Efficacy of low-pressure foam cleaning compared to conventional cleaning methods in the removal of bacteria from surfaces associated with convenience food.

Background: Food borne illnesses and food poisoning are cause for concern globally. The diseases are often caused by food contamination with pathogenic bacteria due largely to poor sanitary habits or storage conditions.

Objectives: Prevalence of some bacteria on cleaned and sanitised food contact surfaces from eight convenience food plants in Gauteng (South Africa) was investigated with the view to evaluate the efficacy of the cleaning methods used with such food contact surfaces.

Methods: The microbial load of eight convenience food manufacturing plants was determined by sampling stainless steel food contact surfaces after they had been cleaned and sanitised at the end of a day's shift. Samples were analysed for Total Plate Count (TPC), Escherichia coli, Salmonella species, Staphylococcus aureus and Listeria species.

Results: Results showed that 59 % of the total areas sampled for TPC failed to comply with the legal requirements for surfaces, according to the Foodstuffs, Cosmetics and Disinfectants Act (< 100 cfu.cm(-2)). S. aureus and Salmonella were not detected, but Listeria was detected in 23 % and E. coli in 1.3 % of the samples. Fifty percent (50 %) of the plants applied conventional cleaning methods for cleaning and sanitation and 50 % used the low-pressure foam (LPF) method. There was significant difference (P ≤ 0.05) between the mean TPC values of the conventional cleaning method (14 358.82) compared to that of LPF method (2 386.51) but no significant difference (P > 0.05) in terms of Listeria species isolates obtained from both cleaning methods. The LPF method proved to be the superior cleaning option for lowering TPC counts.

Conclusion: Regardless of cleaning method used, pathogens continued to flourish on various surfaces, including dry stainless steel, posing a contamination hazard for a considerable period depending on the contamination level and type of pathogen. Intensive training for proper chemical usage and strict procedural compliance among workers for efficient cleaning procedures is recommended.