Contamination of flexible pouches challenged by immersion biotesting

Abstract

Immersion biotesting has long been used to challenge packages, particularly cans, for pinholes and channel leaks. Such testing for all types of plastic packaging may not be appropriate because some packages (e.g., aseptic, hot fill) are not exposed to water. As the food-packaging industry develops alternative environmental biotests there is a need to benchmark them against traditional immersion testing. The purpose of this research was to examine the threshold of critical-defect dimensions using artificially created channel leaks of 10 and 20 μm and 5- and 10-mm lengths sealed into plastic pouches which were subsequently tested by immersion at 102 and 106 CFU of motile and nonmotile Pseudomonas fragi TM849 per ml. Forty- four percent (44%) of the pouches tested became contaminated, indicating the threshold defect value is below 10 μm. Microbial ingress was significant (P