness) than DM.Nevertheless, when the effects of pH (6.0–7.0), heating temperature (75–90 °C) and total solid content (12–20 wt%) on gelation dynamics and gel properties of DM were studied, gels with a wide range of rheological and textural properties were obtained. While pH did not affect the gelation dynamics, it had some effect on rheological and textural properties. Total solid content and heating temperature were the most important variables for the dynamics of gelation (gelation rate (1/t_gel), gelation temperature (T_gel), rate constant of gel structure development (k_G), elastic modulus after cooling (G′_c) and textural parameters (hardness, springiness and cohesiveness).     

Effects of caseinate, whey and milk powders on the texture and microstructure of emulsified chicken meat batters

The effects of adding dry caseinate, whole milk, skim milk, regular, and modified whey protein powders, at a level of 2 g/100 g, to meat batters were studied. All dairy additives, except for the regular whey, significantly reduced cook loss (30-50% reduction). Caseinate and modified whey formed distinct dairy protein gel regions within the meat batters, as revealed by light microscopy. Both also contributed more to enhancing the textural properties of the meat batters compared to the other dairy proteins; i.e., increasing texture profile analysis fracturability, and hardness, respectively. Overall, the most cost-effective ingredient appeared to be the modified whey, which also provided the best moisture retention.     

Effects of oxidase and protease treatments on the breadmaking functionality of a range of gluten-free flours

In this study, the application of glucose oxidase and protease commercial preparations was investigated in order to evaluate their impact on the breadmaking performance of four different gluten-free flours (buckwheat, corn, sorghum and teff). Bread formulas were developed without addition of hydrocolloids in order to avoid synergistic effects. Glucose oxidase improved corn (CR) and sorghum (SG) bread quality by increasing specific volume (P < 0.05) and reducing collapsing at the top. The improvements could be related to protein polymerization which resulted in enhanced continuity of the protein phase and elastic-like behavior of CR and SG batters. No significant effects were detected on buckwheat (BW) and teff breads. On the other hand, protease treatment had detrimental effects on the textural quality of BW and SG breads. The effects were related to protein degradation resulting in increased liquid-like behaviour of BW and SG batters. Overall, the results of this study suggest that protein polymerisation can improve the breadmaking performance of gluten-free flours by enhancing elastic-like behaviour of batters. However, the protein source is a key element determining the impact of the enzymes. In the absence of hydrocolloids, protein structures are important to ensure the textural quality of these types of breads.     

Crust and crumb characteristics of gluten free breads

Gluten free breads often have poor crust and crumb characteristics and the current study was conducted to help alleviate this problem. A commercial wheat starch (Codex Alimentarius) gluten free flour was supplemented with seven dairy powders (0%, 3%, 6%, 9% inclusion rates based on flour weight). Initially a fixed water level was used (trial 1) and the resulting batters were proofed and baked. The breads were tested 24 h after baking. Powder addition reduced loaf volume by circa 6% (P<0.001). Increasing the inclusion levels of the powders decreased loaf volume (P<0.001) with a decrease of 8% for the highest level. Powder addition generally decreased the crumb L^*/b^* (white/yellow) ratio. Crust L^* values were significantly reduced. All of the powders increased crumb hardness (P<0.001) with the exception of demineralised whey powder. Ten and 20% additional water (trial 2) was added to the formulation and the resulting breads had higher volume, and a much softer crust and crumb texture. Sensory analysis revealed a preference for breads containing skim milk replacer, sodium caseinate and milk protein isolate.     

