Recent Advances in Minimal Heat Processing of Fish: Effects on Microbiological Activity and Safety

Thermal processing is one of the most common methods for achieving safe convenience fish products with an extended shelf life. Designing a thermal process for such products, typically in the range of 60-95 A degrees C for 10 to 30 min, is challenging since the heat load required for inactivating target microorganisms may cause undesirable quality changes in the lipid and protein fraction. Concern about the safety of some fish products exists, particularly when considering the potential abuse caused by storage temperature. New methods that focus on minimal heating or rapid heating of fish products are therefore of vital importance. The main aim for new developments is to reduce the overall thermal load by reducing the temperature gradients in the product or by targeting specific potentially infected areas. In both cases, alternative technologies to conventional autoclaves, combi-steamers or water baths are used for enhanced heat transfer, thereby providing more rapid heating and avoiding unnecessarily high heat loads on part of the product. Dielectric heating, Shaka technology and surface pasteurisation are technologies that meet these approaches, and are now available for industrial applications. Minimal processing often relies on the use of multiple sub-lethal stresses or processes to achieve a similar level of microbial control such as that traditionally achieved by using a single lethal stress. Most minimally processed products require refrigerated storage and distribution to maintain food safety.