Methylation whey proteins

We chose to prepare 14C-methyl-K-casein (M-k-C) as a tracer because of the important role of K-casein in stabilizing casein micelles (8) and because K-casein is known to participate in heat-induced interactions with whey proteins, thereby influencing the heat stability of milk (9). The reductive methylation radiolabeling procedure used low concentrations of reagents (10) and resulted in M-k-C containing approximately 1 fiinol of 14C-methyl groups for every micromole of protein monomer (about 3 /xCi/mg). When tracer M-k-C was added to skim milk, and trichloroacetic acid was added to a concentration of 2%, about 1% of the radioactivity remained soluble. After clotting of the milk with excess... 

MPA. See 1-Methyl-2-piperidineethanol 3-MPA. See Methoxypropylamine 3-Mercaptopropionic acid MPC-Milk Peptide Complex CLR. See Whey protein... 

WP. See Thiophanate-methyl WPC 34, WPC 75. See Whey protein WS-3. See N-Ethyl-p-menthane-3-carboxamide WS-134P, WS-136P. See Tetrapotassium pyrophosphate WS-23. See N,2,3-Trimethyl-2-isopropylbutamide WS-380. See Sodium silicate WS-385. See Tetrapotassium pyrophosphate WSU-114. See Zinc phosphate... 

Nielsen etal. (1985). Whey protein (from skimmed milk) was mixed with amixture of methyl linolenate and linoleate in a hand mixer, the mixture was milled after spraying with water, and stored in enameled aluminum tins sealed under air. ftmol/g Upid... 

Nielsen, H.K., Loliger, J. and Hurrell, R.F. Reactions of proteins with oxidizing lipids. 1. Analytical measurements of lipid oxidation and of amino acid losses in a whey protein-methyl linolenate model system. British J. Nutr. 53, 61-73 (1985). 

In addition to their role in primary stabilization related to viscosity increase, some hydrocolloids (particularly carrageenan) are traditionally used as secondary stabilizers. Many of the primary stabilizing hydrocolloids, including locust bean gum and carboxy methyl cellulose induce precipitation of the milk proteins in the mix. This phenomenon in ice cream mix is known as wheying-off, and may be due to direct protein-polysaccharide binding and/or protein-polysaccharide incompatibility in the water phase40. The latter phenomenon may be due to decreased solvent quality due to the competition between protein and polysaccharide for solubilisation. 

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