INHIBITION OF BACTERIA BY SOME VOLATILE AND NON-VOLATILE COMPOUNDS ASSOCIATED WITH MILK

Abstract

APT broth inoculated with Leuconostoc citrovorum was dispensed into aerosol cans with an epoxy lining. Twenty-five volatile or non-volatile compounds were then added individually to the cans to yield final concentrations of 1, 10, 100, and 1000 ppm of each compound. Compounds tested included fatty acids (formic, acetic, butyric, hexanoic, octanoic, and decanoic), aldehydes (formaldehyde, acetaldehyde, propionaldehyde, and glyoxal), ketones (acetone, 2-butanone, and diacetyl), amines (propyl- and hexylamine), alcohols (furfurol, and methanol), sulfur compounds (methylsulfide, methylsulfone, methanethiol, and ethanethiol), acetonitrile, chloroform, ether, and ethylenedichloride. Bacteria were enumerated at intervals and all incubations were at 30 C.Of the fatty acids tested, decanoic acid was most and butyric acid was least inhibitory to L. citrovorum. Formaldehyde was more inhibitory than glyoxal, acetaldehyde, or propionaldehyde. Diacetyl was more inhibitory than acetone or 2-butanone. Acetonitrile, chloroform, and ether, each at 100 ppm, were generally significantly inhibitory especially late in the incubation. Ethylenedichloride and methylsulfone, both at 10 ppm, also generally significantly inhibited L. citrovorum except early in the incubation. Ethanethiol was usually more effective than methanethiol, which in turn was more detrimental than methylsulfide. Amines were more inhibitory than alcohols, and even at 10 ppm were generally significantly inhibitory. Methanol was more active against L. citrovorum than was furfurol.