These SEM images demonstrate that a biofilm does form on the
packaging film of vacuum-packages. It first begins with a protein layer
and then the matrix formed by the bacteria forms on top of this protein
layer. As the spoilage bacteria concentration increases, the amount of
bacteria embedded into the biofilm also increases. Not all the bacteria can be seen because they could be embedded beneath the surface.
Towards the end of shelf life, the biofilm matrix fills in with fatty
deposits and loose protein from the purge and the pork chops due to
the extensive microbial spoilage occurring. The biggest element these
SEM images demonstrate is that there is a tri-phase system occurring
inside the vacuum-package, which consists of the purge, the fresh
meat product, and the biofilm on the packaging film.