Tempering Ingredients

So, I've heard lots and lots of chefs/people talk about getting things up to temperature. However, often the recommendations seem counter-intuitive. The following cases in particular, are ones I don't quite get:

1. Whipping Egg Whites: You are always told to use room temperature egg whites for making meringues and whipping the whites in general, with the oft cited reason that they somehow whip better once brought to room temperature. I would have thought that cold egg whites would get whipped up better since gases are more soluble in cold liquids.

The reasoning (on the part of the chefs) I can think off is that perhaps bringing up to room temperature is to decrease the temperature differential that would be introduced during cooking. The greater the temperature differential, the more rapid the expansion of the gas, which may lead to various problems.

2. Searing Proteins: Often you are told that before cooking/searing any animal protein in a pan, it should be brought up to room temperature first and then seared as otherwise the meat gets shocked somehow. I suppose this is again a reference to the temperature differential.

However, I would have thought that having a colder piece of meat would allow one to get a harder sear on the outside as it would take more time for the food to reach the right internal temperature allowing for a deeper, more delicious crust.

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Comments

Brandon_Byrd_40557

I don't think the issue with egg whites has to do with solubility. When you're making an egg white foam, you're basically folding air into a mixture rather than dissolving gas into it. As for what temperature is best, I've heard conflicting things about this (including that cold whites work better) and haven't come across anyone who has done a side-by-side test.

As for searing, I've never heard anything about shocking before. The conventional wisdom held that you should let meat warm up at room temperature before cooking because the interior will be undercooked if it comes straight out of the fridge. That's false and this is an unnecessary step. As you say, colder meat is better if what you want is a good crust without an overcooked interior. The "flip it every 10 seconds" technique also helps there.

brian_martin2001

1. When making meringue, you're not dissolving the airing whites, you're creating a foam where the air is trapped in bubbles of egg white.

2. According to where? I'vebeen heard of this either and I'd like to see the source. Quite the contrary, I've seen the opposite. It's recommended to take the meat right or of the refrigerator and put it o.j. the screaming hot pan to avoid potentially over cooking.

fisher23

For egg whites I think it depends on the results you are trying to achieve. From what I understand, cold eggs used to make a foam, the foam is slightly more stable and the bubbles formed are of a smaller size. This is what you want for a dried meringue like a pavlova. Room temperature egg whites produce slightly more volume as the air bubbles are slightly larger. All this has to do with viscosity of the cold egg as compared to the warmer egg. It would be interesting to compare a cold egg white foam to a SV 137°F pasturize egg white foam, my instincts tell me I would get more volume with larger air bubbles. From what I have read, if you are adding eggs or egg whites as an ingredient into fats, i.e. creamed butter, it is recommend they be at room temperature so that the fat doesn't solidify or break emulsion. So if your going to fold the egg whites in to other ingredients where the egg whites are used to lighten the texture or used as leavening it probably really doesn't matter whether you use cold or room temperature eggs. Of course then there is the variable of using fresh or old eggs, again this has to do with what you are trying to achieve. My understanding is that for the most stable egg white foam, the fresher and colder the egg whites the more stable the foam will be.

This and five bucks will get me coffee, maybe.

Amos_Schorr_168815

Re: 2, I usually see people saying to take it out of the fridge a half hour/hour in advance as it will promote more even cooking. Which is total BS, but it's that conventional wisdom that lots of people still believe, like how searing meat supposedly locks in juices.

Saad_94717

Yes indeed I should have been more careful with terminology. A meringue is indeed a foam and I was thinking of it as similar to a colloidal suspension, with the difference being that instead of suspended solid particles, you have suspended air bubbles.
However, I am not sure how the micro-structure differs from a solution. That is, if you zoom close enough, the structure of a an air-egg white solution and an air-egg white foam would be the same. The reason for different classifications is the macro-structure. Consequently, when referring to the microscopic details, I don't see any distinction between the two. Please correct me if I am wrong.

I suppose the steak tempering issue is resolved. I am reasonably certain based on your and other folk' comments that the whole tempering a steak thing is unreasonable. Anyone with a counter-argument is welcome.

Saad_94717

1. Yes, please see my explanation and eventual question below. In any case, at cooler temperatures the foam should be more stable since the air bubbles are less thermally active. However, I am not how much of a difference a 20C change (in going from a 5C fridge to a 25C room) would make. Please let me know your thoughts on this. Also, what do you think about this whole story with temperature differentials which should be important when the meringue is cooked in the oven?

2. I believe @Amos already addressed it.

brian_martin2001

I did read your assumption below. From it, i get the impression that you think a gas dissolved in a liquid is a microscopic foam. The problem with this is a dissolved gas is not an emulsion, it's suspension. Think soda pop before you open the lid. When you take water From the tap, there is gas dissolved in it. There is gas dissolved in most water the world over. If it was a microscopic emulsion, i.e. foam, things would have an extremely difficult time floating on water. This is no different than the egg white. There probably are gasses already dissolved in the white, but You don't crack open an egg and get a foam. The premise that egg whites on the microscopic level is the same as a meringue foam on the macroscopic level is flawed.

There will most likely be a difference in the texture of the meringue when using warm to cold egg whites, but this had nothing to do with the ability of gas to dissolve in the egg white. It gas to do with the ability of the proteins in the egg whitebetting able to form a temporary stable matrix around the air.

"Also, what do you think about this whole story with temperature differentials which should be important when the meringue is cooked in the oven?"

I have no idea what you're talking about.

Saad_94717

Of course not. I didn't insist on a meringue being a solution. I was simply trying to keep the terminology simple (albeit imprecise).

I think I did highlight the fact that a solution and a foam are different, as are emulsions and suspensions. However, often the difference are apparent macroscopically, and not microscopically.

I understand how foams and solutions are different from a macroscopic perspective. However, what I was uncertain about was whether there were discernible differences from a microscopic perspective. Try looking at microscopic images of foams and solutions (even suspensions and emulsions) side by side. Where as in a microscopic image of a solution you will see a liquid with the solvent particles interspersed, a foam's microscopic image seems quite similar, with gas bubbles interspersed in a liquid. Please do explain how at a microscopic level (100 nm - 100 µm) emulsions, suspensions, foams and solutions are different.

With reference to temperature differentials, please read my original post carefully.