Diffusive mass transfer and protein removal in the alkaline cleaning of a jellylike whey protein fouling layer

Single steps in cleaning a fouled heat exchanger surface eventually determine the cleaning kinetic and thus the overall performance of a cleaning process. Up to date the complex mechanisms of the mutual supportive processes in cleaning are not yet fully understood. This contribution presents a stepwise approach to investigate the individual process steps starting with the diffusion of the cleaning agent NaOH into a WPI gel, studied at stationary and flow conditions. In the experiments, temperature affected both the diffusion step and the subsequent removal but to different extents. This was further specified and it was found that there is an induction time for the release of disengaged proteins, accounting for the speed of the temperature dependent degrading reactions.