Whey amino acid composition

Recovery, Purity and Amino Acid Composition of CMP. The elution profiles of the CMP powders obtained on size exclusion chromatography 23) are shown in Figure 6. Both CMP isolated from WPC and whey did not contain major... 

Isoelectric precipitation results in loss of whey protein as well as undesirable non-protein components. Gillberg (35) has shown that the cystine composition of the isolate is lower than for the meal extract because non-precipitated whey protein has a relatively larger proportion of the total sulfur amino acids. This observation is reinforced by Mattil (36), who showed that the range for amino acid composition was different for several commercial concentrates as compared to commercial isolates. He found methionine to be lower for isolates than for concentrates. 

The caseins are often considered to be rather hydrophobic molecules. However, consideration of the amino acid composition indicates that they are not particularly so in fact, some are more hydrophilic than the whey protein, /3-lactoglobulin (Table 4.2). However, the caseins do have high... 

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.). 

A rapid FTIR method for the direct determination of the casein/whey ratio in milk has also been developed [26]. This method is unique because it does not require any physical separation of the casein and whey fractions, but rather makes use of the information contained in the whole spectrum to differentiate between these proteins. Proteins exhibit three characteristic absorption bands in the mid-infrared spectrum, designated as the amide I (1695-1600 cm-i), amide II (1560-1520 cm-i) and amide III (1300-1230 cm >) bands, and the positions of these bands are sensitive to protein secondary structure. From a structural viewpoint, caseins and whey proteins differ substantially, as the whey proteins are globular proteins whereas the caseins have little secondary structure. These structural differences make it possible to differentiate these proteins by FTIR spectroscopy. In addition to their different conformations, other differences between caseins and whey proteins, such as their differences in amino acid compositions and the presence of phosphate ester linkages in caseins but not whey proteins, are also reflected in their FTIR spectra. These spectroscopic differences are illustrated in Figure 15, which shows the so-called fingerprint region in the FTIR spectra of sodium caseinate and whey protein concentrate. Thus, FTIR spectroscopy can provide a means for quantitative determination of casein and whey proteins in the presence of each other. 

The amino acid composition of the total protein, casein, and whey protein of bovine milk is presented in Table 10.6. 

In the UK, it is recommended that infants who are not breast fed are fed modified milks until at least 6 months of age. These contain less solute, protein, sodium, calcium and phosphorus than cows milk. The Codex Alimentarius lays down international standards for infant feeds Some modified milks are based on demineralised whey and milk to reduce the protein content and change the whey casein ratio examples are given in Table 1. This provides an amino acid composition more closely resembling that of human milk but does not overcome the problem that beta-lactoglobulin and other cows milk proteins are introduced and the anti-infective factors provided by human milk are absent. 

Casein. Milk contains proteins and essential amino acids lacking in many other foods. Casein is the principal protein in the skimmed milk (nonfat) portion of milk (3—4% of the weight). After it is removed from the Hquid portion of milk, whey remains. Whey can be denatured by heat treatment of 85°C for 15 minutes. Various protein fractions are identified as a-, P-, and y-casein, and 5-lactoglobulin and blood—semm albumin, each having specific characteristics for various uses. Table 21 gives the concentration and composition of milk proteins. 

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