Enhancing the Inactivation of Bacterial Spores during Pressure-Assisted Thermal Processing

Abstract

High pressure treatments have been the best pasteurization alternative to thermal processing due its capacity to reduce microbial safety risks and increase shelf life by inactivating microorganisms and key food spoilage–causing enzymes while retaining food freshness. In spite of these advantages, an important drawback limiting a wider application of this technology is its inability to inactivate bacterial spores which are resistant to several stress conditions, including high pressure. An approach to pressure-mediated spore inactivation is to promote spore germination which reduces their resistance to inactivation treatments. However, the germination response, and thus the spore inactivation rate achieved by these treatments, is strongly dependent on the food matrix, process conditions, spore physiology factors, and also on their interactions. Statistical experimental designs, such as the use of the central composite design as an optimization tool to identify effective PATP treatments as opposed to one-factor-at-a-time experimental designs, can reveal the importance of the effect of individual and combined factors on the inactivation response. A general review of these factors and examples of agents that could lower the severity of pressure treatments required to inactivate spores is here presented including the modelling of germination as affected by these factors.