Liquid ‘hold-up’ on stainless steel surfaces: II — Effect of surfactant concentration

The effect of surfactant concentration on the ‘hold-up’ of a representative food liquid (sucrose solution) on various stainless steel surfaces was studied.Surface finish was found to have a significant effect on ‘hold-up’, but no correlation was found between Ra value and ‘hold-up’.Although surfactant concentration was found not to be a significant independent variable it did have a significant interaction with surface finish, the differences in ‘hold-up’ between the surface finishes being reduced by an increase in surfactant concentration.Differing surfactant concentrations in food soils is proposed as a possible explanation of the conflicting reports in the literature on the cleanability of stainless steel.An explanation of the effects of surface finish and surfactant concentration on ‘hold-up’ is proposed in terms of the effects on wetting and contact angle of surfactant and the nature of the surface.