ATP bioluminescent techniques are increasingly used for measuring the efficiency with which surfaces and utensils are cleaned. In late 1990s, a survey of 500 food manufacturing businesses in the UK revealed that 48% of respondents used swabbing followed by bacterial culture, while 27% used ATP bioluminescence. To adequately sanitize a food contact surface, it must first be washed to remove any food residues that could act as a nutrient source for the subsequent growth of microorganisms. After washing, the surface is sanitized to kill the residual microflora. If either process is not done properly, food particles and/or microorganisms can remain and may constitute a risk to the quality and safety of foods to be processed afterward. Normal swabbing and plate-counting procedures only detect microbial contamination of the surface and may not indicate whether the surface has been properly cleaned. ATP bioluminescence detects contamination from both sources within 2 min and is considered a more reliable indicator of the overall hygienic condition of the area tested.
Several studies have compared the results obtained by standard microbiological techniques and ATP bioluminescence for assessing surface cleanliness. Some reported a good correlation between these methods, while others have obtained a poor correlation. Such discrepancies in findings could be explained either by the different nature of the surface and surface contamination (presence of spores for example) or the inability/inconsistency of swabs to pick up microorganisms effectively. Loss in bacterial viability during drying could also have an impact on both ATP bioluminescence and plate-count results. In addition, the presence of detergents, sanitizers, or other chemicals may interfere with bioluminescent reactions, leading to false-positive or false-negative results. Despite these difficulties ATP bioluminescence has been used successfully as an initial step in hygiene monitoring, especially within HACCP (hazard analysis critical control point) plans. Most of the ATP-based reagent kits produced for rapid surface cleanliness tests (Enliten Total ATP Rapid Biocontamination Detection kit; Clean-Trace Rapid Cleanliness kit; PocketSwab, Charm Sciences, Inc.) rely on the use of a baseline cut-off value that should be determined for every tested environment. The procedure involves the following steps.
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