Will dry frying salt do anything?
June 13, 2016 5:23 PM   Subscribe

This recipe recommends dry frying salt "at low heat for about 10 minutes until it turn a brownish color". Would this actually change the salt at all?

As far as I understand it, salt on its own isn't going to react in any way at the sort of temperatures you get on a stove. Is it possible that given some temperature distribution the salt might react with the atmosphere or leftover residue in the pan?

I've never seen another recipe suggest frying or toasting salt like this, and I can confirm it's a delicious recipe despite skipping the step, but the recent caramel sugar thread has left me doubting my cooking chemistry convictions.
posted by lucidium to Food & Drink (14 answers total) 4 users marked this as a favorite
Salt doesn't melt until ~1,500°F, which you can't achieve on your stove. Further, salt has neither the amino acids nor sugar to cause the Maillard reaction to occur. In short, you are correct; for the temperatures a stove can achieve, salt will not react in any way. It's essentially the only spice you have that can't burn.

In the recipe stated, the salt itself isn't reacting to the heat; it's simply picking up anything that has been previously burnt and/or polymerized onto the pan.
posted by saeculorum at 5:46 PM on June 13, 2016 [5 favorites]

It's a great way to pit an expensive stainless steel pan. All-Clad voids their guarantee for salt pitting and recommends only adding salt once food is in it boiling.
posted by cecic at 5:47 PM on June 13, 2016 [3 favorites]

In theory it just dries it out. If there were any impurities in your salt, it would cook them, but if you're using pure NaCl, it's just the drying of any water it's absorbed. Sounds pretentious to me.
posted by taff at 5:47 PM on June 13, 2016 [3 favorites]

the recipe assumes you're using a (seasoned, steel) wok. so i guess it's picking up the gubbins from the surface.

does it turn brown if you don't stir it? if it does, that suggests something odd is happening. all i can think of is that some additive (iodine? anti-caking agent?) is oxidising.
posted by andrewcooke at 6:07 PM on June 13, 2016

The fact of calling it dry frying suggests to me that it's not trying to say the salt is what's being cooked, but salt is the medium for the heat to toast the other ingredients.

Take a look at the first 30 seconds (or however much you need) of this video. It's a man (in Chhattisgarh, India, apparently) making puffed rice (i.e. rice krispies-- though he's using brown rice). He has a very hot pan (kadhai) full of very hot black sand, and the sand is holding and then delivers the heat directly to the rice, the way cooking oilwould. After the rice pops from the intense heat of the sand, he sifts the sand back out, and voila, potentially gritty street food.

Frying in oil is considered "dry" inasmuch as it's not "wet" i.e. water based, but it's obviously still a liquid. This is dryer-than-dry cooking, and while, as described above, it may do damage to your pans, it's a pretty cool technique to experiment with. Probably more familiar in the west in the form of salt-dome roasting, that kind of thing. Is it "frying"?" Eh, I can see what they're getting at, but I'd call it toasting. Anyway, you couldn't really sift the salt back out in your application, so it's just as well you can eat it. All in all, this is toasting, and you don't need salt to do toasting.

TL; DR: The salt is the message and the medium. I'd say just toast the spices in the usual fashion rather than doing this step.
posted by Sunburnt at 6:08 PM on June 13, 2016 [4 favorites]

Sunburnt, I thought the recipe would do something similar and use the hot salt to cook the other ingredients but it says to let the salt cool before mixing with the other ingredients.
posted by any portmanteau in a storm at 6:13 PM on June 13, 2016

okay, as I reread this, it does seem like the salt is cooked by itself.

Well, I guess the best thing to do would be to try it and see how what it does and how it tastes differently. Cheap experiment, assuming it doesn't destroy the pan in one go, which it really shouldn't as long as you're not using non-stick (which will let the heat destroy its coating if allowed, salt or no salt).
posted by Sunburnt at 6:46 PM on June 13, 2016

The only chemical reaction I can think of here would be that some of the chlorine cooked off and the sodium had a reaction with atmospheric oxygen or atmospheric water vapor. The result would be sodium oxide or sodium hydroxide, neither of which would you really want in your food in significant quantity. (In trace amounts it wouldn't make any difference.)

But it wouldn't turn brown. Sodium oxide and sodium hydroxide are both white. And "low heat" wouldn't do this at all.
posted by Chocolate Pickle at 7:57 PM on June 13, 2016

The recipe calls for using a wok; could it be that 10 minutes in a well-seasoned wok would add color and flavor directly to the salt, without it actually changing color per se?
posted by current resident at 8:02 PM on June 13, 2016

It won't destroy your pan, so go forth and cook! The pitting is superficial. It would void the warranty against people who want their cookware to remain unblemished and would try to claim a defect because of the (not even very noticeable) pitting that occurs when you put salt into not-boiling water and it sinks to the bottom instead of dissolving before sinking.

I don't even know if it would pit the pan if it's dry versus when you're bringing water up to boil, but either way, no biggie.
posted by the thorn bushes have roses at 8:15 PM on June 13, 2016

The only chemical reaction I can think of here would be that some of the chlorine cooked off and the sodium had a reaction with atmospheric oxygen or atmospheric water vapor.

This would occur if the entropy increase from dissociating salt into its sodium and chlorine constituents were sufficiently large to counteract its (very strong ionic) bonds. A very rough calculation using the entropy and enthalpy of formation of NaCl yields 4,300°C; in any case, the salt will melt first at 800°C. So as you note, no "cooking off" of the chlorine would ever occur in anyone's kitchen.
posted by Mapes at 9:24 AM on June 14, 2016

Ah, the recipe is apparently confused; salt & pepper wings without the pepper. (Why?!)

It's quite common in Cantonese/Souther Chinese cooking to "dry fry" salt and ground white pepper together (sometimes with other spices); some of the oils and other aromatics are driven off from the pepper granules (and some of them presumably undergo a chemical reaction) and combines with the salt. It's a much more flavourful dip/"dry rub" than salt alone or salt simply mixed with white pepper.

It's good as a dry dip with Peking duck and dry roasted chicken too.

I suspect that if you dry fry white pepper alone it scorches more easily than if fried mixed with salt - and the oils/volatiles get stuck to the pan/wok/evaporate-off instead combining with the salt.

Salt alone shouldn't change colour after mild heating. Unless it's Chinese salt and it's adultered with who-knows-what*.

*am Cantonese, most of my extended family lives in HK and no longer consume any food exports from the mainland and have even stopped visiting if they can help it
posted by porpoise at 2:17 PM on June 14, 2016 [1 favorite]

It's the seasoned wok. I have several recipes that call for this, or for a little oil and then frying the salt in the oil directly before adding other ingredients. It probably doesn't make much flavor difference but might help soak up some of that great wok-cooked flavor.
posted by Lady Li at 6:07 PM on June 14, 2016

Oh, if the rest of the ingredients aren't cooked directly on the wok then the salt is the only source of "wok flavor"! So yes that's why.
posted by Lady Li at 6:09 PM on June 14, 2016

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