Potential of microwave technology for food extruder applications

Research purpose Within food processing, there is a need for sustainable and energy-efficient processing technologies for high-quality, nutritious foods. Microwave technology as emerging, direct heating method fulfills these goals. Fast and gentle heating is combined with precise process control, and the use of green energy sources. Extrusion is a well-established, efficient, and continuous food processing method for e.g. snacks and texturates like meat alternatives. However, its energy consumption is high, and its scalability is limited. Combining the advantages of both technologies results in microwave-assisted extrusion, presenting an innovative food processing tool, offering new opportunities for scaling. Principal results This review highlights the basic principles of extrusion technology and microwave heating involving their applications fields and technical implementations within food processing. Furthermore, a novel approach of combining both processes to a microwave-assisted food extruder is presented. Challenges involving this technology are the choice of extruder wall and screw material and temperature measurement on the microwave heating section. Possible options for scale-up and food applications as well as limitations are discussed. Major conclusion This review presents insights into a novel set-up of a microwave-assisted extruder for food processing applications. Besides technological challenges like equipment material, beneficial points are process scalability, process control, and the possibility of heating high-viscosity foods. Finally, this process bears high potential towards sustainable and energy-efficient food processing.