Ultrasound assisted thermal inactivation of spores in foods: Pathogenic and spoilage bacteria, molds and yeasts

Background: Pasteurization aims to achieve the reduction of vegetative microorganisms and resistant spores which are of risk to public health. Power ultrasound has been identified as a potential technology for non-thermal food pasteurization. It relies on the propagation of pressure waves (frequency ranging from 20 to 100 kHz) of high intensity sound/acoustic energy (10–1000 W/cm2) inside a liquid or semisolid food, causing inactivation of pathogenic and spoilage microorganisms. This technology can also be used in simultaneous combination with temperature >80 ◦C (thermosonication, TS) to inactivate microbial spores. Scope and approach: The current knowledge on the effect of ultrasound alone (US), TS, and ultrasound followed by a thermal process (US→T) on different type of spores relevant for low- and high-acidic foods was reviewed, including the kinetic models describing their inactivation in specific foods. Key findings and conclusions: US at room temperature (without heat) has no effect on microbial spores. In terms of microbial spore inactivation efficiency, TS was the best method, followed by US→T (non-simultaneous application) and finally heat treatment without US (T). TS employing temperatures between 90 ◦C and