Effects of Low-Heat Treatment on Listeria Monocytogenes Reduction

This study investigates the effects of low-heat treatments on the reduction of Listeria monocytogenes in the tryptic soy broth at temperatures of 85°C and 90°C over various time intervals. At 85°C, L. monocytogenes showed an initial concentration of 7.87 log CFU/mL, with reductions of 0.65 log and 0.88 log CFU/mL after 0.5 and 1 min, respectively. A 3-min of 85℃ treatment resulted in a 1.76 log reduction, and complete inactivation occurred after 15 min of 85℃. At 90°C, reductions were 0.72, 0.93, 1.86, and 2.99 log CFU/mL after 0.5, 1, 3, and 5 min, respectively, with complete inactivation achieved after 7 min. The Weibull model was employed to analyze the low-heat treatment data, revealing D-values (1-log reduction) of 1.64 min at 85°C and 1.09 min at 90°C. The model parameters suggested a non-linear decrease in survival rates of L. monocytogenes with treatment duration. Additionally, following FDA guidelines for seafood processing, a sequential low-heat treatment (67°C for 5 min, 72°C for 1 min, 75°C for 1 min) demonstrated cumulative reductions, achieving up to 5.97 log CFU/mL when combined. These findings highlight the effectiveness of multiple heating stages over single treatments for microbial reduction and emphasize the need for further research on the factors influencing thermal resistance in different food matrices. This study provides basic data for establishing effective low-heat processing methods to ensure the safety of L. monocytogenes in various food products.