Clean in place (CIP) of different stainless steel geometries contaminated with Pseudomonas fluorescens

Abstract

The presence of biofilms on food processing surfaces is a constant concern and can cause economic damage and impacts on public health. The aim of this work was to evaluate the development of P. fluorescens on the stainless steel surface, to analyze the CIP (clean in place) hygiene considering different geometries, to investigate the flow fluid dynamics and to determine the consumption of the inputs in this process. A circulation line with the characteristics of a dairy was used. The surface sampling was done using the swab technique and the performance of the process was evaluated based on decimal reductions considering the initial population adhered. The fluid dynamics study was carried out with FLUENT software and the consumption was determined by means of flow and electric current sensors. The results showed that P. fluorescens adhered to the surface reaching an average of 4.31 ± 0.26 log CFU∙cm-2, with the production of exopolysaccharides during usual time of industry operation. The decimal reduction was not significantly different among the pipe geometries in straight section, elbow, expansion and reduction. The stretch with branching in tee was statistically different from the others due to a zone of stagnation and fluid recirculation. The rinses were the stages that consumed the most water and the alkaline cleaning demanded more energy to execute the CIP. The geometries showed microbiological safety after CIP process, except tee. In addition, the expressive demand for water and energy for the execution of the process was evident.

Rinse model implementation of alkaline detergent in clean‐in‐place process with gradual flow reduction for economy of water and effluent reduction

“…Silva et al (2020) showed that sanitization in certain regions of the piping system occurs more slowly and is harmed due to dead zones, where there is no effective fluid circulation. Li et al (2019) also reported the difficulty of dead zones in CIP cleaning and the problem of the shape of the geometries that reduce the flow velocity and affect the dynamics of removing dirt, residues, and microbial cells.…”

“…In this work, a sodium hydroxide solution with an average purity of 98%, at a concentration of 1% wt, was used as an alkaline detergent, with conductivity equal to 21.8 mS/cm. The detergent solution was prepared and circulated through the system, in a closed circuit, for 15 min at a temperature of 70°C, as related by TetraPack (2015); Wang et al (2019); Silva et al (2020) for CIP process of stainless steel piping system.…”

“…In that region-between one of the branch of the tee and valve V103-the main flow does not occur, which generates a stagnation zone during rinsing and contributes to the slow exit of the accumulated detergent in that region. Silva et al (2020) showed that sanitization in certain regions of the piping system occurs more slowly and is harmed due to dead zones, where there is no effective fluid circulation. Li et al (2019) also reported the difficulty of dead zones in CIP cleaning and the problem of the shape of the geometries that reduce the flow velocity and affect the dynamics of removing dirt, residues, and microbial cells.…”