Farm, Plant Measures Guard Against Salmonella

Food safety programs (Pork Quality Assurance-Plus) at the farm and at the packing plant (Hazard Analysis Critical Control Point) are effectively reducing salmonella levels in the food chain.

A literature review funded by Pork Checkoff looked at the introduction and amplification of salmonella in the harvest process to the cooler.

The results are based on 15 publications which described 40 studies that evaluated the presence of salmonella on pork carcasses during processing.

The review concluded that there is little evidence that salmonella is introduced into the pork product as it moves along the processing chain to the cooler.

The carcass sampling points evaluated were after bleeding, after stunning, after scalding, after dehairing, after singeing, after polishing, after evisceration, after washing and after chilling. The studies evaluated salmonella prevalence as the carcass moved from sampling points along the processing line.

There were 48 unique comparisons of salmonella prevalence between points on the processing line in the 40 studies. In 40 comparisons, there was either no change or a decrease in salmonella prevalence on the carcass. Of the eight cases where salmonella prevalence increased as the carcasses moved closer to the cooler, only four times was the increase more than 10%.

Overall, the median prevalence of salmonella-positive carcasses evaluated in the cooler was 0%, and the mean was 4%. This compares to the median prevalence of salmonella evaluated at bleeding of 37% and the mean of 58%, suggesting that in general, the processing procedures in place resulted in decreased carcass contamination as the carcass moved toward the cooler.

Researcher: Annette O’Connor, DVM, Iowa State University. Contact O’Connor by phone (515) 294-5012, fax (515) 294-1072 or e-mail