Like most chemists, I like to cook. After all, what is cooking but the appropriate mixing of chemicals? In the lab we use flasks and beakers, but how do we equip our kitchen? Tiffany's in New York offers a silver frying pan for thousands of dollars, specialty stores sell gleaming copper pots for a couple of hundred, while a thin aluminum pot can be had most anywhere for a few dollars. What's the difference?
A gourmet cook will describe with a trembling voice how hot spots on the bottom of a pot can destroy the most delicate sauce. Efficient heat conduction and precise heat control are needed to avert this tragedy. Silver fits the bill in an ideal fashion but of course is very expensive. Copper conducts heat almost as well, however it can dissolve in food and cause nausea, vomiting and diarrhea. That鈥檚 why copper cookware is usually lined with tin or stainless steel to avoid such problems. This lining eventually wears off and requires replacement. There are also aluminum or steel pans with a thin layer of copper on the bottom, but this amount of copper is not enough to improve the heat conduction of the pan.
Aluminum itself is an excellent conductor. In fact, more aluminum cookware is sold than any other type. But some cooks have discarded their aluminum pots and pans because of reports linking aluminum with Alzheimer's disease despite there being no corroborating evidence for such a link. In any case, most such cookware is coated with a non-stick finish but even if someone were to use uncoated aluminum for all their cooking and for all their food storage, they would ingest only about 3.5 milligrams of the metal every day from this source. Compare that with the roughly 20 milligrams which is consumed daily as a natural component of food, or to the 1000 milligrams found in a daily dose of an antacid for an upset stomach. A single buffered pain reliever contains more than 10 milligrams of aluminum.聽聽
"Anodized aluminum" minimizes any leaching concerns. It is usually gray, harder than stainless steel, conducts heat better and is eternally nonstick, scratch resistant and easy to clean. The process of "anodizing" involves passing the aluminum through a series of electrochemical baths which cause the formation of a hard layer of unreactive aluminum oxide on the surface.
The traditional nonstick coating has of course been polytetrafluoroethylene (PTFE), better known as 鈥淭eflon,鈥� discovered accidentally in 1938. Recently it has been vilified because of its connection to PFOA, a chemical that was used in the manufacturing process but was never in the finished product. PFOA has been epidemiologically linked with kidney and testicular cancer as well as immunological problems around the DuPont plant in Parkersburg, West Virginia where it was used in the production of Teflon with waste material being improperly disposed. Since PFOA did not appear in the final product there was no issue with using Teflon cookware except when it was accidentally left on a stove and heated to an extremely high temperature when it can give off fumes that are toxic to birds. Teflon is actually an inert polymer that does not leach into food. While PFOA is no longer used, other small fluorinated compounds, termed "forever chemicals" because of their environmental persistence, are used in manufacture and can wind up in the environment. That being said, as far as performance goes, Teflon cookware as produced today has the best non-stick properties, meaning that food is not likely to burn, and burned food produces a variety of carcinogens. I have no issue with using Teflon cookware.
Just as Teflon cookware connotes modern times, cast iron symbolizes traditional cooking. It is great for grilling but is heavy and needs to be "seasoned" to prevent rusting and food adherence. This is done by coating the pan with a thin layer of oil and then heating it. The oil reacts with oxygen to form a tough, smooth, impervious layer. Carbon steel is lighter, functions like cast iron but also needs seasoning. Both cast iron and carbon steel are good conductors of heat and since small amounts of iron dissolve in food cooked in them, they even serve as a dietary source of iron, one of the few nutrients in short supply in the North American diet.
Stainless steel is made by alloying iron with other metals, most notably nickel and chromium. It is durable and does not tarnish but its heat conduction in general is not even and therefore most stainless-steel cookware is made with aluminum or copper bottoms. Some nickel may leach into acidic foods like tomato sauce and may present a problem especially to people with nickel allergies. Chromium is not a concern because most of us could probably use a little more of this mineral in our diet.
To minimize leaching, steel can be coated with porcelain to give 鈥渆nameled鈥� cookware. Such a ceramic finish has very good non-stick properties although not as good as Teflon. There is no safety issue with ceramics, which chemically are similar to glass and are essentially inert, although ceramic cookware tends to chip after a while. Silicones are fine for cookie sheets because they also have good non-stick properties but some cheap silicones may smell of processing chemicals so I would only buy high quality silicone items.
So, what is the best cookware? That depends on one's personal preference and pocketbook. Trained French chefs worship copper. But for us ordinary kitchen chemists, a stainless-steel pot with a thick aluminum bottom can serve just fine. Anodized aluminum is also very good. It has excellent non-stick properties, resists scratching and is easily cleaned. For frying eggs, Teflon is great. Nothing sticks to it and requires virtually no cleaning.聽
As far as leaching from cookware, my view is that when one considers the millions of chemicals, natural and synthetic, to which we are regularly exposed, any contribution made by those leaching out of cookware is insignificant. Bon Appetit!
