Use of power ultrasound to enhance the thermal inactivation of Clostridium perfringens spores in beef slurry

Clostridium perfringens is a pathogen of concern in pasteurised foods. The main objective of this study was to use power ultrasound to enhance the thermal inactivation of C perfringens spores in beef slurry. The effect of simultaneous ultrasound and heat (TS, thermosonication) on the spore inactivation in beef slurry was first investigated. At 75 degrees C, a 60 min TS process (24 kHz, 0.33 W/g) resulted in a less than 1.5 log reduction for both C. perfringens NZRM 898 and NZRM 2621 spores. Then, the thermal inactivation first order kinetic parameters of C perfringens spores in beef slurry were estimated for the two strains. The D-105 degrees C- and z-values were 2.5 min and 10.6 degrees C for NZRM 898 and 1.8 min and 10.9 degrees C for NZRM 2621. After, the effect of a spore heat shock followed by ultrasound on its thermal inactivation in beef slurry was investigated. This heat shock + ultrasound pretreatment was able to double the spore thermal inactivation rate in beef slurry. For example at 95 degrees C D-value of 202 min decreased to 9.8 min, demonstrating that spore exposure to heat shock followed by ultrasonication enhanced its thermal inactivation. (C) 2015 Elsevier B.V. All rights reserved.