Evaluation of water activity (aw) as possible parameter for the preservation of dried natural casings

Abstract

Aw as possible parameter for the preservation of dried natural casings was studied by investigating the survival of Escherichia coli, Bacillus cereus and Listeria monocytogenes during the drying process of the casings. Individual dried beef casings were rehydrated and subsequently inoculated with Escherichia coli, Bacillus cereus and Listeria monocytogenes. On day 30 post inoculation, the presence of E. coli and B. cereus could no longer be confirmed, while over 4 log cfu / g casing L. monocytogenes remained. This study indicates that the drying period of 30 days at low aw levels is not sufficiently long to eliminate all bacteria present on the natural casings. Aw solely can therefore not serve as a useful parameter for the correct preservation of dried casings. It is useful to link other parameters such as microbial growth.