Survival of Salmonella in Dry Food and Feed.

The survival of Salmonella Montevideo and Salmonella heidelberg in dry milk, cocoa powder, poultry feed, and meat and bone meal was studied at three water activities (aw) in the range of 0.4 to 0.75. S. montevideo was more resistant to the various dry environments than S. heidelberg . Salmonellae were enumerated immediately after inoculation, after 2 d, and after 1, 3, 7 and 14 wk. Survival was greater at aw of 0.43 and 0.52 than at 0.75 aw. Based on these findings and due to the marked differences in survival observed in the different products equilibrated at a specific aw value, it is concluded that the survival of salmonellae in a dry product cannot be predicted on the basis of the aw alone.