A Quantitative Study of the Heat Labile Sulpides of Milk. III. Influence of Ph, Added Compounds, Homogenization and Sunlight1, 2
Summary Sulfide liberation from milk is decreased either by low pH values or pH values above 9; by sugars, formaldehyde, cystine, sodium chloride, hydrogen peroxide, iodine, and the following metals: copper, silver, mercury, and iron. An increase in the heat labile sulfides results by increasing pH values between 6.5 and 9, and by the addition of ethyl alcohol, sodium sulfite and cysteine-HCl. Those factors which apparently have no effect upon the formation of sulfhydryl compounds in milk are homogenization, sunlight, and the addition of salts of nickel, tin, aluminum, and manganese. Sulfide liberation from milk may be decreased by (a) treating milk so that the denaturation and coagulation of serum proteins are retarded or prevented, (b) oxidizing or blocking out the sulfhydryl groups as they are formed, or (c) by adding materials that will combine with the liberated sulfides. Enhancement of sulfide liberation may be produced by (a) treating milk so that denaturation and coagulation of serum proteins are favored, or (b) by creating a reduced system through the addition of suitable reducing agents.