The growth, survival and thermal inactivation of escherichia coli O157:H7 in a traditional South African sausage

Abstract

This study investigated the growth and survival of Escherichia coli O157:H7 inoculated into boerewors models with (B+P) and without (B−P) sulphur dioxide preservative at a low (L) and high (H) inoculum followed by storage at 0, 4 and 10°C for 10days. The pathogen’s thermal inactivation at 50, 60, 65 and 70°C was also evaluated in B+P. The B−P at both low and high inocula had significantly higher recoveries at all temperatures compared to B+P. The BL+P and BH+P had significant reductions in recoveries at 0°C, declining to below detectable limits at days 8 and 10, respectively. At 4°C, the BL+P and BH+P recoveries declined significantly at day 10. At 10°C, significant increases were observed from days 0 to day 10 in both models and at low and high inocula. At 0°C, the BL−P and BH−P treatments had significant declines in recoveries. The combination of sulphur dioxide preservative and low temperature demonstrated the best efficacy against E. coli O157:H7 survival. Thermal inactivation of E. coli O157:H7 was 60min at 60°C, 80 s at 65°C and 60s at 70°C. This study demonstrated that E. coli O157:H7 can survive in boerewors with and without preservative and is more sensitive to heat treatment at 70°C.