Inactivation of microorganisms by high isostatic pressure processing in complex matrices: A review

The benefits of high pressure processing (HPP) for microbial inactivation in food production include reduced thermal treatment and minimized effects on sensory and nutritional profiles. These benefits have resulted in increasing commercial production of high pressure pasteurized foods. In this review, the current state of the art in terms of vegetative cell and bacterial spore inactivation by HPP in complex food matrices is assessed with an emphasis on mechanisms of inactivation and treatment of products that have low or non-uniform water activity (a(w)) profiles. Low a(w) can be the result of a high concentration in solutes, the presence of oils/fats, or the physical removal of water through dehydration. Microbial inactivation in low a(w) environments remains a particular challenge for HPP and studies on microbial inactivation observed in the different types of low a(w) food matrices are reviewed in detail. Industrial relevance: HPP-treated food products with low a(w) have been on the market since the nineties, but the mechanisms of microbial inactivation at low a(w) are still not well understood, which hinders the development of new applications in low or inhomogeneous a(w) food. This review summarizes the state of the art in terms of HPP microbial inactivation mechanisms in model systems and various low a(w) food environments. Thereby, it identifies existing and potential new applications as well as the current gaps and future research needs. (C) 2014 Elsevier Ltd. All rights reserved.