ABSTRACT
Both intrinsic and extrinsic factors affect the functional properties of protein. This chapter emphasizes the role of hydrophobic interactions in protein functionality and their alteration through various modification techniques and processes. Acylation of amino acid residues, particularly lysine residues, has probably been the most cohemical derivatization used in food protein applications. Phosphoproteins occurring naturally in food systems include milk caseins, egg white ovalbumin, and egg yolk phosvitin. These phosphoproteins are formed in vivo by phosphorylation of the protein precursors via a reaction catalyzed by the enzyme phosphoprotein kinase. Reaction of sulfonates and sulfonyl chlorides with proteins can be used to introduce hydrophobic alkyl and aryl sulfonyl moieties. Physical treatments include the use of thermal energy, mechanical energy, or pressure to modify food proteins. Sonication has been a widely used physical process for solubilizing animal and plant tissue components by virtue of a cavitation effect.
