ABSTRACT
Milk contains two primary sources of protein: the caseins (insoluble) and whey (soluble) (Madureira et al. 2007; Marshall 2004). After processing occurs, the caseins are the proteins responsible for making curds (caseins account for 80% (w/w) of the whole protein inventory) and can easily be recovered from skim milk via isoelectric precipitation or rennet-driven coagulation, while whey remains in an aqueous environment as a by-product. The components of whey include b-lactoglobulin, a-lactalbumin, bovine serum albumin, lactoferrin, immunoglobulins, lactoperoxidase enzymes, glycomacropeptides, peptones, lactose, and minerals (Smithers 2008; Walzem et al. 2002). Whey proteins are globular molecules with a substantial content of a-helix motifs, in which the acidic/basic and hydrophobic/hydrophilic amino acids are distributed in a fairly balanced way along their polypeptide chains (Madureira et al. 2007). Table 10.1 depicts the whey protein profile, including general chemical and physicochemical properties,
10.9.2 Glycomacropeptide ......................................................................... 239 10.9.3 Osteopontin ..................................................................................... 239
10.10 Future Trends ..............................................................................................240 10.11 Conclusion ..................................................................................................240 References .............................................................................................................. 241
TA B
LE 1
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Pr ot
ei n
Pr ofi
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fC he
es e
W he
y: C
on te
nt ,P
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ar y
St ru
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e, B
as ic
P ro
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B en
efi ts
as well as their benefits. Together, whey proteins have all the essential amino acids and in higher concentrations compared to various vegetable protein sources such as soy, corn, and wheat gluten (Walzem et al. 2002). In addition to having a full spectrum of amino acids, the amino acids found in whey are efficiently absorbed and utilized, relative to free amino acid solutions (Daenzer et al. 2001). As compared to other protein sources, whey has a high concentration of branched-chain amino acids (leucine, isoleucine, and valine), as mentioned above (Marshall 2004). In addition, whey proteins are rich in the sulfur-containing amino acids cysteine and methionine. With a high concentration of these amino acids, immune function is enhanced through intracellular conversion to glutathione (GSH). All the whey proteins have at least been implicated in a variety of nutritional and physiological effects, and apart from the major whey proteins-b-lactoglobulin, a-lactalbumin, and glycomacropeptide-whey contains a number of other proteins with potent bioactivity (Table 10.2).
