a perfectly boiled egg takes 32 minutes, according to italian scientists
a new periodic cooking method produced better taste and texture than conventional boiling or sous vide
2 minute read
it can be challenging to achieve a perfectly boiled egg. italian researchers claim to have cracked the recipe using a new method they call periodic cooking.
sean gallup/getty images
italian researchers went through a lot of cartons to crack the recipe for what they declare is a perfectly boiled egg. their new method, dubbed periodic cooking, doesn’t require a sous vide machine or other specialized device. by alternating between boiling and lukewarm water eight times over 32 minutes, they claim to have achieved not only even doneness but a higher nutritional content than eggs cooked by sous vide or conventional boiling methods.
the study, published in communications engineering, notes that egg yolks and whites (or albumen) cook at different temperatures: 65 and 85 degrees celsius, respectively. the researchers say standard methods for hard-boiling at 100 degrees are overkill for the yolks, rendering them fully set, while using sous vide to cook eggs in a water bath for an hour between 60 and 70 degrees doesn’t go far enough, leaving the whites undercooked.
it may be one of life’s simple pleasures, but boiling the perfect egg is complex. the whites can be rubbery, and the yolks ringed in green or grey. peeling them is sometimes frustrating, with cooked whites clinging to shards of shell. it’s no surprise that experts are full of tips and tricks.
there’s no one way to boil an egg. for a jammy yolk and set white, chef and author sohla el-waylly advocates lowering eggs directly into boiling water, covering and setting a timer for seven minutes before lifting them out, lightly cracking them with the back of a spoon and transferring them to an ice bath. “if you do that big temperature swing, (the membrane) easily peels off.” others, such as egg farmers of canada, swear by starting eggs in cold water, and some by poking holes in the bottom of the shell with a pin to release the air pocket first.
photographs of the raw, hard-boiled (red), soft-boiled (yellow), sous vide (green) and periodic (blue) eggs.
pellegrino musto and ernesto di maio
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study author pellegrino musto, a polymer expert at the national research council of italy, and colleagues delved into the physics behind cooking an egg to devise their periodic cooking method. first, they simulated the process using fluid dynamics software. they then transferred their learnings to fresh hen eggs purchased from a naples supermarket and a heater, pan and food thermometer.
the researchers compared hard-boiling (12 minutes in boiling water), soft-boiling (six minutes in boiling water), sous vide (one hour in a 65-degree water bath) and periodic cooking, which involved alternating between boiling water (100 degrees) for two minutes and lukewarm water (30 degrees) for two minutes, eight times, for a total cooking time of 32 minutes.
finally, they tested the cooked eggs for insights into their colour, consistency, taste, texture, chemical properties and nutritional profile. in addition to their superior sensory qualities, the periodically cooked egg yolks contained more polyphenols — compounds with antioxidant properties that studies suggest have health benefits.
the authors concluded: “analysis of the colour, texture and consistency of all the egg products was only the final proof of a successful cooking experiment that might inspire new fancy recipes, proving how knowledge of the science behind simple problems can improve even the slightest bits of our daily life, like the simple act of eating an egg.”
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