Like most chemists, I like to cook.聽聽After all, what is cooking but the appropriate mixing of chemicals?聽聽In the lab we use flasks and beakers, but how do we equip our kitchen?聽聽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 almost anywhere for a few bucks.聽聽What's the difference?聽
A gourmet cook will describe with a trembling voice how hot spots on the bottom of a pot can destroy the most delicate sauce.聽聽Efficient heat conduction and precise heat control are needed to avert this tragedy.聽聽Silver fits the bill in an ideal fashion but of course, is very expensive.聽聽Copper conducts heat almost as well, however it can dissolve in food and cause nausea, vomiting and diarrhea.聽聽聽
Copper cookware is usually lined with tin or stainless steel to avoid such problems.聽聽This lining eventually wears off and requires replacement.聽聽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.聽
Aluminum itself is an excellent conductor.聽聽In fact, more aluminum cookware is sold than any other type.聽聽But some cooks have discarded their aluminum pots and pans because of reports linking aluminum with Alzheimer's disease.聽聽Most researchers today do not believe that aluminum is a causative factor in Alzheimer's and in any case, the casting away of the cookware is to no avail.聽聽聽
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.聽聽Compare this with the roughly 20 milligrams which are 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.聽聽A single buffered pain reliever contains more than 10 milligrams of aluminum.聽聽聽
To put our minds completely at ease, it may be a good idea to avoid cooking or storing highly acidic or salty foods in uncoated aluminum pots for long periods.聽聽Tomato sauce, rhubarb and sauerkraut would fall into this category.聽聽In fact, a good general rule is to store food in the refrigerator in glass containers and not in pots or pans.聽
Even though this represents no danger, aluminum pots will sometimes discolour as a result of reacting with food.聽聽Simmering for fifteen minutes with a solution made by dissolving a couple of spoons of cream of tartar in a litre of water usually restores the finish.聽聽聽
A new kind of aluminum cookware, made of "anodized aluminum"聽聽has recently been introduced.聽聽It is usually gray, harder than stainless steel, conducts heat better and is eternally nonstick, scratch-resistant and easy to clean.聽聽The process of "anodizing" involves passing the aluminum through a series of electrochemical baths which cause the formation of a hard layer of aluminum oxide on the surface.聽聽This layer is unreactive and does not leach aluminum into food.聽
The traditional nonstick coating has of course been Teflon, discovered accidentally in 1938.聽聽This inert substance does not react with food in any fashion.聽聽Words of comfort to anyone who has ever worried about swallowing bits of Teflon coating which may flake off older cookware!聽聽The perfluorocarbon resin passes through the body unchanged.聽
Teflon may release some toxic vapours if heated to high temperatures for long periods.聽聽While this represents little risk to humans, there have been isolated reports of pet birds being overcome by such kitchen fumes.聽聽聽
Just as Teflon cookware connotes modern times, cast iron symbolizes traditional cooking.聽聽This metal is a good conductor of heat and since small amounts dissolve in food, it even serves as a dietary source of iron, one of the few nutrients in short supply in the North American diet.聽聽聽
Cast iron cookware should be "seasoned" to prevent rusting and food adherence.聽聽This is done by coating the pan with a thin layer of oil and then heating it.聽聽The oil reacts with oxygen to form a tough, smooth, impervious layer.聽
Stainless steel is made by alloying iron with other metals, most notably nickel and chromium.聽聽It is durable and does not tarnish.聽聽The heat conduction, in general, is not even and therefore most stainless steel cookware is made with aluminum or copper bottoms.聽聽Some nickel may leach into acidic foods like applesauce and may present a problem especially to people with nickel allergies.聽聽Chromium is not a concern because most of us could probably use a little more of this mineral in our diet.聽
To minimize leaching, steel can be coated with porcelain to give enamelled cookware.聽聽The finish is stain and scratch-resistant and is perfectly safe.聽聽No lead is used in the manufacture of such glazes.聽聽Lead may be used in glazes destined for slow cooking such as "crock-pots," but the manufacturer has to provide evidence that no leaching of the metal occurs.聽聽The stories which make the rounds about lead poisoning from ceramic ware invariably involve improperly manufactured items.聽聽聽
A classic story is told about a California family which suffered acute lead poisoning from drinking orange juice stored in a ceramic pitcher purchased in Mexico.聽聽At first, no one was able to diagnose the condition.聽聽The doctors advised leaving the house just in case the problem was environmental.聽聽When the family left, the symptoms disappeared.聽聽When they returned to the house, the symptoms reappeared.聽聽This cycle repeated several times until they called in a chemist who immediately recognized the lead glaze on the pitcher in the refrigerator and solved the problem.聽聽Obviously, they should have consulted a chemist sooner.聽
So what is the best cookware?聽聽Of course, it depends on one's personal preference and pocketbook.聽聽Trained French chefs worship copper.聽聽But for us ordinary kitchen chemists, a stainless steel pan with a thick aluminum bottom can serve just fine.聽聽Anodized aluminum is also excellent.聽聽Nothing sticks to it, it cannot be scratched and requires virtually no cleaning.聽聽And as far as concerns about Alzheimer's disease go, I've been cooking in aluminum pots all my life and I can't remember any problems!
