Cleaning maps: a multi length-scale strategy to approach the cleaning of complex food deposits

The removal of fat/starch deposit from stainless steel surfaces was investigated analysing the influence of several factors such as fat/starch proportion (0–100%), pH (3–13.2), temperature (40–50 °C), time (10–20min), surfactant (1 g/L linear alkylbenzenesulfonate) and α-amylase and lipase (0.2 g/L). To evaluate cleaning effectiveness, both a micromanipulation technique which measures cohesion and adhesion forces of deposits upon specific substrates and a device which simulates an industrial Cleaning-in-Place system, were used. “Cleaning maps” were used to visualise detergency, finding that deposits with high-starch content required alkaline solutions for reaching high detergency values (close to 85% at 50 °C). The resistance of these complex deposits to mechanical removal changed from strong adhesive and cohesive interactions to reduced cohesive forces as the starch concentration diminished. For deposits with high fat content, the highest detergency value (close to 80%) was reached at 50 °C with the chemical solutions tested, being pH = 7 the solution which could reduce the environmental impact of the cleaning process. For deposits, which showed low cohesive/adhesive forces, chemical action was not required to reach the required cleaning efficiency. The use of α-amylase or lipase (0.2 g/L) did not significantly improve cleaning, suggesting it is not recommended for either high-starch or high-fat deposits.

The multiscale “cleaning map strategy” is shown to be an effective approach to visualise the influence of Sinner factors on the cleaning of fat/starch deposits, allowing selection of the most appropriate conditions to achieve the required level of cleanliness with the lowest environmental impact.