Expert reveals whether it's safe to eat ground beef that's gone grey

Food waste is a big problem, with the average household throwing away £470 of edible or spoiled grub each year.

Most of us aren’t going out of our way to be wasteful, of course, but it’s a figure worth bearing in mind when you’re measuring portion sizes, storing your food, and planning your meals.

Of all the things that can go off in the fridge without you noticing, few sting more than spoiled meat. It’s one of the more expensive ingredients on the weekly shop, and if you’re mindful of the ethics of meat production then the idea that an animal died only for its meat to end up in the bin can be pretty unpleasant.

To that end, you might give it a thorough examination before throwing it out, and you might dare to risk eating meat that’s a day or two out of date if it smells and looks all right.

Beef turns brown and then grey as part of the oxidation process (Nenov/Getty Images)

But what if it’s still in date but doesn’t look quite right? That’s a relatively common occurrence where minced beef is concerned, with the red meat occasionally growing grey while it’s sat in the fridge.

If that’s happened to your beef mince, is it still safe to eat?

Before we answer that, let’s examine why it happens. Simply put, it’s oxidation.

“Oxygen reacts with myoglobin (a protein found in muscles), causing the meat to darken,” Brittany Towers, food scientist at The Black Food Scientist, told Simply Recipes.

Within 15 minutes of being exposed to air, fresh meat darkens into the bright red you typically associate with beef cuts.

However, that oxidation continues for several days after the first exposure, and within five days the meat will often have turned grey because of it. In the interstitial phase it will look more brown than red or grey, and that can be the case for meat in the centre of the pack that’s had less oxygen exposure.

The upshot is, if it’s grey but smells fine and isn’t slimy, you’re probably all right to cook it without incident.

However, if it smells off or has a slimy quality, it’s best not to risk it.

Beef mince can be kept fresh in the freezer for up to four months (Monty Rakusen/Getty Images)

If you want to keep it fresh for as long as possible, mark the packaging with the date and bung it in the freezer where it can be kept fresh for up to four months.

Be sure to defrost it thoroughly before cooking it, of course.

When it’s cooked, it should have an internal temperature of 71 degrees C to ensure any potential bacteria have been killed in the cooking process.