Model experiments to establish behaviour of Yersinia enterocolitica O:9 strains in various types of fresh dry sausage

Abstract

In model experiments different kinds of raw sausages were inoculated with liquid cultures of virulent-plasmid-carrying clinical Yersinia (Y.) enterocolitica (e.) strains of the O: 9 serotype, doses being between 10(4) and 10(5) cfu g-1. The sausage samples were stored at 3-5 degrees C and 13-16 degrees C. During the first 10 d of storage the Y.e. plate count was detected with Desoxycholate-Citrate-Lactose-Sucrose Agar every day, later on in addition to it with phosphate buffer-enrichment and with enrichment according to Schiemann (1982) in intervals of several days' duration. The pH and aw values, the contents of salt and water were detected. The multitude of complexly acting factors and substances prevents obviously the proliferation of Y.e. in fresh dry sausages. Decay dynamics of Y.e. were found to be considerably affected by storage temperature. Cold storage, basically, had a conservation effect and thus delayed the dying process of model strains. Yersinia enterocolitica-contaminated fresh dry sausage may cause potential danger to consumers, because of relatively extended survival periods of the pathogen. Therefore, manufacturers are expected to observe most stringent hygienic rules of Good Manufacturing Practice.