Aims: To determine the prevalence and number of Salmonella and Campylobacter in sausages and to evaluate their destruction during cooking.
Methods and results: One hundred and sixty-two packs of uncooked economy or catering sausages, comprising 53 packs of frozen and 109 of chilled sausages, were purchased in Devon between March and July 2000. All were tested for the presence of Salmonella and 51 packs of chilled sausages were also examined for the presence of Campylobacter spp. To investigate the heat tolerance of Salmonella enterica serovar Typhimurium DT104 in sausage-meat, chilled, handmade and frozen sausages were inoculated with approx. 1.5 x 10(4) bacterial cells per sausage (approximately 300 cfu g(-1)) and then cooked by frying, grilling or barbecuing. The levels of creatinine kinase, lactate dehydrogenase and alkaline phosphatase in uncooked and cooked sausages were measured to evaluate their potential as indicators of adequate cooking and, therefore, pathogen elimination. Salmonella were detected in 7.5% of frozen and 9.1% of the chilled sausages (8.6% overall) but Campylobacter spp. were not isolated. After cooking, a visual assessment suggested that all of the sausages were thoroughly cooked. Despite this, barbecuing and frying sometimes allowed Salmonella cells to survive and the temperature profiles during cooking indicated that the lethal range was sometimes not reached. The enzyme levels tested were not reliable indicators of the inactivation of bacterial pathogens because Salmonella were sometimes isolated from sausages with low values of all three enzymes.
Conclusions: Salmonella spp. are present in a significant proportion of sausages and are not always killed during the cooking process.
Significance and impact of the study: These findings have clear implications for public health.