Action of Microorganisms on the Peroxides and Carbonyls of Rancid Fat

Abstract

SUMMARY— The effects of 26 species of bacteria, molds, and yeasts on the hydroperoxides and monocarbonyls in rancid fat have been determined. All of the cultures were capable of decomposing the hydroperoxides. The activity of microorganisms on the monocarbonyl content of the rancid fat was quite varied and could be divided into: 1) microorganisms which produced large increases in at least two monocarbonyl classes; 2) microorganisms which removed 2,4‐dienals; 3) microorganisms which removed 2,4‐dienals and 2‐enals, and 4) microorganisms which caused decreases in at least two classes of monocarbonyb (without destroying completely any class). Two microorganisms produced methyl ketones, a monocarbonyl class which does not appear in rancid lard. There appeared to be a relationship between the ability to decompose peroxides strongly and the ability to produce a great increase in the monocarbonyl content. There apparently is no relationship between the ability to decompose peroxides and lipolytic activity. The possible importance of microorganisms in controlling hydroperoxides and monocarbonyls in fats is discussed.