Evaluation of Selected Sanitizers to Control Bacteria in a Simulated Sweet Water Coolant System1

Abstract

Three types of sanitizers commonly used in dairy processing plants were evaluated at varying concentrations and at 25 and 4°C for their ability to control potential spoilage and pathogenic bacteria in water. Test organisms included Pseudomonas fluorescens, Staphylococcus haemolyticus, and Bacillus spp. These had been isolated from samples of sweet water coolants collected in a previous national survey in grade A dairy plants. S. haemolyticus required 10 ppm chlorine, 12.5 ppm iodine, or 10 ppm quaternary ammonium compound (QAC) to reduce the population >99% at 25°C. At 4°C, however, only 93% of the population of S. haemolyticus was reduced with the 10 ppm QAC. Concentrations of 25 ppm chlorine, 2.5 ppm iodine, or 20 ppm QAC reduced the P. fluorescens population >99% at both 25 and 4°C. The Bacillus spp. was reduced >99% at concentrations of 10 ppm chlorine at 25 and 4°C, 2.5 ppm iodine at 25°C, and 10 ppm QAC at both temperatures. At 4°C, 2.5 ppm iodine reduced the Bacillus population to only 93%. All three organisms were reduced >90% at both test temperatures with concentrations of 25 ppm chlorine, 12.5 ppm iodine, or 20 ppm QAC.