A lot of people have asked me this question and to be honest I wasn’t sure of the answer. Having a sister who is a chef wasn’t at all helpful either, but we do have an answer from the foil folks.
When cooking tomatoes with foil, does the foil discoloring or mildly becoming holed create anything unsafe with the food?
The answer, according to the Alcoa folks, is no it isn’t an issue.
From Alcoa:
Why does my foil darken or discolor sometimes during baking?
The darkening of foil may be caused by moisture from the food being covered. This results in a buildup of aluminum oxide. This is a totally harmless substance that is naturally present on the surface of foil. Moisture tends to accelerate this buildup.
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.
bem
February 2, 2011
The problem with this post is that the only source of knowledge used is a company that profits off the sale of aluminum. Not that what they say is completely invalid, but they do have a conflict of interest when talking about safety. I know you said it was hard to find an answer, but I just thought might be good to at least mention that explanation is a little one sided.
I hope this isn’t an ancient post I’m replying to.
May 16, 2011
When food comes in contact with aluminum foil, does aluminum contaminate the food? In other words, can one get unsafe amounts of aluminum in food from using aluminum foil?