Aluminum foil is a basic object in any kitchen and one of the most versatile. Despite its thin layer of just a few millimeters thick, this material provides us with protection against light, oxygen, humidity and germs. Something not insignificant for this thin paper that acts as an absolute barrier and helps us prolong the useful life of food.
However, despite its versatility, certain doubts arise about its use. For example, we may have heard that cooking at high temperatures can transfer chemicals present in paper to food. What is true in that? Can we cook with aluminum foil? What precautions should we take?
How much aluminum is too much
This thin, shiny sheet has different functions, although most of the time we use it as a wrapper or for cooking. Most of the time what we do is take advantage of one of its most notable characteristics: it is an excellent conductor of heat, which means that heat and humidity do not escape from the wrapped foods and, in addition, it is very malleable, which which allows us to use it in an infinite and variety of foods of different shapes and sizes – although here we will see some nuances. We can also use it as a bottom liner for baking trays and prevent food from sticking.
The European Food Safety Authority (EFSA) determines that ingesting one milligram of aluminum per kilo of body weight through food per week is safe. This means that, in an adult person weighing about 70 kilos, the aluminum limit is 70 milligrams per week. According to the World Health Organization (WHO) and the Food and Drug Administration (FDA), aluminum levels below two milligrams per kilogram of body weight per week are not likely to cause health problems. What’s more, we probably don’t consume enough to pose a health risk, since it is estimated that only 0.1% of ingested aluminum is absorbed in the intestinal tract and becomes bioavailable.
Water and certain foods, such as bread, farinaceous products, some vegetables such as spinach and chard, as well as organ meats, seafood, coconut, spices, tea and herbal teas are some of the foods that contain higher concentrations of aluminum (between 5 and 10 mg/kg). The question that arises here is whether we are consuming too much aluminum and whether we can be exposed to high levels through the migration of aluminum foil into food. An issue that arises and may cause concern when considering aluminum as a heavy metal that, unlike other substances, can have effects on the body if large quantities accumulate.
Precautions when using aluminum foil in contact with food
Although some research has shown that aluminum present in kitchen utensils, containers or paper can migrate the metal into food, it is important to know how much we ingest if we use this paper. As the Catalan Food Safety Agency (ACSA) warns, the migration of aluminum in food is “unimportant under normal conditions.”
Aluminum is only a problem when added to total consumption, although some EFSA evidence suggests that total aluminum consumption is lower than we usually think, meaning that even if we ingest a little of this metal through paper aluminum, should not pose a risk.
However, there are some circumstances that force us to be a little more cautious, such as if foods are acidic, such as tomato sauce or applesauce, or if we cook at very high temperatures.
And, although aluminum foil itself is not dangerous to health, as a precaution, and as established by a European Council study on metals and their use in contact with food, we should not grill highly acidic foods. or with a lot of salt in aluminum foil, since the acid or salt from cut apples, for example, can release aluminum ions from the paper and these can migrate into the food.
It is also not advisable to use metal or aluminum material containers such as pots, trays or casseroles to heat, cook or store hot foods with high acidity content, such as fruits and vegetables, because aluminum is soluble in acidic pH at high temperatures. Therefore, the recommendation would be to avoid, as far as possible, wrapping acidic foods with aluminum foil and replacing it with film plastic.
A risk assessment published in the International Journal of Electrochemical Science a few years ago identified some key factors that can increase the amount of aluminum that can leach into food. And he listed four:
- Cook at high temperatures
- Use aluminum foil when cooking highly acidic foods, such as tomatoes or lemons
- Cooking with aluminum utensils and aluminum plates or baking dishes
- Use aluminum foil
Despite everything, the European Food Safety Authority (EFSA) has confirmed on occasion that the quantities that can migrate are insignificant, almost negligible, around 0.1 mg/day, very far from the milligram that it considers safe.
In general, foods that are less acidic, less salty, and contain less liquid tend to absorb lower amounts of aluminum. However, meat or fish marinated with lemon tends to absorb more during cooking with aluminum foil.
So is it safe to cook with aluminum foil? According to this study published in Food Science & Nutrition, it can be safely used up to 200ºC in the oven and for grilling with direct heat. The research results suggest that foods baked in aluminum foil at temperatures of about 160ºC have less aluminum loss compared to those baked at higher temperatures (above 220ºC).
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