The effect of electrical processing on mass transfer in beetroot and model gels

The diffusion between solids and surrounding liquids has been studied under the influence of different electric field strengths varying between 0–1000 V m−1, characteristic both of ohmic heating and Moderate Electric Field (MEF) processing. The rate of enhancement of mass transfer between slabs of beetroot and surrounding fluid has been studied at up to 60 °C, as a function of electric field strength and the orientation of the slab to the field. Enhancements in diffusion coefficient of up to a factor of 2 are seen, with decreased enhancement at higher temperature and when the electric field does not pass through the particle. Diffusion into gels has been studied and enhancement found only for alginate (an ionically set gel) and not for gelatin and egg albumin, that are thermally set gels.

► The effect of MEF on mass transfer in beetroot and gels has been studied. ► MEF enhances mass transfer of betanin dye from beetroot. ► Betanin thermal degradation is significant above 60 °C. ► The effect of electric field decreases with increasing temperature. ► Particle position can be adjusted to minimize mass transfer effects.