How to tell if your egg is fresh

Every year, 21,000 tonnes of unused eggs are thrown away in the UK - that's £66m worth each year.

But are old eggs ok to eat, or are they being needlessly wasted? Government advice says consumers should stick to the best before date when deciding whether or not to eat eggs, but some cookery experts say the egg float test will tell you how fresh your egg is.

We asked food safety experts for the lowdown, and what to do if you have more eggs than you can get through.

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What is the egg float test and does it work?

The principle behind the classic egg 'float test' is that if an egg placed in a glass of water floats to the top it should be binned, but if it sinks it's fresh.

However, that's 'fresh', not necessarily 'safe to eat' - and this is an important distinction.

Narriman Looch, head of foodborne disease at the Food Standards Agency (FSA), doesn't advise using this method. 'We don’t suggest using the egg float test as it indicates egg age rather than safety - it can’t show which bacteria have been growing inside the egg,' she says.

While several cookery experts, such as Delia Smith, and organisations including the RSPCA and British Egg Industry Council, suggest using the egg float test as an indication of freshness - something that can make all the difference to a recipe (for example, when you're poaching an egg or baking a cake), none advocate using it after the best before date.

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Other ways to know if your egg is fresh and safe to eat

Eggs have a shelf life of 28 days from the date they are laid (indicated by the 'best before' date) and by law they must reach the consumer within 21 days of that date.

This gives you at least seven days to eat them, but there are a few other things you can check for to determine whether your egg is ok to eat:

• Up to two days after the best before date is fine. Narriman Looch, of the FSA, says: 'Eggs are safe to eat for a couple of days after the best before date [stamped on the egg] but you should make sure both the white and yolk are cooked thoroughly.'
• Don't eat eggs with damaged shells. This is because dirt or bacteria might have got inside. A slimy shell is also an indication that it may have become contaminated and should be thrown away. It's worth checking a pack before you buy so you don't get lumped with duds.
• Check for unpleasant smells. Bin any eggs that have a strong 'eggy' smell before or after cracking. Don't rely on the 'sniff test' alone though - an old egg that smells alright could still have pathogenic bacteria growing inside it.
• Check the consistency. Your egg should have a yellow or orange yolk and the egg white should be gloopy rather than runny. Always crack your egg into a mug or bowl before adding to a dish, or cake mix, just in case it isn't fit for consumption.

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How to choose the best eggs to buy

• Look for the red Lion mark The British Lion safety scheme was introduced in 1998 to reduce salmonella food poisoning cases arising from eggs, and it's been so successful that nearly all (90%) of UK eggs are produced within its guidelines. Lion Quality eggs have a best-before date printed on the shell as well as the box to demonstrate freshness.
• Go for a box with the longest date. Eggs have to be collected from the producer at least twice a week, which means that most Lion Quality eggs are delivered to the supermarket within 48 hours of being laid. While this gives plenty of time to eat them, if you only eat them occasionally it's best to opt for the longest best-before date you can.
• Don't get too hung up on fancy eggs. Various factors contribute to why an egg is more expensive, including if they're organic or come from fancy 'heritage' breeds. However, there's no real nutritional benefit to choosing these rather than cheaper ones - for example, all eggs contain omega 3 essential fatty acids, even those that aren't specially marketed as such. Higher cost does generally indicate a higher-welfare egg , but you can still usually get free-range options for less, especially from supermarket own-brands. 

What to look for if you're buying farm eggs

Eggs bought directly from a producer - such as at a local farmers' market - won't necessarily be stamped on their shells with the Red Lion Mark but the producer is required under food labelling regulations to sell them in a box with:

• the name of the food
• the name and address of the producer
• best before date (28 days after laying)
• advice to consumers to keep the eggs chilled

Without this information, you can't guarantee anything about the egg, such as provenance and when it was laid.

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How to store eggs to keep them fresh for longer

• Keep eggs in the fridge in their original box. Helen White of Love Food Hate Waste says: 'I recommend storing eggs in their box in the fridge to keep them at their best.' Not only does the box protect the eggs and show the best before date clearly, it helps to prevent bacteria and other food odours seeping through the eggshells' tiny pores.
• Store eggs at a steady temperature, below 20 degrees C. Extreme temperature changes, such as moving from a hot car to a fridge, can lead to condensation on the surface, which leads to an increased chance of Salmonella from outside the egg penetrating the inside. If you're not storing them in a fridge - for example, in a pantry - make sure it's cool and dry with a relatively constant temperature.
• Freeze eggs. You can freeze eggs for up to six months. Just make sure you do it before the best before date has passed. Crack them open, beat them and freeze in a container. Don't freeze eggs in their shells or they'll explode. Helen advises blending the yolks a little and adding a little salt or sugar before freezing to stop the yolks going sticky, and labelling whether they are sweet or salty to avoid surprises when you defrost them. You'll also need to bear in mind the extra salt or sugar content when cooking with them.
• Only defrost what you need. Three tablespoons (around 60ml) of thawed whole egg is equivalent to one egg. Freezing individual eggs in a muffin tin, then popping in a bag, makes it easier to use one at a time.

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Egg myths busted

Don't fall for these common misconceptions and sneaky marketing tricks. We separate fact from fiction:

1. A darker yolk means a better quality egg 

Not necessarily. Egg producers can game the colour of the yolk by adding certain ingredients into their feed, so a bright orange yolk doesn't guarantee a healthier egg or better welfare for the bird.

Ingredients such as marigold, grassmeal, capsicum, maize and citranaxanthin are natural carotenoids which impact yolk colour.

Egg producers can choose what colour they want the yolk to be from a DSM colour fan of 16 shades (the globally recognised industry standard) from pale lemon through to rich orange, depending on consumer preference, and use feed that will produce that colour accordingly.

2. Brown eggs are healthier than white ones

Not true. Brown shells don't mean a healthier egg than white ones - they contain the same nutrients.

From an animal welfare perspective, white eggs are actually better because the chickens that lay brown eggs can be more aggressive than those that lay white ones and tend to have their beaks trimmed shortly after birth to stop them pecking each other - a welfare issue that the government is keen to stamp out.

3. Eggs are dairy

Definitely not, although it would appear there is some uncertainty about where eggs come from, especially among young adults.

Research by the charity Leaf (Linking Environment and Farming) found that one third of young adults don't know that eggs are laid by hens and one in 10 believe that eggs come from wheat or maize.

Confusion may arise because they are often categorised in supermarket dropdown menus with dairy products - for example, 'milk, dairy and eggs' - or because vegan diets exclude both eggs and dairy so people may think they originate from the same source.

Dairy only includes foods produced from the milk of mammals such as cows, while eggs are laid by birds.

4. Eggs are high in cholesterol

For many years, people were advised to limit egg consumption because they were found to be high in cholesterol and it was thought that cholesterol in food contributed to raised blood cholesterol levels and, in turn, a higher risk of heart disease.

However, current research shows that saturated fat in the diet has a far greater effect on blood cholesterol levels than dietary cholesterol - so much so that previous advice to only eat three or four eggs a week was scrapped by the Department of Health in around 2000.

The only exception is people with familial hypercholesterolaemia, where the liver is unable to remove excess 'bad' LDL cholesterol, who are advised to eat no more than three or four a week. But even they might be pleased to know that the amount of cholesterol in UK eggs is less than it was a few decades ago - thought to be because the ratio of white to yolk (which is higher in cholesterol) has increased.

Remember - how you cook an egg and what you eat it with could contribute to higher saturated fat consumption. For example, scrambled egg with smoked salmon is healthier than a fried egg with bacon.

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