So, I was telling a friend how I wrap my sweet potatoes in aluminum foil before I put them in the oven. Why do I do this? Because that's how I've always seen my mother do it. I never really thought about it and the sweet potatoes come out so nice and juicy.
Anyhow, my was telling me that the aluminum leaches into the food when you cook with it like that? I didn't think so....Am I wrong?
Unlikely to be a problem with sweet potatoes. Aluminum leaches out with acid, and sweet potatoes aren't acidic. Contact is another factor. If you're baking whole sweet potatoes in the skin, wrapping with aluminum foil and not eating the skin, the risk of leached aluminum is zero, probably more aluminum naturally occurring in the sweet potato than is added via the foil.
See also: http://paleohacks.com/questions/56639/do-you-cook-using-aluminum-foil-pans Split evenly between folks fretting over it and not giving it second thought.
Agree with Matt above, but I don't like to use foil because it seems so environmentally unfriendly. I actually pierce my sweet potatoes and zap them in the microwave. Three minutes on a side is much quicker than cooking in oven.
You can place potatoes right on the oven rack wrapped in absolutely nothing. They come out just fine.
Also agree about the acidity issue. If you've ever covered a dish of ziti or lasagna (in your pre-Paleo days) with aluminum foil, you may have seen it literally eroded away where it came in contact with the tomato sauce. Yikes! I think it's okay to wrap more "plain" stuff in for the fridge.
I agree that the risk of aluminum leaching is very minimal, especially if you don't eat the skin. As to cooking method, I think the difference between wrapping them in foil and putting them directly on the rack (pierced a few times so they don't explode) is that wrapping them in foil would technically steam the potatos as opposed to baking them. In end product you would end up with softer skin with steamed, and crispier with baked.
So what's better when it comes to cooking steak? Using a cast iron frying pan (frying isn't too good?) vs. broiling in an electric oven with an aluminium foil covered oven tray? Beef is quite acidic and I see beef juice and tallow actually boiling on the foil at 300F.