Target selection in designingpasteurization processes for shelf-stable high-acid fruit products

This study is focused on the search for targets and criteria for the design of pasteurization processes for high-acid shelfstablefruit products, such as juices, nectars, pastes, purees, concentrates, jams, jellies, etc. First, an overview of pasteurization is presented and then, frequently used targets for pasteurization processes are reviewed. Enzymes naturally present in fruits, in decreasing order of heat resistance, were pectinesterase, peroxidase, and polyphenoloxidase, and they may be used as pasteurization targets. The heat resistance of each enzyme is strongly dependent on its fruit origin. The most heat resistant micro-organisms capable of spoiling high acid fruit products include ascospores of Neosartorya fischeri, Byssochlamys nivea, Talaromyces flavus, Eupenicillium javanicum, and Byssochlamys fulva moulds, as well as bacterial spores of Clostridium butyricum, Bacillus coagulans, and Bacillus megaterium. These micro-organisms, spores, and enzymes were, in general, less heat resistant than the spores of a particular spoilage micro-organism named Alicyclobacillus acidoterrestris, which has been causing problems in the fruit industry. Therefore, the use of Alicyclobacillus acidoterrestris spores as a reference micro-organism in the design of pasteurization processes for high-acid shelf-stable fruit products is suggested.