Quantification and identification of microorganisms from the surface of smear cheeses

The cell counts of surface smear bacteria found by many authors differ over several magnitudes. The influence of sampling and growth media was studied using semi-hard cheeses ripened with a defined surface starter containing Debaryomyces hansenii, Brevibacterium linens, Arthrobacter nicotianae, Cory nebacterium ammoniagenes, and Staphylococcus equorum. For sampling of surfa ce smear bacteria two methods were compared. Cutting thin slices of an area of 30-35cm(2) with subsequent homogenisation in a Stomacher gave 50% of th e surface cell counts obtained by grating off 1 cm(2) of smear with cotton wool pads. The selectivity of both methods was identical. Because of the la rger area which is analysed by the first sampling method this method provid es a more representative picture of the cell counts of the whole cheese and should therefore be used for quantification.