Functional Properties Of Whey Proteins Research Articles

Functional Properties of Edible Films Using Whey Protein Concentrate

Methodologies were developed to form edible films of simple proteins or protein-lipid composited using whey protein concentrate. The functional properties of whey protein concentrate films were compared with those of the films derived from sodium caseinate, potassium caseinate, calcium caseinate, and whey protein isolate. Water vapor permeability of simple whey protein concentrate film was lower than that for films of sodium caseinate, potassium caseinate, and whey protein isolate. Composite whey protein concentrate film had the lowest water vapor permeability of all the milk protein films. The ultimate tensile strengths of simple whey protein concentrate films were similar to those of caseinate films. Whey protein concentrate films exhibited lower puncture strengths than did films from other milk proteins except simple film from sodium caseinate. Whey protein concentrate and isolate films had higher elongation values than did simple calcium caseinate films. Transmission electron microscopy revealed the presence of residual milk fat embedded in the protein matrix in whey protein concentrate films. Whey protein concentrate films had good water vapor barrier and mechanical properties that were comparable with those of films from other commercial milk proteins.

Improvement of the Surface Functional Properties ofβ-Lactoglobulin andα-Lactalbumin by Heating in a Dry State

Controlled heating in a dry state greatly improved the surface functional properties of whey proteins (β-lactoglobulin and α-lactalbumin). Although whey proteins were completely insolubilized by heating at 80°C in an aqueous solution, their solubility was kept even after heating at 80°C in a dry state (7.5% moisture content) for 5 days. The surface hydrophobicity of α-lactalbumin was increased during the dry-heating, while that of β-lactoglobulin was decreased. In addition, the fluorescence spectra excited at 280 nm of dry-heated whey proteins suggested the significant conformational changes. High-performance gel chromatography showed that a considerable amount of soluble aggregates was formed in the dry-heated β-lactoglobulin, while a small amount of soluble aggregate was observed in the dry-heated α-lactalbumin. The foaming properties of dry-heated whey proteins were increased to about 3 times that of untreated proteins. The emulsifying properties of dry-heated whey proteins were also increased, compared to untreated proteins, although a slight decrease in the emulsion stability was observed in dry-heated β-lactoglobulin. The improvement of the surface properties seemed to come from the partial unfolding suitable for the formation of foam film and the entrapment of oil droplets.

Seasonal Changes in the Physical and Functional Properties of Whey Protein Concentrates

Seasonal variations have been monitored in the milk supply and in six physical and functional properties of commercial whey protein concentrate (75% protein) manufactured at intervals over a single lactation cycle in southeastern Australia. Recently, we reported that percentages of the major proteins in whey protein concentrate varied inversely; late season powders were characterized by a high proportion of β-lactoglobulin and a low proportion of α-lactalbumin. In the present study, transition energy associated with protein denaturation was reduced for whey protein concentrate prepared in the final 3 mo of lactation. This decrease paralleled a similar decrease in α-lactalbumin content and surface hydrophobicity of the whey protein concentrate. Other seasonal changes in the functional properties of whey protein concentrate included increased foaming capacity and decreased foam stability for whey protein concentrate prepared in the latter half of lactation. Heat-induced gel firmness was generally higher for whey protein concentrate manufactured in the final 3 mo of the lactation cycle, an observation that paralleled an increased proportion of β-lactoglobulin in whey protein concentrate prepared at that time.

Thermal Stability and Functionality of Whey Proteins

Functional properties of whey proteins are often impaired by inevitable heat treatments during processing of whey protein products and preservation of food products. The extent of deterioration depends on the relation between the rate of protein denaturation and the heat load applied. In a new kinetic approach, whey protein denaturation is split into two successive processes: 1) unfolding, determined by differential scanning calorimetry; and 2) aggregation, derived from high performance gel permeation chromatography.A short review is presented of industrial recovery processes of whey protein products and their related functional properties. The effect of heat treatments between 70 and 90°C is analyzed in terms of the kinetics of whey protein unfolding and aggregation. The results reveal that thermal denaturation of whey proteins during industrial heating processes is predictable. An important determinant for functional properties is the salt composition of whey protein products during heat treatments at temperatures above 75°C.

Effect of HTST Pasteurization of Milk, Cheese Whey and Cheese Whey UF Retentate upon the Composition, Physicochemical and Functional Properties of Whey Protein Concentrates

ABSTRACTThe effect of high temperature‐short time (HTST) pasteurization of milk, Cheddar cheese whey and cheddar cheese whey ultrafiltration (UF) retentate upon the composition, physicochemical and functional properties of whey protein concentrates (WPC) was investigated. HTST pasteurization (72°C‐15 sec) of milk, whey and UF retentate caused no significant differences in chemical composition of resulting WPCs. HTST pasteurization of milk and whey had no significant effect upon WPC solubility, whereas, heating UF retentate caused significant loss of WPC solubility. HTST pasteurization of milk caused a significant lowering (P<0.10) of maximum foam expansion of WPC dispersions, but HTST pasteurization of whey and UF retentate had no significant effect upon this latter parameter.

The functional properties, modification and utilization of whey proteins

Whey protein has an excellent nutritional value and exhibits a functional potential. In comparison with certain other food proteins, the whey protein content of essential amino acids is extremely favourable for human consumption. Depending on the heat-treatment history thereof, soluble whey proteins with utilizable functional properties, apart from high biological value, true digestibility, protein efficiency ratio and nett protein utilization, can be recovered. Various technological and chemical recovery processes have been designed. Chemically and enzymatically modified whey protein is manufactured to obtain technological and functional advantages. The important functional properties of whey proteins, namely hydration, gelation, emulsifying and foaming properties, are reviewed.

