Cook the meat's foam in the pot.
Why is there foam in the pot in cook the meat?
Most of this floating foam is the blood of animal raw materials, containing protein, etc. When protein is heated to 70 degrees, it will undergo thermal denaturation and solidify into a block. Pig blood and sheep blood, which are often eaten, are made according to this principle, but the production methods are different. These collagen proteins, after high temperature, are destroyed to form colloid, which will bubble on the surface area, and there are suspended solids in blood, so we see gray foam! Without nutrition, it also affects beauty and taste!
Careful friends will find that the number of floating foam produced by cook the meat in different parts is different, precisely because the number of capillaries in different parts is different. Meat with clear lines, such as pig's back, has clear lines and few capillaries, so it is easy to wash away the residual blood, so there is less foam when cooking soup. However, for meat with complex lines and rich capillaries, such as leg meat and shoulder meat, it is difficult to clean the residual blood in the meat, so there are more bubbles when cooking soup.
Why does blood become foam when heated? This has to be analyzed from the composition of blood. Let me take pig blood as an example to explain why pig blood forms foam when heated. At this time, we need to understand the principle of foam formation: food foam is usually a dispersion system formed by bubbles in a continuous liquid phase or a semi-solid phase containing soluble surfactants, as shown in the following figure.
Floating-point generation principle
Simply put, it is the same as the principle of children blowing soap bubbles, and it is also the same as the foam produced when egg whites are whipped. We all know that pig blood is rich in hemoglobin, accounting for 18.9% of blood. Hemoglobin is a kind of protein with excellent solubility, which can form a stable foam. In pork soup, the gas is air or CO2, and the continuous phase is pork soup. When water boils, the air dissolved in the water will be separated. When the temperature rises to 100℃, hemoglobin denatures, destroying the second, third and fourth structures of hemoglobin, and then hydrogen bonds and disulfide bonds open, thus exposing polypeptide chains. Polypeptide chain can combine with bubbles in soup, which makes protein expand in volume and form foam. Having said so many technical terms, in fact, this layer of foam is the combination of hemoglobin and gas, which increases the volume of hemoglobin, so the foam is formed.
You got it? So this kind of floating foam is harmless. No matter what form hemoglobin becomes, it is still protein. Don't be deceived by its appearance.
Skim off floating foam
How to remove floating foam in meat cooking
1, soak the ingredients in clean water for a long time and change the water for many times. For example, the meat and beef bones in mutton soup should be soaked for one day, and it is best to use running water;
2. Some ingredients are scalded with boiling water before stewing the soup, and then cooled before making soup;
3. After the above treatment, some ingredients will appear some foam when stewing soup. At this time, use a colander (there is also a special net spoon for skimming floating foam) and other tools to skim the upper floating foam in time!
Seeing this, are you not so afraid of the soup foam? ! !
From the perspective of senior foodies: this layer of floating foam has a fishy smell and a bad taste. It is recommended to remove it.
Braised pork
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