Novel non thermal processes, such as high hydrostatic pressure (HHP), pulsed electric fields (PEFs), ionizing radiation and
ultrasonication, are able to inactivate microorganisms at ambient or sublethal temperatures. Many of these processes require
very high treatment intensities, however, to achieve adequate microbial destruction in low-acid foods. Containing non thermal
processes with conventional preservation methods enhances their antimicrobial effect so that lower process intensities can be
used. Combining two or more nonthermal processes can also enhance microbial inactivation and allow the use of lower
individual treatment intensities. For conventional preservation treatments, optimal microbial control is achieved through the
hurdle concept, with synergistic effects resulting from different components of the microbial cell being targeted simultaneously.
The mechanisms of inactivation by nonthermal processes are still unclear; thus, the bases of synergistic combinations remain
speculative. This paper reviews literature on the antimicrobial efficiencies of nonthermal processes combined with conventional
and novel nonthermal technologies. Where possible, the proposed mechanisms of synergy is mentioned.
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