The effect of copper on the death rate of Salmonella typhimurium DT104:30 in food substrates acidified with organic acids

Aims: The objective of this study was to investigate the effect of copper ions on the survival of Salmonella typhimurium DT104:30 in acidified liquid food substrates. Methods and Results: The decimal reduction time (Dvalue) of Salm. typhimurium DT104:30 was determined in acidified liquid pig feed (LPF) and skimmed milk (SM) containing a range of copper concentrations (0–50 ppm). As copper concentration increased, the death rate of Salm. typhimurium DT104:30 increased. In LPF acidified with 150 mmol l−1 lactic acid the presence of 50 ppm copper resulted in a 10‐fold increase in the death rate. Conclusions: The presence of copper salts in acidic liquid food substrates significantly increases the death rate of Salm. typhimurium DT104:30. Significance and Impact of the Study: This finding could influence policy on levels of copper in pig feed.