Slow-cooked egg: 62.5°C for 60 minutes

Today over coffee and a slow-cooked egg, I’ll introduce myself a little better…

In our house, it is a frequent struggle to find the store-cupboard ingredients used in world cuisines and professional kitchens, especially in small enough quantities for home use.  Even more challenging is finding interesting cookware: available only through friends on their travels abroad; or through professional suppliers that confusingly list the best quality at equal ranking alongside the worst.  For many years, I wished someone else would set up a website to help me: a one-stop-shop for everything a chef should have in their kitchen.  They never did; so I recently left a career in the City to do so.   The site, www.souschef.co.uk, launched in early summer.

I share this, because last week heralded the trialling of some of the sous-vide machines that we stock. Fittingly for the question of ‘chicken or egg’, it started with an egg.

A little background on eggs.  The white of an contains a number of different proteins, which coagulate at different temperatures: starting to thicken around 63°C, yet completely firm at 80°C.  The yolk sets between 65°C-70°C.

An egg comes with it’s own protective sous-vide packaging, so no need to vacuum wrap, unless you’re concerned about it cracking.  When cooked you can still ‘crack’ it from it’s shell, like a soft poached egg.  Watch the video at least twice.  Magic!

Thomas Keller who wrote the most highly regarded book published in English on sous-vide cookery, recommends  62.5°C for 45 to 75 minutes.  For his taste, he suggests 60 minutes, which I followed to the T.  David Chang in his Momofuku recipe book suggests 60°C to 63°C but for 40-45 mins.

The 62.5°C egg 

At Thomas Keller’s insistence, this egg was cooked for 60 minutes.

On cutting into the yolk, the texture is a little more viscous than a traditional soft-poached egg.  I loved the slight thickening, but the white – as you can see – is still translucent, and not yet set.

The 64°C degree egg

In spite of being a little above the temperature range suggested by Chang and Keller, 64°C is the cooking temperature more frequently cited by bloggers and sous-vide forum-users (yes, I do hang about these places..).  If this really were the perfect temperature, best not to ruin it by getting timings wrong.

After 45 minutes, the white is again translucent and breaks apart easily.  The yolk runs, but with a similar viscosity to runny honey at room temperature.  Note: the eggs I used had a wide variation in yolk colours, so not down to the cooking!

45 minute 64 degree egg

After 60 minutes, the white is better set.  The yolk is thicker, but unctuous.  It yielded my preferred yolk.

60-min-64-degree-egg

After 75 minutes, when the egg is cracked open, coagulated white starts to stick to the inside of the shell, however it is still not fully set.  The yolk looks very similar to earlier eggs, but barely moves when cut into.  It retains the indent of fork prongs for about 10 seconds.

75-min-64-degree-egg

The 68°C degree egg

At the two previous temperatures, the white was a little translucent and – for want of a better word – gloopy.  However, the yolk also started to thicken.  At 68°C for 60 minutes, the white is still runny, though you can see more clearly the definition between proteins that have set and proteins that haven’t: a raw liquid outer coating, and a fully set casing of white around the central yolk.  The yolk can be lifted away cleanly.

The solid yolk bears witness to the science that egg yolks solidify at 68°C.  The texture is waxy and malleable, like a recently cooled candle, or very sticky unsalted butter.  With none of the powderiness you’d observe in a hard-boiled egg, and the same consistency throughout, the texture intrigues.

So are sous-vide eggs the Emperor’s new clothes?  There is some excellent research and discussion in this article; far outstripping the science of my experiment.  Martin Lersch refers to the sous vide egg as an “inverted” or “inside out” egg: with a hard yolk, and a runny white.

Keller’s egg was closest to what is widely discussed in cheffy circles as the pinnacle of precision egg cookery: “an egg where the white is the same texture as the yolk”.  We were just not convinced by its merits.

I suspect there is a Western cultural bias in my samplers’ views; put off – rather than excited – by unfamiliar textures.  Upon serving guests an egg-white with ‘a super silken and tofu-like texture’ – so elegantly described in this post about onsen tamago (Japanese hot spring eggs) – the eggs were carefully pushed aside, with comments about timings.  Perhaps the silky texture has more place in a broth, or on a bowl of rice, than with English toast for an English breakfast.

Would love to hear your thoughts.  Have you tried slow-cooked eggs?  What do you with them?  What is the your ideal temperature/cooking time?

By way of an endnote, even the least adventurous Westerner will find sous-vide meat wonderful.  To enthuse you about the possibilities, I gratuitously present a photograph of a sous-vide venison fillet dinner (56C, 60mins), on a bed of salsify & celeriac mash, and some wilted spinach.  Tuck in!

All the food in this article was cooked using a SousVide water bath