Biotest with Penicillium canescens for determining integrity of flexible plastic pouches

Leaker spoilage and postprocess reinfection are terms used to describe spoilage of a food package following adequate sterilization. Since the major cause of leakage in flexible plastic pouches is through defective seals, channel leak defects of 10, 30 and 50 {dollar}mu{dollar}m in diameter were deliberately introduced in the seal area of pouches aseptically filled with culture media. It has been documented that most food spoilage problems due to filamentous fungi occur under aerobic conditions, or at least where oxygen tension is appreciable due to leakage or diffusion through packaging; but it has not been reported if fungi can pass through channel leak defects with these diameters. For this reason, these pouches were contaminated with Penicillium canescens using the immersed biotest procedure. To determine if contamination occurred, and the rates in which these defects allow contamination, the contents of the pouches were analyzed for the presence of fungi. There was a significant difference (P {dollar}{dollar}.05) between the trials or between the contamination rate for the pouches with no defect and the contamination rate for the pouches with 10 {dollar}mu{dollar}m diameter defect. The three defect sizes were detected by the elastic optical scattering technique. Infrared thermography was unable to detect the 10 {dollar}mu{dollar}m diameter defect. (Abstract shortened by UMI.)...