Enhancement of diffusion through foods using alternating electric fields

This work describes a procedure and equipment to study molecular diffusion in model foods under conditions of elevated temperatures and in the presence of alternating electrical fields by the uptake of indicator dyes. A series of experimental rigs have been built which allow diffusion to be studied over a range of temperatures. A technique, based on image analysis and optical microscopy, has been developed to visualise diffusion into solids on a micron scale. Diffusion between potato, alginate and agar gels and a series of dyes (rhodamine, methylene blue and fluorescein) has been quantified using this equipment; the development and accuracy of standard curves is discussed. The enhancement of diffusion is proven for rhodamine infusion into potato at 100 °C, where electric fields enhance infusion by ca. 70%. Enhancement of diffusion is also shown for diffusion of the three dyes into alginate–potato mix and agar gels.Industrial relevanceA range of effects have been shown to occur when electric fields are applied to foods. Ohmic (electrical resistance) heating has been used commercially as a way of rapidly providing volumetric heating for sterilisation or pasteurisation of foods. This paper demonstrates that similar electric field strengths significantly enhance diffusion processes between real and model foods and the surrounding liquid.