Factors controlling the growth of Clostridium botulinum types A and B in pasteurized cured meats IV. The effect of pig breed, cut and batch of pork

Pork slurries were prepared from leg or shoulder muscle from three animals from each of three breeds of pig (Pietrain, Gloucester Old Spot and Large White × Landrace cross). Slurries (pork:water, 1:1.5) contained NaNO₂ (100 μ/g), NaCl (2.5, 3.5 or 4.5% w/v on the water), were subjected to one of three heat treatments (unheated, 80°C for 7 min, 80°C for 7 min plus 70°C for 1 hr) and stored at 35, 20, 17.5 or 15°C for up to 6 months to determine the relative effects of the above factors on growth (spoilage) and toxin production by Clostridium botulinum types A and B at 10³ spores per bottle.
Increasing salt or heat treatment, or decreasing storage temperature or inoculum level all reduced spoilage and toxin production. Both 'animal' and 'cut' significantly affected spoilage and toxin production. More spoilage and toxin production occurred in meat from the shoulder cut than from the leg cut. In both cases there was considerable variation between animals within breed, but there was no systematic difference between breeds. There is no obvious explanation for the variation in meat between animals, but it should be borne in mind when planning and assessing results of large multifactor experiments. Although there was more spoilage and toxin production after 6 months' than 3 months' storage, the statistical analyses yielded essentially similar conclusions.