Aluminum foil and acid or salt

[JAZ]

I use a lot of aluminum foil in the kitchen -- both to cook with and to store leftovers (mostly meat). I've always thought it's a bad idea to use it with ingredients that are high in acid or salt, that they would damage or even dissolve the foil (like the way foil on top of meatloaf will dissolve if it's sitting on top of a ketchup glaze.)

Lately I've run across several recipes that call for using foil with foods that are high in acid, or salt, or both. For instance, one is a gravlax recipe that calls for wrapping the very heavily salted salmon in foil. The only time I made gravlax, I thought I remembered the recipe specifically calling for plastic wrap, not foil because the foil would react with the salt. The others were recipes that used foil to braise dishes that called for pretty acidic braising liquids (orange juice in one case; wine in another).

Was I wrong about aluminum foil? Are these applications safe?

[Paul Bacino]

Braising, I would rather use parchment..

I just cut around the lid and insert into the vessel works great, these are of course are above the liquid braise!!

But I know a few recipes for ribs that are wrapped in foil, with tomato base and they seem just fine!! Could be the low and slow temps though.

BestPB

Edited September 28, 2011 by Paul Bacino (log)

[andiesenji]

I've never heard of using foil on gravlax. Before the advent of plastic wrap, one used waxed paper and sealed it with aluminum foil as the outer wrap.

Ages ago the fish was salted and buried in sand just at the edge of the tideline so it would be wetted (and thus cooled) twice a day.

I have seen fairly old recipes that use wet "white" clay to seal the fish after salting.

[Country]

Ages ago the fish was salted and buried in sand just at the edge of the tideline so it would be wetted (and thus cooled) twice a day.

What kept sea gulls, shags, and all the other shore birds - and crabs - from digging it up and having a feast?

[andiesenji]

Ages ago the fish was salted and buried in sand just at the edge of the tideline so it would be wetted (and thus cooled) twice a day.

What kept sea gulls, shags, and all the other shore birds - and crabs - from digging it up and having a feast?

I have no idea but it was done this way for hundreds of years, possibly thousands.

[Norm Matthews]

When I smoke ribs, I put them in foil for part of the cooking time but they have not been sauced yet.. That is only done, if at all, at the very end. I think most other BBQers. do the same.

[qrn]

When I smoke ribs, I put them in foil for part of the cooking time but they have not been sauced yet.. That is only done, if at all, at the very end. I think most other BBQers. do the same.

Yes I do that as well,but after they are well cooked/smoked,then,wrap, and put them in a little counter top oven at 200 degF for a couple hours before serving ,really helps.

Bud

[Mikels]

Chemically, aluminum (Al) is a fairly reactive metal. When in contact with salt (NaCl), it is likely it will form AlCl3. In the presence of acids it will form different compounds, depending upon the acid.

[Country]

Ages ago the fish was salted and buried in sand just at the edge of the tideline so it would be wetted (and thus cooled) twice a day.

What kept sea gulls, shags, and all the other shore birds - and crabs - from digging it up and having a feast?

I have no idea but it was done this way for hundreds of years, possibly thousands.

Maybe the answer is in your link...

"The original version of the dish was made by fishermen who buried salmon above the high tide line after rubbing it in salt, sugar, and dill. While it was buried, the salmon fermented, and it became quite pungent and strongly flavored."

After that not even a hungry seagull would touch it.

[Kevin Liu]

Here's the answer from the Reynolds Website:

Why does aluminum foil sometimes melt and leave black specks on the food?

Occasionally when aluminum foil comes in contact with a different metal or a food that is highly salted or acidic, small pinholes are formed in the foil. This is a harmless reaction that does not affect the safety of the food. It is difficult to predict, but may occur under the following conditions:

1. When aluminum and a dissimilar metal are in contact in the presence of moisture, an electrolytic reaction may occur causing a breakdown of the aluminum. To avoid this use aluminum, glass, ceramic, plastic or paper containers. Do not cover sterling silver, silverplate, stainless steel or iron utensils with aluminum foil.

2. A similar reaction may occur when salt, vinegar, highly acidic foods or highly spiced foods come in contact with aluminum foil. The result of these reactions is a harmless aluminum salt. Some aluminum salts are used in medicines to treat stomach disorders. The food can be safely eaten; however, the aluminum salt particles can be removed from the food to improve the appearance of the food.

On the same page, they write:

...when using Reynolds Wrap® Release® Non-Stick Aluminum Foil. The non-stick coating is applied during manufacturing to the dull side of the foil. Always place the non-stick (dull) side toward the food.

I would say if you do have Non-Stick aluminum foil, use the dull side in contact with the food to reduce reaction as much as possible. Or wrap first in something nonreactive, before finishing with foil.

[Kouign Aman]

Even meat will react with the foil and get those little holes, if left in contact long enough. Protein = linked amino acids.

I've only seen it happen where the keelbone of the turkey is in contact with the foil for several days.

I think the folks who wrote those recipes didnt think it through.

[andiesenji]

Even meat will react with the foil and get those little holes, if left in contact long enough. Protein = linked amino acids.

I've only seen it happen where the keelbone of the turkey is in contact with the foil for several days.

I think the folks who wrote those recipes didnt think it through.

I think you are correct. I occasionally come across a recipe that has some less than stellar instructions and one gets the "what were they thinking?" flash.