Specific limited hydrolysis and phosphorylation of food proteins for improvement of functional and nutritional properties

Abstract

Limited specific hydrolysis of casein by Staphylococcus aureus V8 protease was used to produce 2% and 6.7% hydrolysates (2 and 6.7% of the peptide bonds hydrolyzed), each containing five polypeptides (by gel filtration) ranging in size from -16,000 to -1,000 daltons. The mixtures of polypeptides had substantially increased solubilities at pH 4.0-4.5, near the isoelectric point of casein. In general, the emulsifying activity index was less for the hydrolysates than for casein; the emulsion stability was higher for the 2% hydrolysate than was the emulsion from casein. Phosphorylation of zein markedly increased the water solubility of zein above and below pH 4. When the free amino acids tryptophan and/or lysine were added to zein in the presence of POC13, some amino acids were covalently bound to zein, in addition to covalent attachment of phosphate groups. Threonine did not become incorporated into zein by this method. These derivatives were much more soluble than zein above and below pH 4, the minimum solubility point. A derivative containing 0.98 mol P/mol of zein, along with 1.05% tryptophan and 0.24% lysine, had a relative growth effect on Tetrahymena thermophili of 49% that of casein, in comparison to 4.5% for unmodified zein. All the modified zeins had improved emulsifying activity indices.

Effect of Limited Hydrolysis on Traditional Soy Protein Concentrate

“…These treatments include heating, pH adjustment, hydrolysis and covalent attachment of other constituents [6]. Many authors [1,4,7,8] have studied the effect of heath treatment under different conditions on different functional properties of soy isolates.…”

Hydrolysis of Milk Protein by a Bacillus licheniformis Protease Specific for Acidic Amino Acid Residues

“…Glu-and Asp specific proteases have been used in peptide mapping studies (Schmidt, 1988). Chobert et al, (1987Chobert et al, ( , 1988) used a Glu-and Asp-specific protease (V8) from Staphylococcus aureus to enhance the solubility and emulsifying properties of casein hydrolysates. Ju et al (1995) found that limited hydrolysis by a Bacillus licheniformis protease (BLP) increased the gel strength of whey protein hydrolysates.…”

Chemical and Enzymatic Protein Modifications and Functionality Enhancement

“…Solubility in water is often enhanced by phosphorylation (Chobert, Sitohy, and Whitaker 1987), but cross-linking reduces it (Matheis et al 1983). Phosphorylation slows down digestibility, but the degree of hydrolysis of phosphorylated casein is almost the same as that of a nonphosphorylated one (Matheis et al 1983).…”