Whey protein concentrates and isolates

The consumption of dairy products plays a significant role in providing high-quality protein, vitamins, minerals, and other bioactive compounds to the American diet. Dairy products are consumed fresh in the United States in the form of fluid milk, cheese, yogurt, butter, and ice cream. Dried and condensed products such as nonfat dried milk, whey, whey protein concentrates, and isolates are also produced which are used as ingredients to boost the nutritional and functional properties of a host of other food... 

Morr, C. V. and Ha, E. Y. (1993). Whey protein concentrates and isolates Processing and functional properties. Grit. Rev. Food Sci. Nutr. 33, 431-476. 

Nalesnik, C., Onwulata, C., Tunick, M., Phillips, J., and Tomasula, P. (2007). The effects of drying on the properties of extruded whey protein concentrates and isolates. /. Food Eng. 80, 688-694. 

JN de Wit, G Klarenbeek, E Hontelez-Backx. Evaluation of functional properties of whey protein concentrate and whey protein isolates. Neth Milk Dairy J 37 37-49, 1983. 

Morr CV and Foegeding EA. Composition and functionality of commercial whey and milk protein concentrates and isolates A status report. Pood Technol. 1990 44(4) 100-112. 

Ultrafiltration processing for whey proteins concentration and fractionation, for recovery of lactose from milk and whey, for total milk protein concentration for the production of milk protein concentrate (MFC) or nulk protein isolate (MPl), for milk standardization for continuous mechanized manufacture of cheese and other fermented products, and for production of high-solids milk base for dried milk production. 

With a few exceptions, most of the detailed research has been performed on relatively few proteins. Of these, the caseins (a , B and k) and whey proteins P-lactalbumin and B-lactoglobulin) predominate. This is principally because these proteins are readily available in pure and mixed forms in relatively large amounts they are all quite strongly surfactant and are already widely used in the food industry, in the form of caseinates and whey protein concentrates or isolates. Other emulsifying proteins are less amenable to detailed study by being less readily available in pure form (e.g., the proteins and lipoproteins of egg yolk). Many other available proteins are less surface active than the milk proteins, for example, soya isolates (49), possibly because they exist as disulfide-linked oligomeric units rather than as individual molecules (50). Even more complexity is encountered on the phos-phorylated lipoproteins of egg yolk, which exist in the form of granules (51), which themselves can be the surface-active units (e.g., in mayonnaise) (52). 

FIGURE 5.6 Solubility of texturized dairy protein products extruded at different temperatures, 25 (control), 50, 75, and 100 C Nonfat dried milk (NDM) whey protein concentrate (WPC80), containing 80% protein and whey protein isolate (WPl), containing 95% protein (Onwulata et at, 2003a). 

Proteins of egg white denature more rapidly than those of whey protein concentrate (13, 34). However, isolated p-lactoglobulin from the whey concentrate was more susceptible to surface denaturation than egg white ovalbumin. These data suggest that whey contains substances that protect the proteins from surface denaturation and may account for the lower stability of whey protein concentrate foams than those of egg white protein. A balance between the disaggregation effect of select pH values and the tendency toward greater aggregation of proteins at higher heating temperatures were correlated closely with maximum foam stability (13, 15). 

One of the important developments in dairy technology in recent years has been the fractionation of milk into its principal constituents, e.g. lactose, milk fat fractions and milk protein products (caseins, caseinates, whey protein concentrates, whey protein isolates, mainly for use as functional proteins but more recently as nutraceuticals , i.e. proteins for specific physiological and/or nutritional functions, e.g. lactotransferrin, immunoglobulins). 

Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Lactose and lactose derivatives Fresh cheeses and cheese-based products Functional applications, e.g. coffee creamers, meat extenders nutritional applications Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Various fermented milk products, e.g. yoghurt, buttermilk, acidophilus milk, bioyoghurt... 

Like the caseins, the whey proteins have been isolated from whey or whey concentrates and purified by differential solubilities, electrophoresis, or chromatography. 

The three proteins chosen for this study are a mildly produced soy protein isolate, kindly provided by Central Soya, a commercially available sodium caseinate (DMV, Holland) and a whey protein concentrate (WPC) obtained by ultrafiltration (UF) and spray drying of cheese whey. Analysis of the proteins is given in (4) and (11). The present protein products have been investigated , when dispersed in distilled water and in 0.2 M NaCl solution at pH 7 denoted as (0 - 7) and (0.2 - 7), respectively. 

The interfacial and emulsifying behavior of three food proteins, a soy protein isolate, a sodium caseinate and a whey protein concentrate (WPC) have been studied. A kinetic analysis of the interfacial tension decay of the proteins indicates the following characteristics. The soy proteins diffuse slowly to the interface compared to the other proteins, probably with the quaternary structure intact, which disintegrates when adsorbed at the interface. Both the whey proteins and the caseinates diffuse quickly to the interface, where for the caseinates the diffusion--controlled occupation of the interface is very evident, especially at an ionic strength of 0.2. 

The first soybean protein ingredients made commercially available for food use included full-fat and defatted soy flours and grits (3, 7, 8). These products contain ca. 46-59% protein (NX 6.25) on a moisture-free basis and are available with various heat treatments for specific end-use. Soy protein concentrates and soy protein isolates were introduced into the market about 15 years ago (3, 9, 10, II). By definition soy protein concentrates must contain no less than 70% protein (N X 6.25) and isolates no less than 90% protein (N X 6.25), all on a moisure-free basis. In the past several years there has been much activity in the commercialization of textured soy protein products intended for the extension and replacement of meat. These textured products may be obtained through fiber spinning, shred formation, extrusion, or compaction (12, 13, 14, 15). In addition, soybean milk solids and the heterogeneous proteins in soybean whey might serve as useful substrates in chemical modifications for food use. This short recitation of commercial products illustrates the type of crude protein fractions available for practical modification. Many useful functional properties have been ascribed to these new food proteins. 

One of the current approaches to the improvement of the functional properties of proteins is enzymatic hydrolysis [148], The emulsifying ability of soy protein isolate can be increased by treatment with neutral fungal protease however, this treatment decreases emulsion stability [163], Partial hydrolysis of fish protein concentrate improves both emulsification and stability [164]. On the other hand, treatment of whey protein concentrate with pepsin, pronase, and pro-lase leads to a decrease in emulsification ability, suggesting that there... 

While foaming is favored by increased viscosity, hydrophobicity, and solubility, the increase of net charge density caused by succinylation tends to decrease foam stability (FS), since it prevents optimum protein-protein interactions required in a continuous film around air bubbles. Therefore a number of succinylated proteins showed a drop of the FS with increasing degree of modification. This was reported for protein preparations from faba beans [86], peas [72], cottonseed [69], oat [66], and cheese whey protein concentrate [88] for instance. The unfavorable charge effect of succinylation can be overcome by foaming at sufficiently high protein concentration, as shown for faba bean protein isolates [86] and napin from rapeseed [84]. 

Acid coagulation Cheese whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Lactose and lactose derivatives Fresh cheeses and cheese-based products... 

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