SUMMARY The growth of salmonellae was observed to occur at pH values as low as 4.05 × 0.05. The growth‐limiting pH was dependent on several factors, most important the acid molecule itself. Additionally, the effect of temperature, relative oxygen supply and level of inoculum was studied. The salmonellae could not be “trained” to grow at a lower pH by sequential transfer at nearoptimum pH values.

The behavior of salmonellae during the manufacture and storage of Thuringer sausage was studied. Five serotypes of salmonellae behaved in a similar fashion during the fermentation period regardless of whether a Pediococcus sp. or Lactobacillus sp. starter culture was used. The number of salmonellae per gram of sausage emulsion decreased by 0.75 – 2.5 logs during the 18–24 hr of fermentation. Initial experiments indicated that a combination of the acidity that developed and the NaCl present was responsible for the demise of the salmonellae. Sodium nitrite, sodium nitrate, and ascorbic acid had little or no effect on the fate of salmonellae in the fermenting material. When the level of sucrose in the curing salt mixture was reduced to 0.25%, a product with a final pH of 5.2–5.4 resulted. Salmonellae were able to multiply in this sausage emulsion during the course of fermentation. Heat treatments employing three temperatures (46, 49, 52 C) were evaluated as to their efficiency in destroying salmonellae in Thuringer sausage. The effect of these heat treatments on both ‘normal’ and ‘low acid’ sausage was examined. As expected, the highest temperature was most effective in both instances. Salmonellae were able to multiply in the low acid product while it was being heated at 46 C. The number of viable salmonellae in finished Thuringer sausage declined during refrigerated storage of the product. The rate of decline was not sufficient to ensure complete destruction of even low levels of contamination.

Salmonellae inoculated onto the surface of bologna and liver cheese survived protracted storage at 5 C. Salmonellae grew when the meats were incubated at room temperature.

Salmonellae inoculated onto the surface of bologna and liver cheese survived protracted storage at 5 C. Salmonellae grew when the meats were incubated at room temperature.

No abstract