Study of heat-denatured whey protein removal from stainless steel surfaces in clean-in-place systems

The build-up of protein deposits over the inner surfaces of process equipment, particularly heat exchangers, is a common phenomenon in dairy factories, which hinders the normal functioning of such equipment. In this work, we have studied the washing process of stainless steel surfaces stained with heat-denatured whey protein. To do that we have used the bath-substrate-flow (BSF) device, a bench-scale apparatus that simulates clean-in-place systems. Screening tests were performed at low temperature (30 °C) to investigate the effect of the presence of protease, NaOH, ozone and surfactants on cleaning efficiency. The best results were obtained with NaOH (0.5%, w/w), proteases (1 g L^-1) and ozone (40 NL h^-1, 80 g Nm^-3). On the other hand, the use of surfactants (either anionic or nonionic) did not improve the washing efficiency significantly. Therefore, ozone and proteases can be used as environmentally friendly cleaning agents to remove protein deposits in the food industry.