Effects of operating conditions of high pressure washing on the removal of biofilms from stainless steel surfaces

Hosing with water is the most common approach to cleaning in the food industry. Measurements of the removal of Pseudomonas aeruginosa biofilm from stainless steel using a high pressure hose showed that, over the range of pressures tested, impact pressure does not significantly affect microbial removal. Nozzle pressures of 2.5 × 106 and 9.5 × 106 Pa were used, and the distance between the nozzle and target surface was between 20 and 120 cm. When using cold water, microbial removal increased (p < 0.001) from 2.9- to 4.1- to 4.9-log10 as the time exposed to the water spray increased from 5 to 30 to 60 s. With hot water, microbial removal was 4.9-, 5.1-, and 5.2-log10 when using the same exposure times. The use of detergent followed by spraying with water increased (p < 0.001) the removal of organisms to 5.6-log10.