Operational considerations for hot-washing in potato crisp manufacture

As part of an overall programme aimed at reducing the acrylamide content of crisps, this paper explores the impact of hot-washing on potato slice sugar concentration during industrial scale manufacture. We investigated cold-washing as an alternative to hot-washing, hot-wash residence time and temperature to optimise sugar removal and therefore reduce the potential for high acrylamide levels after frying. Due to the variable nature of potatoes, an extensive variability study was performed to determine confidence boundaries of results. It was found that the cold-wash unit removed on average 21% of the initial sugar content. In the hot-wash the current operational residence time of 3.5 minutes at 70^oC gave a sugar reduction of 27.5%, which could be increased to 48.5% if residence time is extended to 5 minutes. Hot-wash temperatures of 40^oC - 60^oC were found to increase glucose and fructose content and therefore the potential for acrylamide formation. A “double cold-wash” was trialled and proved to be as successful as hot-washing at 70^oC for all but the highest sugar potatoes, challenging the current operational process and offering the potential for major energy savings.