For many years, aluminum cookware has been comfortable with most housewives. It is light (density of only 2.7 g / cm3), durable, and then this ware was very cheap. But the main positive quality is that aluminum is a good conductor of heat. Water boils in such a pan rather quickly.
Aluminum and enameled cookware, advantages and disadvantages, compatibility with products, mechanical and domestic properties, thermal conductivity.
The thermal conductivity of the materials from which cookware is made is a very important indicator. Better than aluminum in thermal conductivity, only copper. In the old days, most cookware was actually made of copper, especially since aluminum was unknown. Due to the fact that aluminum was much cheaper than copper, aluminum cookware has become very common.
Aluminum cookware is usually thin-walled, stamped. This also makes its price very affordable. But besides these advantages, the remaining qualities of aluminum are continuous flaws..
Aluminum cookware too soft.
Pots, pans and lids made of pure aluminum are easily deformed. This you yourself may have seen. Therefore, for the manufacture of glassware, aluminum alloys are used, which make it harder, the thermal conductivity is reduced, but remains quite high. Alloys may include magnesium, manganese, zinc. All these substances are by no means inert, and they are able to react with food..
And chemists say about aluminum itself: a very base metal. Because he is chemically too active. To begin with, it actively reacts with atmospheric oxygen. Its surface is quickly covered with a dense oxide film, which prevents the further access of oxygen to the metal and leads to the termination of the reaction. It would seem good. The oxide film gives the aluminum cookware anti-corrosion properties.
But this film is very thin, and aluminum kitchenware is easily scratched. Previous generations already ate a lot of aluminum shavings. They write that it causes very unpleasant diseases. And if the food burns, laundered this kitchenware with difficulty. You can’t scrape aluminum with a metal washcloth or a brush, and even more so with emery, as some crazy-minded housewives liked to do..
Aluminum cookware reacts actively with alkalis and acids.
In addition, the protective oxide film is easily dissolved by alkali solutions. And many foods just have an alkaline reaction. For example, potatoes, green sorrel soup, many soups. Following this, aluminum exposed from under the oxide film reacts, forming compounds that are not harmless to our health.
Aluminum also reacts actively with acids. Except for concentrated nitric acid, but it’s a little comfort, right? And such dishes as cabbage soup, borscht, meat in sweet and sour sauce, jelly, berry jam, compote – all of them have an acid reaction. As a result, aluminum compounds pass into our dishes from the walls of pots and pans..
Sulfur as a result of interaction with aluminum during heating forms aluminum sulfide, which, according to the references, is decomposed by water into aluminum hydroxide and hydrogen sulfide. The one with the smell of rotten eggs, which in large quantities is poisonous. In addition, products containing sulfur, calcium, leave ugly dark marks on aluminum utensils. These are eggs, dairy products, pickles.
Even if you are ready to come to terms with dark spots on the inside walls of pots, it is not recommended to leave cooked food for storage in aluminum utensils. And when heated, aluminum reacts with halogens. This is, for example, chlorine contained in tap water. Tell me, do we need all this? Therefore, in EU countries, cookware where food comes in contact with aluminum is now completely banned.
Aluminum in the manufacture of modern cookware.
But before all this was forgiven for aluminum for its cheapness. But aluminum did not fit into the new popular glass-ceramic hobs. From aluminum pots on glass ceramics, irreducible pearlescent stains appear. Therefore, today, when there is a much wider choice of materials for kitchen utensils, it would seem that aluminum has passed an irrevocable sentence.
And no! Although aluminum has risen in price, today it is still widely used for the production of quality cookware. The trick is that now it works in combination with stainless steel, non-stick coatings. In modern dishes, food contact with aluminum is not allowed, but its ability to quickly heat up and accumulate heat is successfully used..
Enamel cookware, advantages and disadvantages.
For a long time, an alternative to aluminum was enameled cookware, more expensive. Now it is one of the cheapest types of cookware. This is a massive, rather heavy dish made of cast iron or black steel (density 7.6–7.86 g / cm3), on the surface of which a durable glassy enamel coating is applied in 2-3 layers.
The smooth glassy surface is quite hygienic. It prevents the growth of bacteria; the smell of food does not linger on the walls of dishes. Modern enamel is very durable, resistant to salts, acids and alkalis contained in food, in such dishes you can cook and store any dishes.
The enamel coating is selected so that its coefficient of thermal expansion is the same as that of a steel or cast iron base. Due to this, the enamel does not fly off when heating dishes on the stove or when cooling slowly.
And yet, if you pour boiling water in a cold pot or cold water – in a heated one, the enamel may begin to crack. Water penetrates the metal through the damaged area and corrosion begins. As a result, iron oxides may appear in food..
Mechanical properties and thermal conductivity of enameled cookware.
And the mechanical properties of enamel and metal are all the more different. And when you, having tasted with a spoon what kind of borsch you have, in forgetfulness hit it on the edge of the pan to shake off the leftovers, the enamel will inevitably begin to crack. At first this happens near the handles, where the mechanical stresses are inhomogeneous. Then enamel crumbles at the sides. Black metal is not exposed under the enamel, not intended for contact with food.
It is already impossible to cook food in such dishes, even water should not be boiled. You can be poisoned by metal compounds. It is better to throw out such a crumpled pan with broken enamel. True, the thicker and more massive the kitchenware, the better it resists shock..
The thermal conductivity coefficient of cast iron and steel, which form the basis of enameled cookware, is significantly lower than that of aluminum. The enamel layer has a lower thermal conductivity, approximately the same as that of glass. Therefore, the heat from the burner is not immediately evenly distributed throughout the bottom, foci of overheating are formed, and in enameled dishes the food burns easily.
The reason for this is the high adhesion of enamel. For example, try boiling milk in an enamel pan. If you do not mix it non-stop, it will definitely get a nasty burned aftertaste. It is not worth washing off burnt enameled dishes with abrasive substances and brushes. Microscopic cracks and scratches form on the enamel. They are not visible, but they are, they are clogged with dirt, and you again tear off the dishes, and so on to infinity. It is neither us nor enamel useful..
Enamel Cookware Coatings.
At first, enameled cookware was made only white. Dark enamel is now widespread. And even light enameled pots now make a specially blackened bottom from the outside. Heating such a pan over a fire will go somewhat faster. At the same time, according to the standards, the enameled kitchen utensils can be of any color outside, but only white inside.
If you do not beat enameled dishes, do not drop them, do not knock on the edge of the dishes with a spoon, do not scrub with metal washcloths and do not put them on fire, it can last a long time.