Pulsed electric fields in hurdle approaches for microbial inactivation

Abstract

In the area of food preservation, heat remains the dominant microbial inactivation technique though its impact on food quality is often at odds with increased consumer demand for minimally processed products. The milder nature of minimal processing raises new safety and stability risks, and a major trend is the combination of inhibitory techniques to effectively preserve food without the extreme use of a single technique, i.e., hurdle technology. Pulsed electric field (PEF) is a "nonthermal" technology, and its ability to inactivate vegetative microbial cells when applied alone has been widely demonstrated. However, very intense PEF treatments are often necessary for sufficient microbial inactivation to ensure food safety and stability. Also at industrial scale, these intense treatments face several technical limitations; they may affect food properties and, in addition, bacterial spores and some food enzymes are resistant to PEF. As a unit operation however, PEF lends itself to be readily integrated into a hurdle preservation approach in combination with either other chemical, physical, or even emerging physicochemical hurdles. By exploiting differences between the modes of microbial inactivation, hurdle preservation allows milder individual treatments to be applied, the net effect of which should be an effectively preserved and minimally processed product. The current chapter introduces the area of hurdle preservation and goes on to explore the use of PEF in this type of preservation approach for microbial inactivation.