Scientists have highlighted simple mistakes people make with their fridge which turn it into a nest of bacteria. The whole purpose of a fridge is to preserve food for longer without it spoiling and potentially causing serious illness.

However experts have said a simple oversight in the temperature of your fridge can encourage the growth of bacteria such as Listeria, putting your health at risk without you even realising it. Many households do not reach the recommended level of cold, which endangers food safety. Ideally, it should be kept between 0 and 5 degrees Celsius.

When the temperature rises too much, bacteria find a favourable environment. Experts say that one thing to consider is that fridges are not the same temperature all the way through – and some areas are colder than others.

The back part is usually colder than the door, which warms up easily when opened. Placing products like milk in that area is a common mistake, experts say.

According to a study conducted by experts from the University of California (United States), an average of 11.4 million bacteria inhabit every square centimetre inside the fridge. Beatriz Robles, a food technologist and dietitian-nutritionist, explained to CuídatePlus “The first thing to clarify is that refrigeration temperatures do not destroy microorganisms; they only slow down their growth.

“Some bacteria, like Listeria monocytogenes, can multiply at temperatures of 5ºC, so it is recommended to keep the fridge below this temperature to prevent these microorganisms from reproducing. That’s why temperatures between 5ºC and 60ºC are called the danger zone.”

Additionally, most people do not interpret the temperature controls correctly. This results in food not being well preserved even if the fridge is working.

Things to do to stop fridge warming up:

• Frequently opening the door or leaving it open for too long causes an increase in temperature inside the appliance.
• It’s preferable to organise the contents well to find things quickly.
• A good measure is to leave at least a quarter of the space free for air circulation.
• Storing products like tomatoes or potatoes in the pantry also helps.

Although cold slows down the growth of many bacteria, some like Listeria can resist and multiply. This microorganism poses a significant risk, especially for pregnant women and older people. It can be present in foods such as soft cheeses, deli meats, or smoked fish. Separating raw foods from ready-to-eat ones is crucial. And of course, it’s not enough to smell: food can seem in good condition and not be.

High-Risk Foods and Areas

Ms Robles said some foods generally present more risk: “They are all those that can be consumed without thermal treatment (cooking) or any other type of processing (ready-to-eat foods): cooked ham-type meats or cold cuts, especially sliced ones; smoked fish; dairy products made with raw milk; cooked shellfish; dressed salads; prepared dishes consumed cold…”

Most of the bacteria in fridges was found to be on internal walls with 61% of pathogenic bacterial species are located at the bottom of the fridge, according to a study in Italy. Regarding different storage areas, Italian researchers point out that most microbial flora concentrates at the bottom part of the fridge where fruits and vegetables are usually stored.

How To Avoid Bacteria infection

Ms Robles highlighted the problem of putting food in the fridge without packaging it correctly; “for example, meat or fish wrapped in the paper or bag they give us at the butcher’s/fishmonger’s instead of changing it to an airtight container such as a jar’.”

“Bear in mind that the lower areas are the coldest and this is where raw food should be placed, leaving the upper shelves for cooked food, yoghurts, eggs, etc. Putting in the door those foods where the temperature difference makes it easy for micro-organisms to grow, which is the case with eggs.”

Not cleaning the fridge properly.

Not respecting expiry dates is an issue, Ms Robles said: “This date is only valid until the food is opened. Once opened, it cannot be kept in the fridge for more than 2-3 days. Sometimes, the packaging itself indicates how many days it can be kept open, and this period must be respected.”