The microbial flora of 113 packages of sliced cooked ham was studied over a period of 11 months (samples purchased bi-weekly). When opened and analyzed, 49 packages from stores I and II revealed counts of 1,000 to 42 million per square inch of surface area. Samples from 17 of 49 packages were sour (buttermilk odor) after 3 to 7 days at 4 to 11°C. The dominant organism in the sour samples was a non-heat resistant Microbacterium.
Twenty-four samples from packages of vacuum-packed, sliced ham from store III showed counts of fewer than 248,000 per square inch; 3 samples were sour at 7 days (4 to 11°C.) Eighteen packages of sliced ham from stores I and II were stored at 4 to 11°C for 7 days before opening; counts ranged from 3.4 million to 650 million, and 8 packages were sour. Eleven of 20 packages of vacuum-packed ham stored 7 days at 4 to 11°C before opening (store III) showed counts of 1,000 to 60,000; no souring was observed in any of the 20 packages.
1Contribution No. 355, Department of Bacteriology, Kansas State University of Agriculture and Applied Science, Manhattan.