We always tend to think that sandwiches are low risk and can be left out for as long as is needed. Unfortunately, sandwiches are much more riskier than we think they are. There is a microbiological risk in sandwich making that affects sandwich food safety.
In reality, it is the sandwich fillings that create the risk. Sandwich fillings are perishable, uncooked products that usually undergo no heating or sanitising. And are made by hand throughout the production process.
Let’s consider the most common fillings:
Each of these foods have at some stage or another been implicated in food poisoning outbreaks. Lettuce and cucumbers are the most common foods that carry E.coli O157:H7. Which is the pathogenic strain of E.coli which causes internal hemorrhagic bleeding of the gut. This type of bacteria occurs naturally in the soil, and can cause contamination from unwashed vegetables.
Chicken mayo and deli meats have been implicated in serious cases of Listeriosis, Salmonellosis and a number of cross-contamination cases involving Campylobacter.
It then seems strange that we would consider sandwiches as low risk foods. There are definite microbiological risks that can affect sandwich food safety.
Adding to the concerns are how sandwiches are treated during preparation and display. Sandwiches are usually prepared in large portions. Which means the fillings are made in bulk. Depending on the amount prepared this can usually take up to two hours or more. This already means that these fillings have been at ambient temperature for a long period.
Sandwiches are usually prepare by hand. Meaning over a two hour period , how often would the chef wash their hands between handling the different food groups? Sandwiches are then plated, covered and then left out until needed. When serving sandwiches these are also usually hand dished. Meaning more opportunity for cross-contamination.
Let’s consider these items in terms of a salad. By law salads must be held and displayed below 5 degrees C (41 degrees F). This is because of the potential risks of allowing bacteria to grow to high levels causing food poisoning. Salad items are hardly washed before use, and never cooked.
Sandwich fillings should be pre-prepared, kept in a fridge until ready to put together and serve. This means slicing the cheese, portioning the lettuce, cutting the cucumbers, mixing the chicken mayo etc.
Then placing in the fridge.
The bread or rolls etc, should then be prepared and buttered.
Once this is ready, the filling can be added and finished off.
Sandwiches should be displayed cold, as you would with salads, yet the bread presents difficulties in doing so, which generally relates to quality.
There then needs to be some compromise. Let’s consider some real risk factors.
The danger zone for the growth of bacteria is between 20 – 45 degrees C ( 68 – 113 degrees F) . This is range at which food related bacteria grow most rapidly. At the very least all foods must be kept out of this range.
From a real risk perspective, cold foods and in this case sandwiches only start to show risk once above 10 degrees C (50 degree F) . Bacteria in general will not grow or will at least be minimised within this range.
This does mean that it is time dependent, meaning that bacteria will eventually grow below 10 degrees C ( 50 degrees F) after a certain period.