Effects of Sanitation Practices on Microbial Dynamics in Meat Processing Environment

This study investigated the effects of a multistage sanitation process on the microbial populations associated with conveyor belts, drains, and air within a large commercial beef processing facility. Total aerobic counts in samples from conveyor belts, drain, and air increased after a pressurized warm water wash (P < 0.05), decreased after foaming and degreasing (P < 0.05), and were not affected (P > 0.05) by application of peracetic acid (500 ppm) or quat-based (200 ppm) no-rinse sanitizers at recommended in-use concentrations with a 5-min contact time. Enterobacteriaceae and coliforms counts on conveyor belts and drains largely followed the same pattern as those of total aerobic counts. However, the Enterobacteriaceae counts in air samples were below the detection limit (1 CFU/100 L). Escherichia coli were not recovered from belts before cleaning or after sanitation, but were detected only sporadically during sanitation. In drain samples where E. coli were recovered, counts were not affected by cleaning or sanitation steps. Sequencing results revealed that the microbial composition varied by different sampling trips. Overall, Acinetobacter was predominant throughout the sanitation process in conveyor belt, drain, and air samples, with overall relative abundance of 46.06%, 51.18%, and 55.83%, respectively. Prediction models based on sequencing data indicated that the drain surface was a significant contributor to the initial microbiota on conveyor belts, but was replaced by air at the step of pressurized water washing.