Microbiological Stability of Pasteurized Ham Subjected to a Secondary Treatment in Retort Pouches

A ham processing procedure consisting of pasteurizing, packaging in retort pouches, and subjecting the hams to a secondary heat treatment was evaluated as a method of increasing microbial stability. Pasteurized hams reheated at 121°C for 10 min and stored at 1±1°C or 6±1°C showed no microbial growth after 6 or 12 months of storage. The number of microorganisms in pasteurized hams not receiving the secondary heat treatment ranged from 10³/g to >10⁸/g and from 10² to >10⁸/cm² on the surface after 3 to 5 months of storage. Pasteurized hams that had been inoculated with Clostridium sporogenes spores before pasteurization followed by a secondary heat treatment at 121°C for 10 min showed a delay in the occurrence of swollen packages when stored at room temperature compared to hams not receiving the secondary heat treatment. However, the secondary heat treatment did not prevent spoilage of hams. Ham that has not been treated to eliminate spores should be refrigerated.