Development and use of a novel method for measuring the force required to disrupt and remove fouling deposit

In studies of cleaning, the force required to disrupt the deposit and remove it from the surface tends to be inferred from flow data, and is not known directly. A micromanipulation technique has been developed to measure directly the adhesive strength of food fouling deposits on a stainless steel surface. A T-shaped stainless steel probe was specially designed to pull fouling deposits away from a stainless steel surface to which they were attached. The apparent adhesive strength between the fouling deposits and the substrate was defined as the work required to remove the deposits per unit area from the substrate. Development of the technique has used tomato paste as a model foulant. Paste was baked onto stainless steel, and the effect of baking time, hydration time before cleaning and cleaning temperature studied. Measured values of the apparent adhesive strength fall between 1 and 20 J m(-2). Strength increased with baking time and thickness of sample, and decreased with increasing hydration time and temperature. Surface roughness enhanced adhesive strength. For this deposit, the cohesive strength was greater than adhesive strength at room temperature. The results were used to explain the way in which samples were cleaned by a fluid flow.