Use-by dates are a food-safety matter so you should always take them seriously. Here’s a guide to where you do – and definitely don’t – have some leeway
One news event you may have missed this month was that Tesco lost a judicial review over selling foods past their use-by date. The company had been taken to court by Birmingham city council, and was launching a challenge using the evidence of the food microbiologist Slim Dinsdale, a swashbuckler of the pathogenic world, who favours the “smell it and see” approach. All of this was over-ruled by judges, who decided that use-by dates were, overall, still important enough for public safety to be observed.
This was, of course, all overshadowed, by the coronavirus outbreak; but the use-by date controversy has never been more up to date. The cook, author and campaigner Jack Monroe runs ad hoc advice sessions called Lockdown Larder on Twitter, and says: “Since I’ve been doing it, by a country mile the most-asked question I’ve had is: ‘I’ve got this yeast, it went out of date two months ago, can I use it? I’ve got these sardines, they went out of date a year ago, can I use them?’ People want someone they perceive to be an expert to reassure them. As a species, we seem to have lost the ability to trust our own senses.”
This gets to the core of the matter. If you want a blanket rule for everyone, the use-by date is that rule. I can only tell you what I would eat. If it happens to be the same as Theresa May (who famously admitted to scraping the mould off jam), that’s just coincidence.
Erik Millstone, emeritus professor of science policy at the University of Sussex, lays out the ground rules: ignore sell-by dates. “Those are a guidance by the retailers for the retailers, so they can manage their stock. The indications concerning food safety, particularly microbiological food safety, that’s use-by dates.” But are all use-by dates created equal?
Eggs, strictly speaking, don’t have a use-by date but a best-before-end (BBE), which is mostly to do with quality and taste rather than safety. Either way, this is a hill I’m prepared to die on: dates are irrelevant to eggs, because of the float test. Drop the egg in a glass of water. If it floats to the surface, it’s definitely off. If it sits flat on its side, it’s definitely fresh. If it sits vertically, it’s somewhere between fresh and off (I would still eat it). A fully off egg will also smell disgusting, but you can save yourself that trauma by conducting this test.
The sulphurous smell of an off egg triggers a useful disgust mechanism, because the bacterium causing it – Pseudomonas – can be injurious. Salmonella is far more dangerous, being undetectable, but British hens are inoculated.
If a bread past its BBE date is mouldy, or smells of mould, don’t eat it. Don’t just chop off the mouldy bit, because there is a twilight when mould spores are present but not yet visible. Mould on bread isn’t the most dangerous of the fungi, but it’s still revolting.
I remember being astonished to read (in Delia) that you should do a complete spice overhaul every year, because they won’t taste as good. As I have spices that are older than my children; this seemed extremely wasteful. There are spices that most cooks won’t get through in a year (za’atar) unless you live with Yotam Ottolenghi. But Delia’s right, if you want them to last longer, buy them whole and grind yourself to order, or go back in time and store them in brown rather than clear glass.
Ah, this is where things get interesting. Millstone says: “Some of the compounds formed from mould can be seriously toxic, especially aflatoxins, which can be carcinogenic.” These are found on mouldy grain and nuts.You can’t buy dangerous grains and nuts (because of that blasted EU), but you should take very seriously the use-by date on what you have bought. There is no meaningful trade-off between risk now and cancer later. It’s not like pharmaceuticals; it’s just a bar snack.
Yeast expires because it’s a micro-organism (a fungus, in fact) that eventually dies. Your foaming yeast is still alive and should be fine to use; the expiry date is a decent estimate of how long the yeast will last, but various conditions (where and how yeast is stored among others) affect how long it will live.
Yeast, baking powder and other things that react
Monroe raises the stakes here: “I’ve personally used yeast that is 10 years out of date. But it’s not been opened, and was stored away from direct light in cool conditions. It didn’t rise as well as normal yeast would. If you’re using old yeast, I would always recommend using 1.5 times the amount the recipe states, leave it for an extra hour, and if you’re really running low on flour, make a quarter batch, then if it doesn’t rise, or doesn’t go so well, you can work it into a soda bread and you’re not going to waste half a bag of what is currently quite a precious resource.”
Baking powder and bicarbonate of soda typically have shelf lives of one to two years, but storage is more important than numbers, and there is a school of thought that says bicarb lasts for ever. Yup, for ever.
Harissa, wasabi paste and other things that discolour
Some time before anything goes mouldy, it may go a bit grey (if it started out green) or just a murkier version of itself (if it started out red). This is plain pigment oxidisation and is not dangerous, though it is a bit unappetising – if the fat has oxidised, you will be able to smell it.
IS YOUR YEAST STILL ALIVE? | DOES ACTIVE DRY YEAST REALLY EXPIRE? | IS IT OKAY TO USE EXPIRED YEAST?
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