PENETRATION OF BACTERIA THROUGH MICROHOLES IN SEMIRIGID ASEPTIC AND RETORT PACKAGES

The penetration of vegetative cells of Enterobacter aerogenes, Bacillu s subtilis, Micrococcus varians, and Leuconostoc mesenteroides through laser-drilled holes of diameter 10 to 20 mu m in the lid of commercia lly manufactured semirigid aseptic cups filled with milli chocolate pu dding and retort trays filled with spaghetti in meat sauce (only E. ae rogenes) was studied. The ability of bacteria to pass via leakages was determined using an immersion biotest method. The threshold leakage d iameter determined for both products tested was about 10 mu m. The con tamination rate of leaking packages was much higher for aseptic cups t han retort trays. The results indicated that the factors increasing th e rate of bacterial penetration into test packages are large hole size , small hole length, small bacteria diameter and leakage channels fill ed with liquid instead of dried foodstuff and/or bacterial suspension. The results an useful as a guideline for the requirements of on-line, nondestructive, package-integrity testers for testing packages.