Whey protein addition

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). 

Phosphates, which react with calcium to reduce the calcium ion activity, assist in stabilizing calcium-sensitive proteins, eg caseinate and soy proteinate, during processing. Phosphates also react with milk proteins. The extent of the reaction depends upon chain length. Casein precipitates upon addition of pyrophosphates, whereas whey proteins do not. Longer-chain polyphosphates cause the precipitation of both casein and whey proteins. These reactions are complex and not fully understood. Functions of phosphates in different types of dairy substitutes are summarized in Table 9 (see also Food additives). 

Skim milk was initially used as the aqueous phase in margarine. Where the law allows, margarines may contain caseinates, whey proteins, or soy proteins as the proteins component in the aqueous phase. The addition to margarine of 0.01—0.1 wt % sodium caseinate in place of milk has been proposed to eliminate sticking during frying. Substituting soy proteins for milk would have the same effect. 

Ye, A., Singh, H. (2000b). Influence of calcium chloride addition on the properties of emulsions stabilized by whey protein concentrate. Food Hydrocolloids, 14, 337-346. 

In a recent study by Sun et al. (2007) of 20 vol% oil-in-water emulsions stabilized by 2 wt% whey protein isolate (WPI), the influence of addition of incompatible xanthan gum (XG) was investigated at different concentrations. It was demonstrated that polysaccharide addition had no significant effect on the average droplet size (d32). But emulsion microstructure and creaming behaviour indicated that the degree of flocculation was a sensitive function of XG concentration with no XG present, there was no flocculation, for 0.02-0.15 wt% XG, there was a limited... 

In the study of Neirynck et al. (2007), the electrophoretic mobility data indicated that whey protein-stabilized emulsion droplets became gradually more negatively charged with pectin addition at pH = 5.5. This change was not only reflected in a smaller average droplet size, but also in a significant improvement in the creaming stability of the emulsions. 

In addition to the necessary protection of the contents of the emulsion droplets, effective encapsulation technology requires that the release of the active matter be controlled at a specified rate. Benichou et aL (2004) have demonstrated that a mixture of whey protein isolate (WPI) and xanthan gum can be successfully used for the controlled release of vitamin Bi entrapped within the inner aqueous phase of a multiple emulsion. The release profile, as a function of the pH of the external aqueous phase, is plotted in Figure 7.25. We can observe that the external interface appears more effectively sealed against release of the entrapped vitamin at pH = 2 than at pH = 4 or 7. It was reported that an increase in the protein-to-potysaccharide ratio reduced the release rate at pH = 3.5 (Benichou et aL, 2004). More broadly, the authors suggest that compatible blends of biopolymers (hydrocolloids and proteins) should be considered excellent amphiphilic candidates to serve as release controllers and stability7 enhancers in future formulations of double emulsions. So perhaps mixed compatible biopolymers wall at last allow researchers to... 

Gancz, K., Alexander, M., Corredig, M. (2006). In situ study of flocculation of whey protein-stabilized emulsions caused by addition of high-methoxy 1 pectin. Food Hydro-colloids, 20, 293-298. 

Figure 3. Response surface contour plots (15) for cysteine (x,) and CaCh (Xi) addition to 10% whey protein dispersions at pH 7.0 on hardness (y,), cohesiveness (yi), springiness (ys), and compressible water (yj of gels prepared by heating at 100°C for 15 min...

Milk protein products. As indicated in Table 1, the food industry is placing major emphasis on the production and utilization of milk protein products in a wide variety of formulated food products (20,21,22). Although nonfat dry milk (NFDM) and whey powder are major milk protein ingredients in formulated foods, casein and whey protein concentrates, which contain their proteins in a more highly concentrated and functional form, are essential for certain food product applications, such as those products that require the proteins as an emulsifier agent. Additional details on the processing methods and conditions used to produce the various milk protein products are available (23). 

Lactalbumin is an insoluble whey protein product produced by heating whey to high temperatures ( > 90 C) to denature and render the proteins insoluble when adjusted to isoelectric conditions by the addition of acid. These proteins offer little functionality in emulsification applications. 

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). 

Casein is low in sulphur (0.8%) while the whey proteins are relatively rich (1.7%). Differences in sulphur content become more apparent if one considers the levels of individual sulphur-containing amino acids. The sulphur of casein is present mainly in methionine, with low concentrations of cysteine and cystine in fact the principal caseins contain only methionine. The whey proteins contain significant amounts of both cysteine and cystine in addition to methionine and these amino acids are responsible, in part, for many of the changes which occur in milk on heating, e.g. cooked flavour, increased rennet coagulation time (due to interaction between /Mactoglobulin and K-casein) and improved heat stability of milk pre-heated prior to sterilization. 

In addition to the caseins and whey proteins, milk contains two other... 

Addition of CaCl2 to about 0.2 M causes aggregation of the casein such that it can be readily removed by low-speed centrifugation. If calcium is added at 90°C, the casein forms coarse aggregates which precipitate readily. This principle is used in the commercial production of some casein co-precipitates in which the whey proteins, denatured on heating milk at 90°C for 10 min, co-precipitate with the casein. Such products have a very high ash content. 

Casein can be precipitated from solution by any of several salts. Addition of (NH4)2S04 to milk to a concentration of 260 g 1 1 causes complete precipitation of the casein together with some whey proteins (immunoglobulins, Ig). MgS04 may also be used. Saturation of milk with NaCl at 37°C precipitates the casein and Igs while the major whey proteins remain soluble, provided they are undenatured. This characteristic is the basis of a commercial test used for the heat classification of milk powders which contain variable levels of denatured whey proteins. 

In addition to simplifying and standardizing the nomenclature of the milk proteins, the characteristics of the various caseins and whey proteins are summarized in the above articles, which are very valuable references. 

In addition to the general decrease in viscosity with increasing temperature, heating milk can also influence its rheology by heat-induced denatura-tion of cryoglobulins and/or other whey proteins. Concentration of milk, e.g. by ultrafiltration, prior to heating results in a greater increase in f/app than in milk heated before concentration. 

Instantized milk powder normally exhibits low bulk density but higher water dispersibility than conventionally spray-dried powder. However, the extra heat exposure from the agglomeration and redrying treatments causes additional Maillard reaction, whey protein denaturation, and related chemical and physicochemical reactions that tend to lower product quality. 

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