Rapid methods for assessing surface cleanliness within the food industry: their evaluation, design and comparison to traditional techniques
The cleanliness of the processing environment is an important factor in both assuring food quality and protecting the consumer from pathogens, consequently, food businesses should continually assess surface cleanliness in order that any problems associated with the 'cleaning' process can be identified and rectified rapidly. There is, however, widespread confusion regarding why, when and how cleanliness assessment should be carried out and, thus, a need to provide the food industry with guidance.
Laboratory and field studies were conducted in order to evaluate the performance characteristics of both microbiological and chemical-based cleanliness assessment methods. Limits of detection were determined together with factors affecting test efficacy and associated advantages, drawbacks and limitations.
The mechanical energy generated during sampling, the absorbency of the bud material and the swab-wetting solution used, all contributed to the efficacy of the traditional swabbing procedure. Overall however, it was the ease with which bacteria could be released from the bud that had the greatest effect and omitting this step via the use of dipslides increased the sensitivity of microbiological assessment. The benefits of using alternative microbiological techniques have also been highlighted, and a novel, swab-based, enzymatic method capable, in just 5 h, of detecting the presence of < I coliform colony cm2 has been developed.
Unlike microbiological techniques, surface dryness had little effect upon the performance of non-microbiological test methods, yet, other factors, including the universality of the component residue being tested for and its intrinsic level within the food debris, did influence the results obtained, demonstrating that choice of method must depend upon the type of food produced. Results also identified key sectors of the food industry for which appropriate test methodology is currently lacking. To fulfil such requirements, an assay for use within high-fat processing environments has also been developed.
Taken collectively, the results demonstrate that given the variability in food debris and surface contamination, no one method is ideal for assessing cleanliness and rather than being interchangeable, test methods should be used in combination. An integrated cleaning assessment strategy has been devised and its implementation should enable food businesses to ensure their cleaning and disinfection procedures are effective and that the food produced is safe and of the highest quality.