Microwave-assisted pasteurization and sterilization - commercial perspective

© 2017 Elsevier Ltd. All rights reserved. Microwave energy has inherent advantages for heat treatment of foods due to the ability to penetrate food and microwave permeable materials to volumetrically heat the contents rather than rely solely on thermal conduction. It can be applied to both flow-through heat exchange systems for pumpable foods and to prepackaged foods. However, successful commercialization of continuous microwave-assisted pasteurization and sterilization of meals and meal components has only been slowly progressing since the 1970s. The first successful development was the Multitherm hot air and microwave energy based system out of Alpha-Laval. It was subsequently abandoned commercially, but other technology manufacturers in Europe included, e.g., Officine Meccaniche Attrezzature per Ceramiche (OMAC). They sold over 200 machines in the period circa. 1980-2000, which were based on a 2.45. GHz continuous microwave sterilization process. Products such as pasta meals became common in Italy in the 1990s and in other parts of the world excluding the United States. Also in Europe, an industrial continuous in-pack meal pasteurization system by MicVac uses 2.45. GHz microwaves. This system utilizes a one-way steam valve on the food package, which releases excess energy as steam allowing rapid heating and vacuum sealing when the product cools below boiling point. Other current reported systems include a 2.45. GHz continuous pressurized microwave sterilization system manufactured by Gustosi, and 915. MHz pressured pasteurization and sterilization systems developed out of Washington State University for US Defense and commercial consortia backers. These systems are finding growing markets enabled by many factors. The development of improved heat- and oxygen-resistant packaging allows better quality preservation. The rise of meals not prepared at home and the developments of centralized institutional catering systems has greatly expanded the range of applications. Improvements in technology, such as computer controlled processing, allow dynamic control of microwave energy to minimize any overprocessing during sterilization with consequential loss of organoleptic qualities.