The microflora of Tilsit cheese. Part 1. Variability of the smear flora

Abstract

Abstract The microflora of 25 Tilsit cheeses from 2 cheese plants was analysed. Debaryomyces hansenii was found to be the predominant yeast in all stages of ripening. 75–95% of the bacterial flora consisted of coryneform bacteria. Several of the isolates were identified as Arthrobacter. Brevibacterium linens was found at 0‐15%. In all cheeses tested, 5‐15% of total cell counts were made up by staphylococci. They were determined as being not Staphylococcus aureus or other pathogenic staphylococci since all isolates were negative with respect to thermo‐nuclease, clumping, coagulase, and hemagglutination. Most of the isolates were hemolysis negative. By genetical analysis, several selected isolates were classified as Staphylococcus equorum , one isolate as S. sciuri. Contamination of cheeses with Fusarium moulds indicated the influence of the smearing strategy on spreading of undesirable microorganisms. In plant A, old cheeses were smeared first, then young cheeses were smeared with the same smear liquid. Fusarium contamination could be detected in all stages of ripening. In plant B, young cheeses (0‐3 weeks) were smeared with a commercial surface starter cocktail. In all cheeses of this age, problems with Penicillium contaminations were observed. Older cheeses (>3 weeks) were smeared according to the strategy applied in plant A. Consequently, Fusarium moulds were detected in cheeses 4‐8 weeks of age.