Stale biscuits are unlikely to cause harm, and you can scrape a little mould off your jam – but never risk it with dairy, fish or dips such as hummus, say scientists
Many of us are guilty of leaving food in the fridge or at the back of cupboards until it expires or begins to rot. Figures show that around 9.52 million tonnes of food are wasted annually – enough to feed more than 30 million people.
But should you take the risk of consuming food past its use-by date? There are around 2.4 million cases of food poisoning in the UK each year, and while most people recover within days, it can be more serious for vulnerable groups such as the elderly, immunocompromised, pregnant women, or young children.
Natalie Stanton is a chartered environmental health officer and founder of The Safety Expert – an organisation which provides food-safety training for hospitality teams. She says some food such as dairy products are no-gos, but others may just pass the test of time.
Stanton reminds shoppers that a use-by date shows the last date a product is safe to eat. ‘’A packet of ham or a bottle of milk will have a use-by date on it and that’s the one that the consumer should follow.’’ says Stanton. “The risk if someone ate a product past the use-by date is that they will get food poisoning.” The sell-by date is for the retailer rather than the consumer. The best before date is about the quality of the food, not safety. “If someone ate food after the best before date in most cases it wouldn’t make them ill,” she says. In fact, some supermarkets like M&S removed best before dates from their products in a bid to tackle food waste.
Use-by dates are determined by a shelf-life testing process carried out in laboratories, says Stanton – foods are stored in a fridge at various temperatures for different periods of time. They monitor the levels of bacteria to work out at what point do these levels get high enough that they could cause food poisoning,” she explains.
The use-by date is usually one or two days before the actual shelf-life found in the test, to ensure added safety.
Stanton says use-by dates are non-negotiable for most perishable food items – for example meats, fruits and vegetables, and a variety of dairy products such as yoghurt and milk. Products we tend to store in cupboards such as a pack of biscuits have a longer lifespan and are less of a concern for bacteria growth or poisoning.
“If we use the example of a pack of biscuits, if you ate them after the best before date you might just find they’re not as crunchy. They’re just a little bit stale but it’s not going to make anyone ill.’’
Don’t follow your nose
Professor Erik Millstone, a professor of science policy at the University of Sussex and one of the UK’s leading independent scholars of food safety policy, discusses how he has “heard it said foolishly by quite a lot of people, ‘just smell it and if it smells okay, it’s bound to be okay.”
This “is not a reliable guide to food safety”, he says, and Stanton agrees, as some bacteria can’t be seen, smelt or tasted. “Food could literally smell, taste and look fine, but bacteria could still have multiplied to unsafe levels”.
Hummus and bagged salad – the surprising foods that can cause food poisoning
Millstone says use-by dates are important to follow since they “are primarily about safety”.
That’s especially true with meat, fish and dairy which he describes as “the most perishable” foods, as “bacteria can thrive and grow” in them.
He also warns against taking risks with eggs which, though often considered a long-lasting staple, certainly “can go off” and “deteriorate”.
“It certainly remains the case that most egg-producing facilities are contaminated with salmonella and campulobacter for that matter, and some eggs are contaminated with those bacterial, and the longer you keep them, the greater the risk that the population of bacteria will have grown.”
Surprisingly, leafy and pre-packaged salad can also be a cause of food poisoning – so eat it within the use-by date. If you see slime on a vegetable or a bag of salad, throw it away – it’s caused by bacterial colonies on the surface.
“We can’t always be sure that the soil on which leafy salads and vegetables are grown hasn’t previously been treated with manure” says Millstone, adding that salad, and all fruit and vegetables should be washed before eating. If your salad or vegetable has got slime on it.
Another food that can be tempting to eat past its best is miso. As a fermented food, it tends to have a long shelf-life, but Millstone says he himself once got “terrible food poisoning” when he ate some after its use-by date. So use common sense.
Dips such as hummus tend to have a short expiration date once opened, meaning it’s tempting to take a risk rather than waste the pot. But once the lid is opened on a fresh food such as this, airborne bacteria start to settle on the top – so it really does only take two days for them to become unsafe to eat.
Scrape the mould off jam – but don’t eat mouldy nuts
Ever considered scraping the mould from a jar of pesto or jam? They tend to last a bit longer than other foods because salt and sugar can slow down the development of bacterial moulds, explains Millstone, although they don’t prevent it.
He advises: “If you’ve got a jar of stuff, which is half-used, but the mould is confined to a little bit at the top, you could wipe that off. But if there’s mold over the entire top surface of the product then I discard the lot.”
If a hard cheese such as parmesan or cheddar has a small amount of mould, it’s also generally considered safe to cut it off and carry on. Bacteria needs moisture to thrive, so doesn’t tend to penetrate beyond into a dry cheese.
But experts advise to follow use-by dates with nuts, and never eat them if they’re mouldy.
“Nuts are prone to fungal growth”, which is “toxic” but “in a different way from bacteria”, says Millstone.
He says pistachios are “particularly vulnerable” to this.