It is one of the most basic tasks possible in the kitchen.
But it turns out you’ve probably been boiling your eggs all wrong.
Scientists have worked out the best way to boil an egg evenly so the yolk is beautifully creamy and the egg white is not too watery.
The only bad news, for those used to a quick six-minute soft-boiled egg, is that the new method takes over half an hour.
Material engineers in Italy went through 300 eggs trying to find the best way to prepare one in its shell, in terms of texture, taste and nutrition.
They were comparing a hard-boiled egg, a soft-boiled egg, the ‘sous vide’ version beloved of fancy restaurants, and a completely new technique.
This technique, which switches an egg eight times each between a pan of boiling water and a bowl of cold water, achieves the holy grail, according to the experts.
It overcomes the problem of a perfectly cooked yolk and undercooked egg white, which happens when an egg is boiled in its shell.
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Scientists have worked out the best way to boil an egg evenly so the yolk is beautifully creamy and the egg white is not too watery
Researchers managed to heat the egg white to an optimal temperature of 85°C, and the yolk to almost the perfect temperature of 65°C.
The secret is repeatedly removing the egg from the boiling water and plunging it into cold water, to stop the yolk becoming hard-boiled and solid, while the egg white is gradually heated enough to give it enough bite.
Professor Ernesto Di Maio, senior author of the study from the University of Naples Federico II, whose usual work involves plastics, came up with the ‘periodic cooking’ technique and made all 300 eggs at home in his kitchen.
He said: ‘I thought the techniques we use in materials science could produce the perfect egg, and the result really is exquisite.
‘I have converted 50 of my family and friends to preferring eggs made this way, and they were served up with lemon and pepper at our laboratory Christmas party.
‘It may take 32 minutes to make this type of egg, and I understand many people won’t have the time, but I personally think it is worth it for the people you love, rather than cooking them eggs in the wrong way.’
The study set out to improve on ‘sous vide’ eggs which are cooked for at least an hour in low and constant temperatures, typically between 60°C and 70°C, to give the yolk a creamy texture.
The issue with this, according to Professor Di Maio, is that the egg white is undercooked and looks transparent, while being too runny.
The study set out to improve on ‘sous vide’ eggs which are cooked for at least an hour in low and constant temperatures, typically between 60°C and 70°C, to give the yolk a creamy texture
His team, led by a researcher he later found out does not actually like eggs, used sophisticated mathematical modelling to work out the best way to cook them.
They then tested these out, using three techniques firing light beams at eggs to determine how well cooked they were and their nutrient profile.
Meanwhile eight expert tasters were asked to rate the hard-boiled, soft-boiled, sous vide and periodically cooked eggs, based on qualities including colour, meltability and softness.
Among the results, published in the journal Communications Engineering, it emerged that an egg cooked using the periodic technique had a sweeter and saltier yolk than a soft-boiled egg.
The yolk was much the same as that of a sous vide egg, but the egg white was less soft, wet and transparent.
Its consistency fell somewhere between that of a sous vide egg and a soft-boiled one.
Professor Di Maio said: ‘This egg is easier to spread on toast, unlike a sous vide egg which would soak into the bread.
‘But it is still not suitable to be put in an egg cup and eaten with soldiers, which would require a soft-boiled egg.’
The new technique was found to produce a better egg nutritionally than the other three cooking methods, although the researchers say that more research is needed to understand the reason for this.
Temperatures in the periodically-cooked egg white ranged between 35°C and 100°C during cooking, while the yolk hit a temperature of 67°C and stayed there.
