The Science Behind Keeping Food Cold

by Jackie Edwards

1 in 10 people around the world become ill from after eating contaminated food. Chilling and freezing food is essential in preventing bacteria from multiplying on it, which can lead to illnesses, including food poisoning. However, sometimes bacteria can grow quicker than you’d think and by the time it’s chilled it may have already got bacteria growing on it. Research has helped our understanding for the best methods of chilling and freezing food to prevent bacteria growth and food poisoning.

Refrigerate When It’s Hot Or Cold?

It’s a common question whether you should let food cool down to room temperature before putting it in the fridge. Before modern fridges came along it was a good idea to let food cool down because putting hot or warm food in a fridge caused the temperature of it to rise, affecting everything else in the fridge. However, technology has made fridges more powerful and they can now easily handle warm food being put in them without the temperature of the fridge increasing much. Wait for food to stop steaming and when it reaches 60°F it can go in the fridge. This is better for food as it doesn’t give bacteria chance to multiply which is a common cause of food spoilage and poisoning.

Bacteria In Your Ice Cream

It’s an assumption that putting food in the freezer stops bacteria from growing or that it kills bacteria altogether. Most bacteria can’t survive in freezing temperatures, but unfortunately, this is not the case for all bacteria and some thrive in the cold environment. Freezers limit water and food sources, but some bacteria will thrive on frozen sugary foods, dairy and meat products. Ice cream contains a high sugar and dairy content, making it a perfect breeding ground for bacteria. One case in Kansas found at least three different strains of the Listeria bacteria in ice cream that led to five people being hospitalised and three dying. A study in Egypt found 42 out of 100 ice cream samples contained faecal coliform and 37 contained Klebsiella.

Stop Cross Contamination  

If you suspect that your freezer may have had a food in it that had bacteria growing on it then the best thing to do is to throw all food away and thoroughly clean your freezer. This is because the bacteria could have spread further than the originally contaminated food and it has the potential to grow on other foods and the sides of the freezer. You should also store food in containers in the fridge and freezer. This does take up more space, but it will keep food fresh and prevent cross contamination, so it can be beneficial to have a big enough fridge/freezer to adequately store food. This can prevent an outbreak within your fridge or freezer and the containers can be easily cleaned instead of having to throw food away or unknowingly eat contaminated food.

Food poisoning and other foodborne illnesses are often preventable, yet so many people are affected by them every year. A lot of this is down to a lack of knowledge and understanding about safely storing food in the fridge and freezer. As soon as food has stopped steaming, put it in your fridge to prevent bacterial growth. Be aware that bacteria can grow in cold temperatures, so use containers to separate food and prevent bacteria spreading.

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