Short communication: Sensitive detection of norbixin in dried dairy ingredients at concentrations of less than 1 part per billion

Norbixin is the water-soluble carotenoid in annatto extracts used in the cheese industry to color Cheddar cheese. The purpose of norbixin is to provide cheese color, but norbixin is also present in the whey stream and contaminates dried dairy ingredients. Regulatory restrictions dictate that norbixin cannot be present in dairy ingredients destined for infant formula or ingredients entering different international markets. Thus, there is a need for the detection and quantification of norbixin at very low levels in dried dairy ingredients to confirm its absence. A rapid method for norbixin evaluation exists, but it does not have the sensitivity required to confirm norbixin absence at very low levels in compliance with existing regulations. The current method has a limit of detection of 2.7 μg/kg and a limit of quantification of 3.5 μg/kg. The purpose of this study was to develop a method to extract and concentrate norbixin for quantification in dried dairy ingredients below 1 μg/kg (1 ppb). A reverse-phase solid-phase extraction column step was applied in the new method to concentrate and quantify norbixin from liquid and dried WPC80 (whey protein concentrate with 80% protein), WPC34 (WPC, 34% protein), permeate, and lactose. Samples were evaluated by both methods for comparison. The established method was able to quantify norbixin in whey proteins and permeates (9.39 μg/kg to 2.35 mg/kg) but was unable to detect norbixin in suspect powdered lactose samples. The newly developed method had similar performance to the established method for whey proteins and permeates but was also able to detect norbixin in powdered lactose samples. The proposed method had a >90% recovery in lactose samples and a limit of detection of 28 ppt (ng/kg) and a limit of quantification of 94 ppt (ng/kg). The developed method provides detection and quantification of norbixin for dairy ingredients that have a concentration of <1 ppb.     

Changes in physicochemical and functional properties of whey protein concentrate upon succinylation

The highest degree of succinylation was achieved at the level of 6 moles of succinic anhydride/mole of lysine in whey protein concentrate (WPC). Structural modification of protein or the presence of a high negative charge on the surface of protein upon succinylation exposed buried hydrophobic sites. The solubility of succinylated protein derivatives increased at alkaline pH but decreased at acidic pH values as compared to native WPC. The physicochemical properties of succinylated protein derivatives, such as water– and oil– binding capacity, viscosity and emulsion properties increased significantly (P < 0.05) compared to native WPC, whereas, foaming stability reduced significantly (P < 0.05) and there was no change in the foaming capacity.     

Texturized Dairy Proteins

ABSTRACT: Dairy proteins are amenable to structural modifications induced by high temperature, shear, and moisture; in particular, whey proteins can change conformation to new unfolded states. The change in protein state is a basis for creating new foods. The dairy products, nonfat dried milk (NDM), whey protein concentrate (WPC), and whey protein isolate (WPI) were modified using a twin-screw extruder at melt temperatures of 50, 75, and 100 °C, and moistures ranging from 20 to 70 wt%. Viscoelasticity and solubility measurements showed that extrusion temperature was a more significant (P < 0.05) change factor than moisture content. The degree of texturization, or change in protein state, was characterized by solubility (R²= 0.98). The consistency of the extruded dairy protein ranged from rigid (2500 N) to soft (2.7 N). Extruding at or above 75 °C resulted in increased peak force for WPC (138 to 2500 N) and WPI (2.7 to 147.1 N). NDM was marginally texturized; the presence of lactose interfered with its texturization. WPI products extruded at 50 °C were not texturized; their solubility values ranged from 71.8% to 92.6%. A wide possibility exists for creating new foods with texturized dairy proteins due to the extensive range of states achievable. Dairy proteins can be used to boost the protein content in puffed snacks made from corn meal, but unmodified, they bind water and form doughy pastes with starch. To minimize the water binding property of dairy proteins, WPI, or WPC, or NDM were modified by extrusion processing. Extrusion temperature conditions were adjusted to 50, 75, or 100 °C, sufficient to change the structure of the dairy proteins, but not destroy them. Extrusion modified the structures of these dairy proteins for ease of use in starchy foods to boost nutrient levels. Practical Application: Dairy proteins can be used to boost the protein content in puffed snacks made from corn meal, but unmodified, they bind water and form doughy pastes with starch. To minimize the water binding property of dairy proteins, whey protein isolate, whey protein concentrate, or nonfat dried milk were modified by extrusion processing. Extrusion temperature conditions were adjusted to 50, 75, or 100 °C, sufficient to change the structure of the dairy proteins, but not destroy them. Extrusion modified the structures of these dairy proteins for ease of use in starchy foods to boost nutrient levels.     

