Safety of Shelf-Stable Canned Cured Meats

Shelf-stable canned cured meats (SSCCM) are preserved by thermodestruction of the vegetative microflora, partial destruction of the microbial spores, and subsequent inhibition of the surviving spores. Inhibition depends primarily on the concentration of salt, nitrite input and the severity of the thermoprocess. On the basis of published experimental work, the botulism risk of SSCCM may be estimated, either as the equivalent of the decimal heat destruction of spores, taking into account the combined destruction and inhibition in SSCCM (log 1/P), or as the decimal number of cans needed for a single can to become toxic, i.e., log 1/(P × i), where P is the probability of individual spores developing and producing toxin in the processed can, and i is the incidence of Clostridium botulinum spores in the raw product. The experimental data demonstrate that the 12 D concept (or its equivalent) is not applicable to SSCCM and cast doubt on the adequacy of the F₀ value as a measure of the effective heat treatment for this type of product. Research data on the safety of SSCCM are limited and do not allow us at present to propose minimal requirements of the essential safety factors. Instead, our risk assessment relies heavily on commercial practice and experience. In analogy to log 1/(P × i), the safety of commercial cans is expressed as the decimal number of cans produced per can causing severe illness, arbitrarily designated SU (safety units). Estimated SU values for defined commercial luncheon meats, canned cured ham and sausages, range from > 7 to > 9. Provided that the microbial spore levels of both the raw meat and non-meat ingredients of SSCCM are rigidly controlled, the SU estimates allow us to specify minimum safety requirements for the major groups of shelf-stable canned cured meats.