Sunday, August 26, 2012

Why a copper pot for jam making


To begin with, copper is a mineral that occurs naturally in the human body. But the myths and mystique surrounding copper as a metal are many and imaginative. For instance, the metal has also been credited with curing arthritis. And many a tennis player attributes the alleviation of his elbow problems to wearing a pure copper bracelet on the opposite arm. But talk with an orthopedist and you're likely to hear that all that does is turn the braceleted wrist dark grayish black.

Copper cookware has its own share of long standing legends and some of them have a degree of truth to them. Some cooks are afraid to use it, regarding it as potentially "poisonous". Some are simply too lazy to give it the proper care. Some couldn't imagine making a sauce without it, or beating egg whites in anything other than an unlined copper bowl. Separating fact from fiction becomes challenging for the cook who isn't also a chemist.

What is Copper? 

Copper is strong but malleable and an outstanding conductor. Its conductive qualities are linked to molecular structure, which in the case of copper, is quite loose. With 29 protons in each copper molecule's nucleus, it contains one free-floating electron which easily conducts heat and electricity through the metal. Copper electric wires work well for the same reason copper pans do.

Copper is mined at great expense from deposits primarily found in South America. It is refined, melted into ingots -- and sold by the ton or pound. It comprises only .01 percent of the earth's crust by weight, and like all nonrenewable resources, its value increases continually. Its rarity, coupled with rising labor costs, leads experts to predict drastic price rises in the near future
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Is It Worth It? 

Copper, often praised as the ultimate culinary metal, has characteristics which make it very desirable for cooking. Because it is such a good heat conductor, heat is transferred from flame or coil throughout the pan base and up the sides. The even distribution of heat cooks foods uniformly near the top of the pot as well as at its bottom -- and it cooks them quickly so there is minimal drying of moist foods.

Copper cookware almost always compares favorably to other types of cookware. Stainless steel is not the best conductor, although its strength, durability and ease of cleaning make it a favorite among some cooks. A heavy-gauge aluminum bottom on a stainless steel pan will increase the pan's efficiency, but a thick-gauge aluminum pan is, overall, a better conductor. Aluminum, however, reacts to acidic foods by imparting a metallic taste and sometimes discoloring them -- egg whites beaten in aluminum, for instance, may turn gray. It also does not retain heat for long periods.

Cast iron is the favorite of many cooks and, although it does not heat extremely rapidly, it does heat very evenly with few hot spots. When well seasoned, iron cookware is easy to clean -- a distinct advantage over copper. Iron will rust, however, and must be thoroughly dried after cleaning.

Iron and aluminum with enamel coatings, glazed ceramics and porcelain cookware all are good for cooking but the upper portions (sides) of the utensils remain significantly cooler than the bottoms so heat distribution is uneven.

Serious cooks generally have an assortment of pans made of different metals, each designated for a specific purpose. Frequently, the copper pots are greatly valued by the cook, shined and displayed as prized possessions.

"Copper is the best cooking equipment you can have," claims Henri Boubee, the former executive chef of Windows on the World restaurant in New York City. "It heats uniformly, holds the heat best, and cooks the quickest." His opinion is shared by numerous cooks. The facts are correct but if you are going to spend what could be up to thousands of dollars on a full set of heavy-duty copper, you should be aware of the pitfalls and problems connected with buying and caring for it. Keep in mind too, that good cooking copper is extremely heavy. So, if you have weak wrists, think twice about copper, weight the piece in the store and then try to imagine it two or three times heavier when filled with hot food
Jam making

Rachel Saunders of the Blue Chair Fruit Company making jam, and behind her on the stove you can see one of these pots. I emailed her, asking about the pot, and wondering whether the fact that it’s unlined copper is a problem. She pinged me right back and said this: “Actually, these are THE classic pots for jam making. Once the fruit has been combined with sugar, it will not react with the copper — in fact, quite the opposite; it does not affect the flavor at all, unlike aluminum and various other metals, and it makes the cooking SO much easier. I can’t recommend it enough; the only thing to remember is, don’t put fruit by itself into a copper kettle, or it will react!” 
Making Copper Cookware 

Overall, the weight and lining of copper cookware are more important than its nationality. French copper is traditionally the highest in quality and remains the standard by which other copper is measured. A large proportion of French copper comes from a little town outside of Paris called Villedieu Les Poeles, where copper is made much as it was a century ago.

The molten copper is poured into molds, the copper bowl of the pot is properly weighted and heavy metal handles are riveted on by hand at a slight angle to the pot so that it is well balanced. Since so much hand work is involved -- the handles must be attached by hand for proper balance -- the cost is high. You will also see beaten, or hammered, copper on the market. As the name implies, it is copper that has been beaten with a hammer-like soft object so that it develops little indentations all through it. Some cooks claim that the tiny Indentations reinforce the copper and help the air and heat to circulate. Also, hammered copper doesn't show scratches as much as smooth surfaced copper does. But there will be less and less hammered copper on the market in years to come. It is difficult to hammer copper by machine (except for very large pieces) and though some copper is still hand-hammered, laws have been passed in many parts of France to eliminate hand-hammering, as it causes deafness among the workers.

