Abstract

Cleaning and disinfection agents were evaluated against selected bacteria on three surfaces: aluminium, stainless steel and fibre re-enforced plastic, used as cargo container linings and to access their effect on the surface integrity. Nine sanitation chemical solutions: benzalkonium chloride, sodium hypochlorite, nitric acid, levulinic acid, peracetic acid sodium hydroxide, sodium dodecyl sulphate, AT special (commercial detergent) and Disinfect Maxi (commercial disinfectant) were tested against seven bacteria strains: Escherichia coli K12, E. coli DSM 682, SalmonellaSenftenberg DSM 10062, Salmonella Typhimurium P6, Pseudomonas aeruginosaDSM 939, Listeria monocytogenes Scott A and Listeria innocua P577 in dirty condition as described by standard bactericidal test both in suspension and on the three surfaces. With the exception of sodium dodecyl sulphate (SDS) and AT Special (ATS), the others were efficient in reducing the live bacteria counts as required by the standards for six of the bacteria both in suspension and on the three surfaces; L. monocytogenes Scott A was the exception. Only peracetic acid was able to disinfect all seven strains on all surfaces (> 4 log CFU reduction) as well as in suspension (> 5 log CFU reduction) as required by the standards. Accelerated corrosion tests also showed that most of the disinfectant will likely compromise the integrity of the surfaces. Only peracetic acid at the concentration used had minimal corrosion effect. A novel index for practical usability was created to take into account disinfection efficacy and low corrosiveness; peracetic acid had the highest usability index from the chemicals tested. Peracetic acid based disinfectants will be appropriate for an environment with the composite materials studied as found in some cargo containers. Combining disinfection studies, corrosion studies and the index of the two can assist the food and allied industries in making cost-effective choices for disinfectants depending on surface materials present.

Key words: Detergents, bacteria, cargo container surfaces, disinfectant.