Another biggest disadvantage is that it is easy to produce toxic rust, which is what people call copper rust (hehe, like malachite).
However, it is rumored that frying some medicine in a copper pot is very valuable.
There are all kinds of pots in the kitchen: boiling pot, wok, steamer, pressure cooker, milk pot, flat pot ... But judging from the raw materials, there are generally only two kinds: iron pot and aluminum pot.
In the past, people also used copper pots. Humans discovered and used copper much earlier than iron, so it is natural to use copper to make pots first. After the appearance of iron pots, some people still like to use copper pots. Copper is shiny and looks beautiful. Among metals, copper's heat transfer ability is second only to silver and better than iron. The biggest disadvantage of using copper as a cooker is that it is easy to produce toxic rust, which is what people call copper rust (like malachite). In addition, the use of copper pots will destroy vitamin C in food.
With the development of industry, people find it really unfair to use copper as a pot. Copper is small in output and expensive, and can be used to make wires, motors (including chips in computers) and even guns and bullets, which can give full play to its characteristics (bombing the White House). So, the iron pot replaced the copper pot.
In the countryside, the cauldron on the stove is made of pig iron. Pig iron is hard and brittle, so it won't collapse when tapped, but it will break when tapped again. Wrought iron can be used as a wok and an iron spoon. Wrought iron is soft and tough and will not break when it collides. The difference between pig iron and wrought iron is mainly the difference in carbon content. The carbon content of pig iron exceeds 1.7%, and that of wrought iron is below 0.2%. Iron pots are cheap. More than 30 years ago, almost all the pots in the kitchen were iron pots. Iron pots also have shortcomings. They are heavy and easy to rust. Iron rusted, like a scar, and fell off one by one. The heat transfer ability of iron is not too strong, not only inferior to copper, but also inferior to aluminum.
Nowadays, many appliances in the kitchen are made of aluminum or aluminum alloy. Pots, pots, shovels and spoons are almost all made of aluminum. However, a century ago, the price of aluminum was higher than that of gold, and it was called "silvery white gold".
The French emperor Charles Louis Napolé on Bonaparte treasured a set of aluminum tableware, which was only displayed at a grand state banquet. Russian chemist Mendeleev, who discovered the periodic law of elements, once won a lofty award from the Royal Society of England-only an aluminum cup. These stories sound interesting now. Today, aluminum is a very cheap metal. Compared with iron, aluminum has strong heat transfer ability and is light and beautiful. Therefore, aluminum is an ideal material for cookware.
Some people think that aluminum will not rust. In fact, aluminum is a kind of active metal, which can easily combine with oxidation in the air to form a transparent and thin layer of aluminum rust-aluminum trioxide. However, unlike loose rust, this layer of aluminum rust is very dense, which can prevent the inside from rusting like skin. However, this aluminum rust film is afraid of both acid and alkali. Therefore, aluminum pot can't store dishes for too long, nor can it be used to hold vinegar, sour plum soup, alkaline water and salt water. Most aluminum products with rough surface are primary aluminum. Raw aluminum is impure aluminum. Like pig iron, it will break when you hit it hard. Common aluminum products are light and thin. This is cooked aluminum. Aluminum alloy is smelted by adding a small amount of metals such as magnesium, manganese and copper to pure aluminum, and its corrosion resistance and hardness have been greatly improved. Pressure cookers and kettles made of aluminum alloy have been widely sold in the market. In recent years, anodic oxidation products have appeared in shops. This is because aluminum is oxidized by the electrode, which makes the aluminum rust layer on the surface thicker and forms a loose and porous adhesive layer, which can firmly absorb dyes. Therefore, the surface of this aluminum lunch box, rice cooker, kettle, etc. Can be dyed into bright colors, making aluminum products more beautiful and attractive.
Aluminum pot also has its shortcomings. Excessive intake of aluminum can easily lead to Alzheimer's disease. So you'd better use stainless steel pot.
There is an old saying that people will die overnight. It is also very popular to pack wine in tin pots in rural areas. Everyone must pay attention. If you have a stomachache after eating, the doctor may not see your cause when you go to the hospital. In fact, this is called "lead poisoning".