Clean in place (CIP) process: Effects of geometry, microorganism, fluid dynamic and cold plasma

Abstract

Clean-in-place (CIP) is a method widely used in dairy hygiene. However, some points in the pipelines are challenging due to system geometry and fluid dynamics. Thus, surface modification has been an alternative strategy. Adhesion and hygiene were evaluated in five configurations of tubes contaminated with Listeria innocua and Pseudomonas fluorescens, fluid dynamics in terms of velocity and shear stress, and the antimicrobial capacity of stainless steel modified with cold plasma. L. innocua showed greater adherence than P. fluorescens. The cylindrical pipe and the concentric reduction achieved better sanitation levels, with a final count of less than 1 CFU cm−2. The tee showed the most negligible decimal reduction of cells for both microorganisms, probably due to the formation of stagnation zones. On the other hand, surface modification reduced the initial population, suggesting that this strategy may be useful in controlling adhesion and for the microbiological quality of the surface.