The Potential Source of B. licheniformis Contamination During Whey Protein Concentrate 80 Manufacture

The objective of this study was to determine the possible source of predominant Bacillus licheniformis contamination in a whey protein concentrate (WPC) 80 manufacturing plant. Traditionally, microbial contaminants of WPC were believed to grow on the membrane surfaces of the ultrafiltration plant as this represents the largest surface area in the plant. Changes from hot to cold ultrafiltration have reduced the growth potential for bacteria on the membrane surfaces. Our recent studies of WPCs have shown the predominant microflora B. licheniformis would not grow in the membrane plant because of the low temperature (10 °C) and must be growing elsewhere. Contamination of dairy products is mostly due to bacteria being released from biofilm in the processing plant rather from the farm itself. Three different reconstituted WPC media at 1%, 5%, and 20% were used for biofilm growth and our results showed that B. licheniformis formed the best biofilm at 1% (low solids). Further investigations were done using 3 different media; tryptic soy broth, 1% reconstituted WPC80, and 1% reconstituted WPC80 enriched with lactose and minerals to examine biofilm growth of B. licheniformis on stainless steel. Thirty‐three B. licheniformis isolates varied in their ability to form biofilm on stainless steel with stronger biofilm in the presence of minerals. The source of biofilms of thermo‐resistant bacteria such as B. licheniformis is believed to be before the ultrafiltration zone represented by the 1% WPC with lactose and minerals where the whey protein concentration is about 0.6%.     

Emulsification of Commercial Dairy Proteins with Exhaustively Washed Muscle

The addition of dairy proteins to exhaustively washed chicken breast muscle improved the emulsion stability in heated cream layers (emulsions) containing whey protein concentrate (WPC) or whey protein isolate (WPI). The initial weight of the heated cream layers made with WPC or WPI was heavier than those for sodium caseinate (CNate) or milk protein isolate (MPI). The addition of CNate or MPI resulted in decreased emulsion stability and increased inhibition of myosin heavy chain and actin participation in the emulsion formation compared to WPC or WPI.     

Effects of various whey proteins on the physicochemical and textural properties of set type nonfat yoghurt

In this study, the changes during storage in the physicochemical, textural and sensory properties of nonfat yoghurts fortified with whey proteins, namely whey protein concentrates (WPC), whey protein isolates and whey protein hydrolysates, were investigated. Enrichment of nonfat yoghurt with the whey protein additives (1% w/v) had a noticeable effect on pH, titratable acidity, syneresis, water‐holding capacity, protein contents and colour values on the 14th day of storage (P < 0.01). The addition of whey proteins to the yoghurt milk led to increases in the hardness, cohesiveness and elasticity values, resulting in improved textural properties. The addition of WPC improved the texture of set‐type nonfat yoghurt with greater sizes in the gel network as well as lower syneresis and higher water holding capacity. This study suggests that the addition of whey protein additives used for fortification of yoghurt gave the best textural and sensory properties that were maintained constant during the shelf life.     

The effect of untreated and enzyme-treated commercial dairy powders on the growth and adhesion of Streptococcus mutans

