Aseptic processing of liquid and particulate foods

Aseptic processing involves sterilization of a food product (in a direct or indirect contact heat exchanger), followed by holding it for a speci ed period of time (in a holding tube), cooling it, and nally packaging it in a sterile container. The use of high temperature for a short period of time (in comparison with conventional canning) in aseptic processing yields a high quality product. The demand for high quality shelf-stable products has been the driving force for commercialization of aseptic processing. Deaeration (prior to sterilization) is usually an integral part of aseptic processing as removal of air enhances product quality and increases the shelf-life of a product. It also stabilizes the product prior to processing. Care should be taken to ensure that all process calculations are performed after the deaeration stage and not based on the initial raw product. Another important part of an aseptic processing system is the back pressure valve which provides suf cient pressure to prevent boiling of the product at processing temperatures which can be as high as 125-130°C. An aseptic surge tank provides the means for product to be continuously processed even if the packaging system is not operational due to any malfunction. It can also be used to package the sterilized product while the processing section is being resterilized.