Appliance Science Experiments: In search of the perfect scrambled egg

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Poets and philosophers may argue about the meaning of life, but some of us are more concerned with important things, like how to make perfect scrambled eggs. I've been struggling with this problem of physics for years, looking for the right balance of texture (firm, but not rubbery) and taste (strongly eggy, with a hint of pepper) for my lunch. Recently, I've been experimenting with sous vide as a way to make these, and I thought I'd share this with you. The results, that is; not my lunch.

Sous vide is a new way of cooking, where a device carefully regulates the temperature of water, cooking the food (sealed in a bag) much more precisely than other methods. I discussed it in more detail in a recent column. This more precise control means that it can fulfill the main requirement of any scientific experiment: controlled conditions. By using the same recipe and cooking time, but varying the temperature of the water bath, I could see what effect the cooking temperature had on the final dish.

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To test this, I used an Anova Precision Cooker fitted to a large saucepan (we reviewed this product previously ). I used two eggs (all from the same batch purchased at the same time), carefully whisked until blended with a pinch of salt and pepper and a teaspoon of 2 percent milk. I then put this mix into a sous-vide bag and removed the air by pushing it out and sealing the bag (I didn't use the vacuum pump method: with liquids like this, you don't need it). I cooked the mix for 30 minutes, with a bit of gentle massage every 10 minutes to make sure that the mix didn't get lumpy. I then removed the resulting scramble and tested it (as in, photographed, examined and eaten). I tested a range of temperatures, starting at 140 degrees Fahrenheit (60 degrees Celsius) and going up to 170 degrees F (77 degrees C).

For me, the perfect texture of scrambled egg is a semisolid mix, with a texture between liquid and solid. It should be liquid enough to pour, but solid enough to retain its shape on a nicely browned bit of toast. This platonic ideal of scramble is hard to find: my attempts cooking with other methods vary from gloppy liquids to the rubbery, dry overcooked solid that you get in a bad truck stop.

My research revealed that the range of temperatures to look at was between 140 degrees F (60 degrees C) and 170 degrees F (76 degrees C), as this range of temperatures is where the white and yolks of eggs start to solidify. Below 140 degrees F, both remain liquid. Above 170 degrees F, both are quickly solidified, so we are looking for somewhere between the two. Serious Eats has an excellent guide to how whole eggs cook in sous vide that shows how the temperatures affect the white and yolk differently. For this experiment, I am looking at the combination.

Let's do lunch

I discovered a few things from this experiment. The first is that I like scrambled eggs for lunch, but that eating the same thing every day gets kind of repetitive. The second is that small variations in temperature can make a big difference to the taste and texture of the scrambled eggs.

I started at a temperature of 140°F (60°C). After cooking for 30 minutes, the eggs still had a very runny, almost completely liquid and uncooked texture. The mix had started to coalesce, but there were only small, isolated solid lumps in there. I didn't bother tasting it: I was after scrambled eggs, not egg soup.

Upping the temperature to 150 degrees F (about 65 degrees C), I found that the texture improved, with more of the mix coalescing, especially the white, which showed up as small white lumps in the mix. That's because the whites of an egg solidify at a slightly lower temperature than the yolk, which is how you get soft-boiled eggs with solid whites, but liquid yolks. But, for me, this gloop isn't solid enough: it's still way too liquid to be called a scramble.

Next, I turned up the heat to 160 degrees F (about 71 degrees C). This extra 10 degrees F (about 6 degrees C) made a considerable difference: the texture was much more solid, and the resulting scramble had the sweetness and rich taste that egg yolks develop as they are cooked. The consistency was great, with a smooth, custardlike texture and consistency.

Because it's getting more solid, I upped the temperature by just 5 degrees next. Cooking at 165 degrees F (about 73 degrees C) produced a scramble that was more set, with a slightly oily sheen on the surface and the liquid texture that a good scramble should have. The taste was also great, with more of the richness that cooked yolk has that gives scrambled eggs their flavor. Have I hit the sweet spot? Perhaps, but let's keep going...

Another pass at 170 degrees F (about 76 degrees C) produced a scramble that was even more solid. Too solid for me; it couldn't be poured. Instead, I had to spoon it out in lumps, and it didn't have the slightly liquid mouth feel that makes scrambled eggs so appealing. That might have been acceptable if the rich taste was enhanced by the higher temperature, but it was not: the rich, complex taste wasn't any more developed than the 165-degree mix.

The results are in (my belly)

I'm going to go with 160 degrees F as being the optimal temperature for me. I like my eggs to be somewhere between liquid and solid, but a little more toward the liquid end of the spectrum. That's an individual preference, though, and many people favor the more solid scramble that you get from microwaving. For that, the higher temperature would be better: 165 degrees F produced a more solid scramble that holds together well.

The joy of sous vide is that you can produce this sort of differentiation. While a chef might train for years to learn how to cook like this without a precise temperature controller at his or her side, a sous-vide setup puts it just a few button presses away . And it does it with the consistency that no chef can match: it doesn't have bad days or get distracted. This level of control is where sous vide excels, and, to me, is what cooking is all about: finding the sweet spot that produces your own personal preference for dishes, rather than what the experts tell you. Now, if you'll excuse me, it's time for lunch, and I have a craving for some eggs. Scrambled, please....

Safety note

One thing to note here: I had several comments about the safety of sous vide cooking on my previous column. The US government requires all eggs used in commercial foods be pasteurized (meaning they are heated until most bacteria are killed) by putting them into water at 138 degrees F for 3 minutes. All of the tests I did above are well above this temperature. So, even if the 140-degree scramble I made above wasn't very tasty, it was still safe.