Effect of Denaturing Agents on Stability of Casein, Milk, and Sterile Concentrated Milk

N-ethylmaleimide, p-chloromercuribenzoate, and dioxane revealed no differences in reactions of stability between K-casein, casein, milk, and ungelled and gelled sterile concentrated milks.However, the hydrogen and hydrophobic bondbreaking reagents urea, sodium salicylate, and lithium chloride did not change the stability of caseins and gelled concentrated milk to Ca ++ , but increased that of milk and ungelled concentrate.These differences between protein solutions might be due to increased stability of nonmicelle casein over that in micelle form.Sodium dodeeyl sulfate (SDS) increased stability of protein, due to possible destruction of micelles, then it combined with protein at higher concentrations.Decreased stability of gelled concentrated milk could not be explained by denaturing with urea and SDS.The reducing or oxidizing agents NaBH~, Na.~SO~, sodium ascorbate, mereaptoethanol, cysteine, H~O:, and K.~Fe(CN)~ affected the disulfide linkages in casein and decreased the stability of protein to Ca **.It is possible that changes in the disulfide linkages, hydrolytic cleavage of casein, or both decreased stability of protein in gelled concentrated milk.