Ethylene Oxide Resistance of Microorganisms Important in Spoilage of Acid and High‐Acid Foods

SUMMARY: Resistance values were determined for spores of Bacillus coagulans (var. thermoacidurans), conidiospores of Aspergillus niger, vegetative cells of Lactobacillus brevis, Leuconostoc mesenteroides, Hansenula anomala and Saccharomyces cerevisiae (var. tetrasporus) exposed to a mixture of ethylene oxide (12%)and dichlorodifluoromethane (88%). Exposures were made of organisms deposited on glass and paper discs at 33% relative humidity, 30°C and a pressure to give 700 mg per liter of ethylene oxide. Spores of B. coagulans were also exposed at 40°, 50° and 60°C. The resistance parameter D was determined to characterize the resistance of each organism displaying logarithmic death. Values of z were determined for spores of B. coagulans. The most resistant organism was B. coagulans. The spores of this organism were approximately 1.8 to 8 times more resistant than the vegetative cells of L. mesenteroides or L. brevis. Vegetative cells of H. anomala, S. cerevisiae and conidiospores of A. niger displayed nonlogarithmic death. A. niger was the most resistant of the three.