Whey protein functional properties

Protein-Based Substitutes. Several plant and animal-based proteins have been used in processed meat products to increase yields, reduce reformulation costs, enhance specific functional properties, and decrease fat content. Examples of these protein additives are wheat flour, wheat gluten, soy flour, soy protein concentrate, soy protein isolate, textured soy protein, cottonseed flour, oat flour, com germ meal, nonfat dry milk, caseinates, whey proteins, surimi, blood plasma, and egg proteins. Most of these protein ingredients can be included in cooked sausages with a maximum level allowed up to 3.5% of the formulation, except soy protein isolate and caseinates are restricted to 2% (44). 

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... 

TABLE 5.4 Properties of whey protein isolate as function of extrusion temperature (Onwulata et ai, 2003a)... 

Matthey, F. P. and Hanna, M. A. (1997). Physical and functional properties of twin-screw extruded whey protein concentrate-corn starch blends. LWT Food Sci. Technol. 30,359-366. 

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. 

Queguiner, C., Dumay, E., Cavalier, C., and Cheftel, J. C. (1989). Reduction of Streptococcus thermophilus in a whey protein isolate by low moisture extrusion cooking without loss of functional properties. Int. ]. Food Sci. Technol. 24, 601-612. 

The efficiencies of protein (75-80%) and starch (88-93%) recoveries by the dry process were higher than the 73-79% recoveries by wet processing, and there were no losses of solids in the whey and wash water or need for effluent recovery. The starch fraction was similar to refined starch in most functional properties except for a low amylograph viscosity. 

In vitro, the enzyme is able to catalyze crosslinking of whey proteins, soy proteins, wheat proteins, beef myosin, casein, and crude actomyosin (which is refined from mechanically deboned meat), improving functional properties such as the texture of food products [49-53], Bonds formed by transglutaminase exhibit a high resistance to proteolytic degradation [54],... 

These transglutaminase-catalysed reactions can be nsed to modify the functional properties of food proteins. Transglutaminase has been nsed to catalyze the cross-hnking of a nnmber of proteins, such as whey proteins, soy proteins, glnten, myosin and... 

Whey protein concentrates (WPC), which are relatively new forms of milk protein products available for emulsification uses, have also been studied (4,28,29). WPC products prepared by gel filtration, ultrafiltration, metaphosphate precipitation and carboxymethyl cellulose precipitation all exhibited inferior emulsification properties compared to caseinate, both in model systems and in a simulated whipped topping formulation (2. However, additional work is proceeding on this topic and it is expected that WPC will be found to be capable of providing reasonable functionality in the emulsification area, especially if proper processing conditions are followed to minimize protein denaturation during their production. Such adverse effects on the functionality of WPC are undoubtedly due to their Irreversible interaction during heating processes which impair their ability to dissociate and unfold at the emulsion interface in order to function as an emulsifier (22). 

Kuehler and Stine (43) studied the functional properties of whey protein with respect to emulsifying capacity as affected by treatment with three proteolytic enzymes. Two microbial proteases and pepsin were examined. The emulsion capacity decreased as proteolysis continued, suggesting that there is an optimum mean molecular size of the whey proteins contributing to emulsification. 

Kinsella, J.E. and Whitehead, D.M. 1989. Proteins in whey Chemical, physical, and functional properties. Adv. Food Nutr. Res. 33 342-439. 

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. 

Lactoglobulin is a major whey protein. It is present in the milk of various ruminant species (Godovac-Zimmermann et al., 1990a,b Sawyer and Holt, 1993 Ochirkhuyag et al., 1998). This protein constitutes a major waste product of the cheese industry. Only recently, its use increased as a food additive thanks to its good nutritional properties (Smithers et al., 1996). Consequently, the improvement of (3-lactoglobulin functional properties may be of considerable interest to industry. 

The whey produced during cheese and casein manufacturing contains approximately 20% of all milk proteins. It represents a rich and varied mixture of secreted proteins with wide-ranging chemical, physical and functional properties (Smithers et al., 1996). Due to their beneficial functional properties, whey proteins are used as ingredients in many industrial food products (Cheftel and Lorient, 1982). According to Kinsella and Whitehead (1989), functional properties of foods can be explained by the relation of the intrinsic properties of the proteins (amino acid composition and disposition, flexibility, net charge, molecular size, conformation, hydrophobicity, etc.), and various extrinsic factors (method of preparation and storage, temperature, pH, modification process, etc.). 

Nacka, F., Chobert, J.-M., Burova, T., Leonil, J., and Haertle, T. 1988. Induction of new physicochemical and functional properties by the glycosylation of whey proteins. J. Protein Chem. 17, 495-503. 

A whey protein hydrolysate BioZate , containing ACE-inhibitory peptide was recently developed by Davisco Foods International Inc. The effect on blood pressure was studied with 30 unmedicated, non-smoking, borderline hypertensive men and women, and daily dose was 20 g. The results indicated that there was a significant drop in both systolic and diastolic blood pressure after 1-week treatment, which persisted throughout the study of 6 weeks. The application of this product is varied and flexible. In addition to the bioactive peptides, it has functional properties such as emulsification and foaming (Klink, 2002). 

Korhonen, H., Pihlanto-Leppala, A., Rantamaki, P., and Tupasela, T. 1998b. The functional and biological properties of whey proteins prospects for the development of functional foods. Agr. Food Sci. Finland 7, 283-296. 

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