Dental caries is a common bacterial infection, but the progression of this disease can be delayed by preventing initial attachment of cariogenic bacteria such as Streptococcus mutans to tooth surfaces. This study firstly compares the effect of untreated (UT) and enzyme-treated (ET) dairy powders on the adherence of S. mutans to hydroxylapatite (HA), an analogue of tooth enamel. A fluorescence-based method was used to quantify adherence of S. mutans to HA both in the presence (S-HA) and absence (PBS-HA) of saliva. Secondly, binding of proteins present in the test materials to HA was quantified using bicinchonic acid assays and SDS-PAGE. In addition, the effect of UT and ET dairy powders on growth of S. mutans was examined using an optical-density based assay. UT acid whey protein concentrate (WPC) 80, sweet WPC80, buttermilk powder (BMP) and cream powder (CP) significantly (P < 0.05) inhibited adhesion of S. mutans at ≥31.25 μg mL⁻¹ in the presence and absence of saliva. ET dairy powders were less effective inhibitors of adhesion, but ET sweet WPC80 significantly (P < 0.05) inhibited growth of S. mutans at ≥0.6 mg mL⁻¹. Therefore, due to their adherence- and growth-inhibitory properties, dairy powders may be beneficial in the treatment of dental caries.     

Effects of protein and transglutaminase on the preparation of gluten-free rice bread

Effects of transglutaminase (TGase) and proteins such as whey protein, caseinate, and soy protein on the preparation of gluten-free rice breads using non-waxy rice flour were investigated. Rice flour (about 12% moisture content) was prepared from dry milling of dried grain after rice got soaked. Unlike general dry milled flour, newly developed rice flour increased water binding capacity (WBC), swelling power, and peak viscosity. Soy protein increased WBC but other proteins slightly decreased with the increase of levels. Lightness decreased and yellowness increased with the addition of whey and soy protein. All pasting viscosities decreased with the addition of protein. The TGase improved the network structure of rice batter. The 2^nd proof time of rice batter with protein was shortened by 4–9 min with the addition of TGase. The specific volumes of rice breads with whey and soy protein also increased. TGase and protein additions decreased the hardness of rice bread. Sensory test showed that roasted flavor, volume, air cell homogeneity, and overall quality were significantly different (p<0.05) with protein and TGase additions.     

Use of ultrafiltration and supercritical fluid extraction to obtain a whey buttermilk powder enriched in milk fat globule membrane phospholipids

Whey buttermilk, a by-product from whey cream processing to butter, is rich in milk fat globule membrane (MFGM) constituents, which have technological and potential health properties. The objective of this work was to produce a dairy ingredient enriched in MFGM material, especially phospholipids, from whey buttermilk. Whey buttermilk was concentrated by ultrafiltration (10×) and subsequently diafiltered (5×) (10 kDa molecular mass cutoff membrane) at 25 °C and the final retentate was spray-dried. The whey buttermilk powder was submitted to supercritical extraction (350 bar, 50 °C) using carbon dioxide. The membrane filtration removed most of the lactose and ash from the whey buttermilk, and the supercritical extraction extracted exclusively non-polar lipids. The final powder contained 73% protein and 21% lipids, of which 61% were phospholipids. This ingredient, a phospholipids-rich dairy powder, could be used as an emulsifier in different food systems.     

Proliferation and intracellular glutathione in Jurkat T cells with concentrated whey protein products

The effect of two whey protein concentrates (WPCs) and three whey protein isolates (WPIs) on the growth and intracellular glutathione concentration of Jurkat T cells was determined. Standard RPMI 1640 media containing foetal calf serum with no WPC or WPI supplementation was used as the control, while supplementation with N-acetyl cysteine—a known glutathione promoter—was included as a positive control. Both WPCs lowered the cell count-adjusted glutathione concentration following a 24 h incubation period and one significantly (p<0.05) increased cell proliferation. Only one of the three WPIs significantly (p<0.05) inhibited cell proliferation although its composition with respect to β-lactoglobulin, glycomacropeptide, α-lactalbumin, IgG, proteose peptone and BSA content was almost identical to another WPI, as determined by HPLC. Based on co-migration with standards under two different modes of chromatography, lactoferrin was detected in the WPI showing the inhibitory effect at a level of 0.4 mg mL⁻¹, but not in any of the other concentrated whey protein products. None of the whey protein products tested increased cell-adjusted intracellular glutathione concentration.