Conical twin-screw extrusion is an effective inactivation process for Salmonella in low-moisture foods at temperatures above 65 °C

Single-screw extrusion is an effective tool in reducing microbial contamination, however, limited data exists on the efficacy of twin-screw extrusion for microbial inactivation. The purpose of this study was to evaluate the effect of fat (5–15%), moisture content (14–26%), temperature (55–85 °C), and screw speed (75–225 rpm) on Salmonella inactivation during the twin-screw extrusion of oat flour. Results indicated that Salmonella population was below the detection limit (65 °C. However, at 55 °C, Salmonella reduction ranged from 0.0 to 9.0 log CFU/g. Therefore, this data (55 °C) was used to develop the response surface equation. Fat content and screw speed showed a significant negative linear effect on Salmonella reduction, whereas, moisture content showed a significant linear and quadratic effect. As the industrial extrusion is commonly performed at temperatures >65 °C, twin-screw extrusion can be used as an effective process intervention step, after validation. The developed model can serve as a baseline for the industry to validate their extrusion process for food safety. •Salmonella was below detection limit (65 °C.•At 55 °C, Salmonella reduction varied with fat, screw speed, and moisture content.•Twin-screw extrusion is more effective than single-screw extrusion.•The developed model can serve as a baseline for planning an extrusion validation study.