Compositional and Selected Functional Properties of Whey Protein Concentrates and Lactose-Hydrolyzed Whey Protein Concentrates

Commercial whey protein concentrate (WPC) products, manufactured by ultrafiltration with and without lactose hydrolysis, were compared for proximate composition, mineral and trace mineral composition and for protein solubility and viscosity parameters. Protein concentration ranged from 30.5 to 52.7%, while ash content ranged from 5.9 to 12.0%. Extent of lactose hydrolysis in lactose-hydrolyzed WPCs was estimated at 60 to 75% of the initial lactose level. Protein solubility of 10% protein dispersions of the WPC samples ranged from 90 to 100% and was not affected by heating WPC dispersions at 65°C for 30 min or by increased centrifugation force in solubility determination from 40,000 × g to 100,000 × g. All WPC dispersions exhibited pseudoplastic flow behavior as indicated by flow behavior indices (n) of less than 1.0. WPC dispersions possessed a low viscosity as indicated by consistency index (k) data, and k values decreased slightly after heating. Lactose hydrolysis had no apparent effect on solubility or viscosity properties of the WPC dispersions. Alteration of electrophoretic mobility of polyacrylamide gel electrophoresis was observed for α-lactalbumin in lactose-hydrolyzed WPC samples.

Effect of Processing on Whey Protein Functionality

Whey protein concentrate preparations, prepared by electrodialysis, ultrafiltration, reverse osmosis, gel filtration, and reagent complexation, are highly variable in their composition and functionality. The important functional properties of whey protein concentrates are solubility, whipping and foaming, emulsification, and gelation. Factors affecting these properties include: whey source and composition, cheese or casein manufacturing conditions, heat treatment conditions, fractionation and isolation conditions, storage conditions, overall sanitation conditions, and techniques used for functionality evaluation. Process modifications such as selective heat treatment, selective demineralization or ion exchange, and preteolytic enzyme hydrolysis may be used to alter these functional properties for a desired use application.

Effects of Various Heat Treatments on Structure and Solubility of Whey Proteins

Structure and solubility of whey proteins are interrelated and affected by commonly used heat treatments. The relation between these characteristics, however, varies with the nature of the protein and the composition of the protein solution.After a brief analysis of structure and properties of the major whey proteins in the native state, attention is given to effects of thermal treatments (up to 150°C) on structure and solubility of the different whey proteins. It is pointed out that mild heat treatments up to 60°C may affect reversibly the solubility and foaming properties of whey proteins. Conformational changes, as reflected by differential scanning calorimetry and observed above 60°C for α-lactalbumin and near 80 and 140°C for β-lactoglobulin, however, exert more serious effects on the functional properties of whey proteins. Modifications of cystine-residues in the polypeptide chain are detected by amino acid analysis upon heat treatments above 100°C under identical heating conditions as used for differential scanning calorimetry.Special attention is given to the effect of changes of environmental conditions such as pH and the presence of lactose and calcium salts, to get more information on the complicated relation between structure and properties of proteins in whey.

CONTINUOUS COAGULATION OF COTTAGE CHEESE WHEY PROTEIN

ABSTRACTProcesses are described for obtaining a low moisture, free‐flowing protein powder of high nutritional value through the high temperature (120°C) heat coagulation of cottage cheese whey protein in a constant stirred reaction vessel using steam injection heating. Dried protein concentrates produced by the suggested alternative processes contain 65%, 85% and 95% protein, respectively. Essentially all the coagulable protein can be removed in 8 min of holding time in a pH range of 5.5–6.5. Increasing coagulation temperature to above that of conventional methods (85–100°C) significantly decreases processing time without adversely affecting product quality. The highly nutritious protein fraction produced has potentially wide application in the protein fortification of foods not requiring the normal functional properties of whey protein.

Composition and Properties of Whey Protein Concentrates from Ultrafiltration

Chemical and nutrient composition and functional properties of whey protein concentrates from ultrafiltration of sweet and acid wheys were studied for potential food uses. Vitamins passed readily through the membrane; thus, vitamin content was slightly higher than in whey. Amino acid values were considerably higher, increasing in direct proportion to increases in protein. Lysine availability was not significantly affected by fractionation or by subsequent beat treatment. Since this process results in substantial removal of minerals along with the permeate, the protein to ash ratio of the protein concentrate increased. Unlike most other methods of recovering protein from whey, solubility was not adversely affected by ultrafiltration. However, protein concentrates were susceptible to heat; normal pasteurization temperatures resulted in approximately 20% denaturation. Whey protein exhibited excellent water retention. Addition of 1.5% protein to skim milk followed by heating formed a custard-like gel with sufficient body to stand alone without leakage. Approximately twice as much egg albumin was required to achieve comparable results. Whipping properties were very good when butterfat content was less than 2%. Excellent stable whips could be produced by a combination of heat and pH adjustment.

EFFECT OF ENZYMATIC HYDROLYSIS ON SOME FUNCTIONAL PROPERTIES OF WHEY PROTEIN

A study was undertaken to further elucidate the functional properties of whey protein with respect to foaming and emulsifying capacities and to observe the effect of enzymatic hydrolysis on these properties. Emulsion capacity decreased as proteolysis continued suggesting there is an optimum mean molecular size of the proteins involved which is lower than that of casein. Heat treatment of the reconstituted protein concentrate was necessary for foam stability; specific volume and foam stability increased directly with temperature of heating. Re effect of pH on whippability, data indicate that the greater the net charge the greater the tendency to foam. A limited amount of hydrolysis appears desirable to increase foaming but greatly decreases foam stability.