Food Safety News – April 2011
Thermal disinfection – hot or not?
The recent Food Standards Agency (FSA) guidelines on practices to reduce to the verotoxigenic strain of E. coli O157 have laid out a number of requirements for cleaning practices, and in particular the use of thermal disinfection in dishwashers to reduce bacterial numbers to a safe and acceptable level.
Commonly used practices such as hand washing, colour-coded equipment, and chemicals are all very effective, if used correctly. This will however require adhesion to the manufacturer’s instructions concerning dilution and contact time. Chemical disinfection will be appropriate if instructions are followed. Any chemical disinfectant must meet the following BS standards
- BS EN 1276: 1997
- BS EN 13697: 2001
Chemical disinfectants are not designed or intended to remove dirt or grease and are only effective if used on a surface which is clean and free from residue.
Many caterers prefer to use a ‘two-in-one’ product such as a sanitiser. Any sanitiser used would also need to meet the BS standards mentioned above. As sanitisers are used to remove dirt and grease and then reduce bacteria numbers also, they are limited in their effectiveness at each task. Sanitisers are often described as doing a ‘little bit of both jobs’, when it comes to cleaning and disinfection. This one stop, ‘wash and go’ method would not be considered as an appropriate control for the destruction of E. coli O157. Any sanitiser would need to be used in both stages of cleaning in order to be considered effective; once as part of the main clean to remove the dirt and grease and then again as a disinfectant to reduce bacteria to a safe level. This principle may have escaped the attention of many Food Business Operators (FBOs).
Thermal disinfection was singled out as being especially effective in the destruction of the micro-organism E. coli O157.
“The application of heat (thermal disinfection) is one of the most reliable ways of killing bacteria such as E. coli O157…. Where heat disinfection is being used, food businesses should ensure that the temperature and contact time is sufficient to destroy harmful bacteria.”
http://www.food.gov.uk/multimedia/pdfs/publication/ecoliguide0211.pdf
For premises that require approval, it is a legal requirement that washing equipment reaches a water temperature of 82°C or to have an alternative system in place which has a similar effect. As with other forms of disinfection, dishwashers are only effective if they are maintained and kept in a clean condition. A build-up of grime, grease, film or lime-scale will have a detrimental effect on the dishwasher’s performance. A regular deep clean, and if required de-scale would all aid the effectiveness of the dishwasher.
Adequately maintained commercial dishwashers should be capable of reaching 82°C or have a water reservoir maintained at least 80°C in order to be considered appropriate, if contact time of at least 15 seconds can be assured. It is the FBO responsibility to ensure that their dish washing procedures are reaching and maintaining an appropriate standard, and that the FSA guidance on E. coli O157 is being adhered to. Failure to do so may have catastrophic consequences with closure, prosecutions, and even possible E. coli O157 outbreaks as a result.
How do you know what rinse temperature your dishwasher is reaching?
There is a temperature testing device that is so simple to use and has proved to be so accurate that it has been approved for use in flight by airlines and hospitals.
The Thermal Disinfection Indicator (TDI) uses melt point technology to provide a permanent record that the chosen operating temperature has been correctly reached. The general dishwasher temperature of 65°C is considered acceptable however, some applications stipulate 82°C hot tank temperature relating to 71°C for full thermal disinfection. TDI provides the means to confirm that this hotter wash cycle has been correctly achieved.
TDI's success is the special adhesive backing that can not only withstand the full wash cycle but can also be simply peeled off at the end of the line and stuck on the weekly check-list, providing a permanent traceable record of the dishwasher's performance. Simply stick the label on a metal platter or container, put it in the dishwasher for a normal cycle and take the reading at the end. The result is irreversible, and the label can be stuck on your records.
Visit our shop to place your order at
http://shop.hygieneauditsystems.com/dishwasher-rinse-temperature-tester-x25-21-p.asp
Please call us on 01727 866779 or email sales@hygieneauditsystems.com for more information
