Salmonella is the bacteria most commonly linked to feed and dry food contamination, and it is the source of numerous foodborne outbreaks. Conditioning and retention systems are implemented in most feed mills to optimize the pelleting process as well as serve as a kill step to minimize the microbial load of the feed grain. A study was conducted to investigate the inactivation kinetics of Salmonella spp. in broiler feed treated with superheated steam on laboratory scale since knowledge regarding the efficacy of this kill-step at varied process parameters in specific feed matrices is sparse. A literature analysis was used to identify Salmonella strains often linked with feed ingredients. After screening five Salmonella strains for heat resistance, Salmonella Agona was chosen as one of the most heat-resistant serotypes. After screening three strains of this serotype, S. Agona RA1052 (isolated from animal feed) was chosen as the best suited strain for determining Dand z-values in broiler feed at various moisture levels and temperatures. The D-values for S. Agona strain RA1052 in broiler feed mash adjusted to 12% moisture were 178.2 s and 3.1 s, respectively, were measured in a modified autoclave at 65°C and 85°C. D-values with 19 percent moisture were 81.1 seconds at 65°C and 0.7 seconds at 85°C. The surrogate Enterococcus faecium ATCC 8459 (NRRL B-2354) with an equal heat resistance to S. Agona RA1052 was used for on-site challenge experiments. The information gathered will be used to validate conditioning and retention as a Salmonella spp. kill step in pilot and industrial scale studies.
