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The truth behind ‘Use by’ and ‘Best before’ dates

What have mobster Al Capone and food labelling got in common?


His family lobbied for food dating on milk!

Listen to The Curious Consumer podcast as food microbiologists Linda Gordon and Mairead McCann investigate food labels and why we need them.

A short history of food labelling

According to legend, the Capone family, who had a big hand in the U.S. dairy industry in 1930s, lobbied for dating on milk when a family member got sick after drinking contaminated milk.

About 20 years later, sell-by dates were introduced in Marks & Spencer's storerooms and then made their way to the shelves in 1970s.

Sniff testers vs food science

While some still prefer to go-by-their-nose to check if food is safe to eat, food-dating means we can avoid eating unsafe food because even unsafe foods can look, smell, and taste good.

The “use by” date is a safety measure and gives a deadline telling us when our food will become unsafe to eat. So even if your food passes the sniff test with flying colours, we need to stick to the “use by” date rigidly as the food could still be contaminated – and make you ill.

“Use by” dates on food packaging have been worked out by scientific testing. The kind of foods with a “use by” date are perishable foods usually found in chilled display units, such as cooked meats, dairy products, and prepared salads.

“Use by” vs “Best before”

While you should never eat food past its “use by” date, the “best before” date gives you a little bit of wiggle room. It refers to quality, so food is still safe to eat after the given date, but the flavour, smell or texture may be affected. “Best before” is used on foods with a longer shelf-life, like pasta, tinned foods, breakfast cereal. Bacteria can’t usually grow on these foods so food poisoning is not a concern.

The golden rule to remember is that use-by date is a DEADLINE but best before is a GUIDELINE, for when to eat your food.

Understanding food labels helps us to avoid serious illness. Food past its “use by” date could contain the food poisoning bacteria Listeria. Given the chance, Listeria bacteria will grow rapidly in food and unlike other food poisoning bacteria Listeria can also grow slowly at refrigeration temperatures.

For healthy adults, Listeria usually produces no symptoms, or a mild flu-like illness. But for those with weakened immune systems or who are considered vulnerable Listeria can cause very severe illness or even death.

“Use by” and food waste

“Use by” dates play an important role in reducing food waste. Did you know that in Ireland, consumers produce 300,000 tonnes of food waste every year? And safefood research has shown that up to 30% of the food we purchase is thrown away and it is estimated that upwards of €20 a week is wasted on throwing out food.

So to avoid wasting food when you are at the shops check the “use by” dates to avoid buying food that will need to be used quickly. When storing foods put new items to the back, and older items to the front. As food reaches its “use by” date make sure to eat it, cook it or freeze it and this will help will to avoid unnecessary waste.

Video: How to read food labels

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