Survival Of Salmonella On Red Meat In Response To Dry Heat

Red meat is associated with Salmonella outbreaks, resulting in negative impacts for the processing industry. Little work has been reported on the use of dry heat as opposed to moist heat against Salmonella on red meat. We determined the effect of drying at 25 degrees C and dry heat at 70 degrees C with similar to 10% relative humidity for 1 h against 11 Salmonella strains of multiple serovars on beef, lamb, and goat and rubber as an inert surface. Each strain at similar to 10(8) CFU/mL was inoculated (100 mu L) onto +/- 1 g (1 cm(2)) of each surface and allowed to attach for 15 min in a microcentrifuge tube. Samples were then exposed to 70 and 25 degrees C with similar to 10% relative humidity in a beating block. Surviving Salmonella numbers on surfaces were enumerated on a thin agar layer medium. If numbers were below the limit of detection (2.01 log CFU/cm(2)), Salmonella cells were enriched before plating to determine the presence of viable cells. Water loss (percent) from meat after at 25 and 70 degrees C was determined. Whole genres of Salmonella were interrogated to identify the presence-absence of stress response genes (n -30) related to dry heat that may contribute to the survival of Salmonella. The survival of Salmonella at 25 degrees C was significantly higher across all surfaces (similar to 6.09 to 7.91 log CFU/cm(2)) than at 70 degrees C (similar to 3.66 to 6.33 log CFU/cm(2)). On rubber, numbers of Salmonella were less than the limit of detection at 70 degrees C. Water loss at 70 degrees C (similar to 17.72 to 19.89%) was significantly higher than at 25 degrees C (similar to 2.98 to 4.11%). Salmonella cells were not detected on rubber, whereas survival occurred on all red meat at 70 degrees C, suggesting its protective effect against the effect of heat. All Salmonella strains carried 30 stress response genes that likely contributed to survival. A multi-antibiotic-resistant Salmonella Typhimurium 2470 exhibited an increase in heat resistance at 70 degrees C on beef and lamb compared with other strains. Our work shows that dry heat at 70 degrees C for 1 h against Salmonella on red meat is not a practical approach for effectively reducing or eliminating them from red meat.