Hygienic Quality of Floors in Relation to Surface Texture

Abstract

The relative cleanability of seven floor materials was investigated in the laboratory. Test plates were contaminated by a one-day biofilm of Pseudomonas fluorescens containing spores of Bacillus stearothermophilus as a cleaning tracer. The test procedure involved cleaning and disinfecting operations. The classification of materials was different in terms of residual spores (resulting from removal efficiency only) and in terms of residual bacteria (resulting from removal efficiency and bactericidal efficiency). Measurements of contamination post cleaning were also made on test plates which had been inserted in the floor of a cheese-processing site and subjected to habitual fouling-cleaning cycles for four weeks. The comparison with laboratory results showed that the classification of materials obtained in the field study in terms of residual contamination was close to the one obtained in the laboratory in terms of residual spores. These results indicate that the hygienic quality of floor materials in industrial conditions is linked to their cleanability, rather than to their disinfectability. A geometrical replica of each test plate surface was made using a two-step procedure: a cast of the plate was taken with a silicon-based resin; a polyurethane-based replica was then obtained from the cast. There was a close correlation between the classification of materials in terms of cleanability obtained with replicas in the laboratory and the classification of materials in industrial conditions. This result demonstrates that the cleanability of floor materials is linked to their surface texture. Surface roughness of materials was assessed using four standardized parameters. The results refute the criterion of mean roughness as a guide to cleanability and highlight the influence of grooves extending below the core profile upon hygienic quality of floors.