Bioaerosol Exposure Method for Package Integrity Testing †.

Test organism motility, concentration, aerosol exposure time, hole diameter and length were evaluated to determine their influence on microbial ingress into a flexible plastic pouch. Microtubes with 10- and 20-µm hole diameters and of 5- and 10-mm lengths were used as defects in 128 flexible pouches. A bioaerosol with a 2.68-µm mean particle size comprised of 102 or 106 CFU/ml source concentrations of motile or nonmotile Pseudomonas fragi TM 849 was introduced into a 119,911-cm3 chamber for exposures of 15 or 30 minutes. Six pouches showed test organism growth after a 72-h incubation period. Microbial ingress was significant (P < .05) for motile test organisms with source concentrations of 106 CFU/ml.

Contamination of Flexible Pouches Challenged by Immersion Biotesting †.

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 artifically 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 < .05) for motile test organisms with a concentration of 106 CFU/ml. The interaction of concentration and time was also significant at 102 CFU/ml at 30 min exposure and 106 CFU/ml at 15 min. Channel length was not statistically significant. The markedly greater contamination rate using immersion testing versus that of aerosol testing highlights the importance of using test methods that reflect environmental exposure conditions of the packages.