Other countries manufacturing high caliber, heavy gauge copper are Canada, Germany, Chile and England. Portuguese copper is usually much thinner than French -- and inadequate for most uses. Korean copper can be both good and bad -- some of it a full one-eighth inch thick and as high in quality as any other. It's the thickness of the gauge and the balance of the handle that determines its suitability, not its country of origin.

Optimum Heat Conduction = Eighth Inch (2.5mm) Thick

The heavier the gauge, the better the heat distribution is. Gauge is simply the thickness of the metal and for copper should be one-eighth of an inch for optimum performance. A too thin layer of copper, such as is found coating the bottom of some stainless steel cookware, will not distribute heat as evenly as a solid copper pot since it hasn't the heft to hold and carry the heat sufficiently
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Lined and Unlined 

What copper is lined with is not the least important consideration. Only a few utensils made from copper are traditionally without a lining -- saucepans used for caramelizing sugar and bowls for beating egg whites generally are the only two unlined utensils available in this country. Copper is slightly acidic and reacts with certain foods and therefore usually is lined.

It is debatable whether the theory holds that egg whites beat to a significantly higher volume when whisked in a copper bowl. Dr. I. Herbert Scheinberg, professor at Albert Einstein College of Medicine in New York, thinks there is very little truth in it. "Let's just say that there is no chemical basis of which I am aware," he says. This position is hotly denied by Chef Henri Boubee, who insists chefs have been beating egg whites in copper for centuries for a very real reason: they have more volume than whites beaten in other materials. Author Howard Hillman (Kitchen Science, Houghton Mifflin Co., 1981) further says that when egg whites are beaten in unlined copper with a metal whisk, the copper emits an electrostatic force that reduces the energy and time usually needed for firm peaks.

The natural acidity in unlined copper causes egg whites to stabilize better. You never add cream of tartar (an acid) to whites when beating them in unlined copper; the acid already present in the copper will react to the acidic cream of tartar and turn the whites greenish -- and may make you ill. The author conducted a test to compare egg whites beaten in unlined copper to whites beaten in stainless steel. When two whites beaten in an unlined copper bowl were compared to the two beaten in a stainless steel bowl, the whites in the copper yielded one cup plus two heaping tablespoons. In the stainless bowl, with a pinch of cream of tartar, the egg whites yielded one cup plus one tablespoon. When both bowls were inverted 30 minutes later, no egg whites or liquid seeped out from under the copper bowl and about one tablespoon of liquid leaked from the stainless bowl. After an hour both bowls leaked. This experiment seems to indicate that whites beaten in copper rise at least a little higher and stay firm longer than whites beaten in stainless.

All unlined copper utensils should be used only for the specific purpose intended in order to avoid production of possibly toxic copper oxides which can produces unpleasant gastrointestinal symptoms. It won't kill you, as the old wives tales insist, but it will make you ill.

"Yes, people can get gastrointestinal upsets. But contrary to popular belief it's not fatal," says Dr. Scheinberg, one of the nation's few experts on copper toxicity. He recalls an instance where some nurses mixed whiskey sours in an unlined copper shaker and within 90 minutes, all felt quite queasy. The lemon juice was the villain which produced intestinal discomfort
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The Linings 

Lining copper cookware solves this vexing problem by placing an inert substance between the copper and the food. The metal used for lining is important -- some conduct heat better than others.

The traditional and time-honored lining is tin, mainly because it is almost as good a conductor of heat as copper. Unfortunately the thin coating of tin will melt if subjected to high temperatures (425oF) and will scratch and eventually ware away with use. When this happens, the pans must be retinned in order to avoid the development of toxic substances. Small scratches will not allow significant amounts of copper to leach into foods. If acid foods and metal whisks and spoons, which can damage linings, are avoided, tin linings will last for years -- the copper for generations.

Silver is occasionally (but extravagantly) used as a lining, too. Its heat conduction is equal to tin's but, of course, the cost is high and likely to get worse.

Nickel lining copper is a recent development which is receiving favorable reviews from many sources. It is, experts say, nearly as good as tin in its heat distribution and does not have to be relined as frequently. But when it does need relining, it is difficult to find local craftsmen who can do the job right and the pans usually must be returned to the manufacturer for repairs.

Stainless steel is becoming an increasingly popular lining for copper because it neither melts nor scratches like tin. But some cooks claim that buying stainless lined copper is a waste of money since the poor heat conduction of stainless counteracts the copper's capabilities.