Studies of the Effect of Heat on Milk Dialysates

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Abstract
Dialysis experiments on raw milk demonstrated that some unrecognized substance of low molecular wt. could be removed, which contributed to the flavor of heated milk. It was discovered that the dialysate from raw milk when heated to 80[degree]-100[degree]C produced a heated milk flavor and odor, though not the typical sulfide aroma obtained from heat-coagulated proteins. The flavor and aroma of heated milk appear to be derived from 2 sources[long dash]the heat coagulable proteins and a dialysate factor. Addition of a barium salt prevented the production of a cooked aroma upon heating. Because it was not found possible to regenerate the cooked aroma precursor from the barium precipitate, it was concluded that the desired compound had been destroyed. Of fourteen other precipating agents tried, only HgCl2 at pH 8 was effective in removing the cooked flavor precursor from the dialysate. Cooked aroma was obtained by heating the eluate from the H2S regenerated precipitate after complete removal of residual H2S. Some of the properties of the partially purified cooked flavor precursor were established, significant of which are its solubility in water, lesser solubility in methyl alcohol, slight solubility in ethyl alcohol and insolubility in other solvents such as acetone, ethers and chloroform. There is no P or S present in the compound. It is unstable in aqueous alkaline solns., but somewhat stable in aqueous acid soln. It is very unstable in acid methyl alcohol soln. free from water, showing a reaction similar to that of acetone in the presence of dry HC1.

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