We discuss the Rotated Arc Mixer (RAM) for continuous mixing and heat exchange of highly viscous foods. Principal advantages of the RAM are the simplicity of construction/disassembly and the attendant large energy savings due to the absence of internal elements. The absence of internal obstructions benefits the performance of the RAM in several ways. The geometry is amenable to in-depth analysis and is easier to scale up and optimize for specific applications. The absence of internals also has the benefit of making the RAM less susceptible to clogging and fouling, which can reduce downtime and maintenance cost. The RAM exploits chaotic advection to mix and transport heat in viscously dominated (low Reynolds number) flows. Among other things the RAM can effect good in-line mixing of viscous materials with a pressure drop that is the same as that of an open pipe; moreover, the RAM has several control parameters to tune the chaotic advection, making it flexible for applications. Examples are presented from confectionary and diary processing. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.