There is abundant information concerning the functional behavior of whey proteins in model systems. The data on functional properties reported by different researchers, however, reveal wide discrepancies in values. For example, in the case of comparable whey preparations, apparent solubilities may range from 10 to 100%; strength of gels from 0.3 to greater than 10 N, foam overruns from 250 to 1500%, and foam stabilities from 0.5 to 30 min. Many of the data are of limited value in assessing the true functional characteristics of different preparations, treatments, or processing effects. Reports to date are useful in indicating the relative behavior of different proteins; however, the data do not always predict the performance of such proteins in actual food systems. This reflects the fact that in foods, extensive interactions with other components may occur, resulting in modified behavior of the proteins. Harper, (1984) has advocated the testing of these various preparations in simulated food systems which should validly relate the behavior to performance in commercial systems. Emphasis on standardization of specific protocols, with regard to order of addition in ingredients, temperature, pH control, and amount of energy input during mixing, homogenization, emulsification, etc. deserves serious consideration. While this approach is justifiable in terms of providing valuable data to commercial users, it does not minimize the importance of examining these proteins in model systems where the physicochemical basis of each functional attribute can be described in molecular terms (Kinsella, 1987). Such information is necessary to expedite appropriate methods of processing in order to control compositional variability, extent of denatauration, and possible protein modification. In addition, rapid, reliable tests for routine quality assurance that can provide practical information concerning functional applications would be of great value. Whey protein preparations vary immensely in functional behavior and are presently relegated to limited use as functional ingredients in the food industry. This need not be the case since conventional and new technologies permit rigorous control of production protocols, e.g., careful control of heat treatments can result in the production of whey protein preparations with consistent, reliable functional properties (deWit, 1981, 1984; Harper, 1984; Morr, 1985). As the market for functional proteins continues to expand, the whey industry must seek the means to refine whey protein products; determine useful functional properties; develop standardized manufacturing protocols; demonstrate the effectiveness of whey as a functional ingredient; promote, and then market, whey on the basis of performance at competitive cost.

Proteins in whey: chemical, physical, and functional properties

Because of the growing trend toward widespread use of protein ingredients in food formulation and fabrication, an understanding of the relationships between the physical properties of proteins and their behavior in food systems is desirable. A range of milk-derived protein preparations, i.e., dry milk, milk proteins, caseins, whey proteins, and lactalbumin, are used in a range of food products for their specific functional attributes. In this paper some of the apparent relationships between the properties of the protein components and specific functional properties are discussed. Thus, the roles of milk proteins in determining some important physical characteristics (i.e. color, bulk density, sinkability, dispersibility) of milk powders and their involvement in a range of functional properties (water holding, solubility, rheological behavior, gelation, film formation, emulsification, and foaming) are reviewed. Because of the various methods and conditions used in determining functional properties and the variability in composition of preparations it is difficult to compare data and/or reconcile differences in published information. The desirability of developing standard methods is emphasized.

Milk proteins: physicochemical and functional properties

Substantial progress has been made in understanding the basic chemical and structural properties of the principal whey proteins, that is, beta-lactoglobulin (beta-Lg), alpha-lactalbumin (alpha-La), bovine serum albumin (BSA), and immunoglobulin (Ig) This knowledge has been acquired in terms of: (1) procedures for isolation, purification, and characterization of the individual whey proteins in buffer solutions; and (2) whey fractionation technologies for manufacturing whey protein concentrates (WPC) with improved chemical and functional properties in food systems This article is a critical review of selected publications related to (1) whey fractionation technology for manufacturing WPC and WPI; (2) fundamental properties of whey proteins; and (3) factors that affect protein functionality, that is, composition, protein structure, and processing

Whey protein concentrates and isolates: Processing and functional properties

Publisher Summary This chapter describes the process of the gelation of proteins Gelation is a phenomenon; therefore, its definition and that of its product, a gel, is dependent on the perspective of the observer and the technique(s) used to observe it For example, gels may be defined by their ability to immobilize a liquid, their macromolecular structure, or their textural or rheological properties The chapter reviews a variety of protein gel systems with a broad perspective stressing similarities between them, yet not without mentioning the important differences that make each unique It describes the multicomponent protein gels The rheological and optical properties of thermally irreversible gels are the outcome of two events First, a change in protein structure is needed that permits protein–protein interactions The subsequent aggregation process, which is highly influenced by the solvent environment, may produce the gel microstructure, which is responsible for the optical and rheological properties The physical integrity of a gel is maintained by counterbalancing forces of attraction and repulsion among polymer molecules and between the polymer network and the surrounding solvent

H.W. Modler

Papers

Microstructure of Yogurt Stabilized with Milk Proteins

Functional Properties of Nonfat Dairy Ingredients - A Review. Modification of Products Containing Casein

Properties of whey protein concentrate prepared by heating under acidic conditions

Functional Properties of Nonfat Dairy Ingredients — A Review. Modification of Lactose and Products Containing Whey Proteins,

Calcium as an Adjuvant for Spray-Drying Acid Whey