High pressure processing (HPP) at refrigeration, ambient or moderate heating temperature can inactivate pathogenic and spoilage microorganisms with fewer changes to product "freshness" as compared to conventional food preservation processes. The essential equipment components are here described to help define low and higher cost applications. Specific opportunities are discussed that a food processor can consider to profit from the significant equipment investment required to implement this new processing technology. Although, HPP is the only alternative processing technology that has reached consumers with a variety of new products, there are many pending research questions to be answered to make it a reliable alternative and to have a fundamental understanding of the inactivation of microorganisms and enzymes by pressure. Approaches to generate the knowledge required and the information that is being generated is critically reviewed. (C) 2004 Elsevier Ltd. All rights reserved.