Destruction of Food Spoilage, Indicator and Pathogenic Organisms by Various Germicides in Solution and on a Stainless Steel Surface1

Abstract

Representative food spoilage, indicator, and pathogenic organisms were exposed to newly developed imported iodophors and widely used representative domestic germicides that included iodophors. The organisms used in these experiments included Salmonella derby, Escherichia coli, yeast of the genus Candida, Pseudomonas aeruginosa, Staphylococcus aureus. Streptococcus lactis, and spore of Bacillus licheniformis. Results of the germicide experiments showed generally similar effectiveness by iodophor and hypochlorite. Both were superior to the quaternary ammonium compounds (QAC) when used at much lower concentrations (12.5 and 25 for the halogens and 50 and 200 ppm for the QAC). The iodophors exhibited a consistently greater rate of destruction of yeast cells than the hypochlorite when low concentrations of germicide were used. A procedure to more closely simulate actual use of germicides in food and dairy industries also was employed in this study. Special polished metal strips were inoculated with organisms and exposed to an iodophor, a sodium hypochlorite, and a QAC for 15, 30, 60, and 300 sec. Again the halogen compounds were superior to the QAC in destroying the bacterial cells, especially against gram-negative species including Salmonella.