E. coli O157: separation, complex equipment and disinfection

E. coli O157 needs its own attention because fewer than 10 bacteria can cause infection, and the illness can kill or cause permanent harm. The FSA has guidance on controlling it for England, Wales and Northern Ireland. FSS has its own version for Scotland. Both apply to businesses that handle raw food and ready-to-eat food, including caterers, retailers and manufacturers.

Raw and ready-to-eat food must be adequately separated. The FSA lists the options in order of effectiveness. Best is a permanent separate room for each, with its own staff, equipment, utensils and sinks. Next is a permanent area used only for ready-to-eat food. Last is time separation, also called a temporary clean area, which carries the most risk.

If you use time separation, plan the work so that ready-to-eat food is prepared first. There must be no ready-to-eat food in the area while raw food is being handled. Before ready-to-eat work starts again, clean and disinfect the surfaces, equipment and utensils. Staff must wash their hands. Put food on a clean chopping board or in a container, not straight on the worktop.

Complex equipment is equipment that is very hard to clean between uses, because it has small parts or surfaces that are hard to reach. Examples are vacuum packers, slicers and mincers. Using one machine for raw and ready-to-eat food is called dual use. Bacteria can remain inside the machine after routine cleaning and pass into ready-to-eat food.

Complex equipment should not be used for both raw and ready-to-eat food during a normal business day. In practice this means you need separate machines. Label or colour-code them, and keep each in the right area. Keep separate vacuum bags for raw and ready-to-eat food too.

If a machine must change from raw to ready-to-eat use, it has to be fully dismantled and all its surfaces cleaned and effectively disinfected. For a slicer or mincer, the FSA does not consider that this can be done effectively during normal operations. For a vacuum packer, only a competent engineer should carry out the full dismantling. Simple equipment, such as probes and scales, may be shared if the business has decided that this is safe and has the right controls.

Disinfection only works when it is done correctly. Disinfectants and sanitisers must meet BS EN 1276 or BS EN 13697, or an equivalent standard. Look for the standard on the label, or ask the manufacturer.

Chemical disinfection is always a two-stage process. Stage one is cleaning: use detergent to remove grease, dirt and food, then rinse. Stage two is disinfection: apply the disinfectant at the right dilution and leave it for the full contact time on the label. Disinfectant will not work on a dirty surface, at the wrong dilution or for too short a time. A sanitiser is a two-in-one product, but you must still use it twice: once to clean and once to disinfect.

Heat can also disinfect. A dishwasher on a full cycle is a good way to disinfect utensils, provided it is working properly and well maintained.

Here is an example. A delicatessen slices cooked ham and wants to slice raw bacon on the same machine after lunch. Wiping it down between products is not enough. The owner should buy a second slicer for raw meat and keep it separate, or buy the bacon already sliced.