Compounds producing the kreis color reaction with particular reference to oxidized milk fat

Abstract

Summary Evidence is presented which suggests that epihydrin aldehyde and its derivatives are not necessarily solely responsible for the Kreis color reaction of oxidized fats. Malonic dialdehyde has been shown to give a positive reaction in the Kreis test and the resulting color demonstrated to be spectrally similar to the Kreis colors obtained with epihydrin aldehyde diethyl acetal, acrolein treated with H 2 O 2 rancid lard, and oxidized milk fat. Characteristics of a water‐soluble, low molecular weight, Kreis positive, carbonyl compound from oxidized milk fat were observed to be very similar to those reported for malonic dialdehyde, i.e., strongly acidic, enolic as indicated by the ferric chloride test, and relatively stable to heating with dilute mineral acids. These properties would not be expected of epihydrin aldehyde. Three highly sensitive colorimetric reactions, involving reactions with ferric chloride, 2‐thiobarbituric acid or the Kreis reagents, might well serve as the basis for quantitative measurement of malonic dialdehyde.