Fouling of food processing equipment - Critical review

Fouling of processing equipment in general and food processing equipment in particular is a global issue that results in billions of dollars in clean-up and other related expenses such as loss in productivity, increased energy input, and pollution to the environment. Reports indicate that in the US alone total costs of fouling have been estimated to be $7 billion. The impact of fouling is more pronounced in the dairy industry accounting for about 80% of the total operating costs involved. Considering the extent and scope, a critical review of fouling as related to the performance of food processing equipment and mitigation strategies is presented; which includes an assessment of promising technologies. Mechanical and chemical methods have been utilized to reduce the occurrence in fouling in food processing equipment. Modification of the surface properties (roughness, wettability, charge and charge density) of processing equipment in order to reduce the surface free energy could minimize the rate of adsorption of the foulants on to the equipment surface. The process of fouling in food processing equipment has been modeled in multi-dimensions by researchers with fair amount of success in predicting the extent of fouling. The models help to predict the surface temperatures along the plate heat exchanger surface during milk pasteurization and could help in estimating the extent of fouling. A 2D dynamic model has been shown to predict the plate surface temperatures with an average prediction error of 6.2% between the predicted and measured values. Pilot plant trial experiments on the use of modified plate surfaces for pasteurization of skim milk and tomato juice respectively have shown that about 85-95% and 80-91% reduction in fouling could be obtained. Considerable energy savings could be obtained as a result of this reduction in fouling. Surface mitigation strategies thus show promise in reducing fouling in pilot-scale plate heat exchanger trial runs during processing of milk and tomato juice. Work is in progress to scale-up the pilot-scale trial runs to real-time industry-scale studies.