Many friends will ask what are those disgusting bubbles floating on the noodle soup when cooking broth? Many friends will definitely have such questions. The following small series from Xi 'an Weidian Shaanxi Snack Training Center will discuss with you.

Float in cook the meat

Why is there froth in cook the meat

Most of this froth is the blood of animal raw materials, including protein, etc. When protein is heated to 71 degrees, it will undergo thermal denaturation and solidify into blocks. Pig's blood and sheep's 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 foam on the surface area, and the suspended substance dregs in blood water, so we see gray foam! No nutrition, but also affect the beauty and taste!

Careful friends will find that the amount of foam produced by cooking meat in different parts is different, which is precisely because the number of capillaries in different parts is different. Meat with clear lines, such as pork back, has clear lines and fewer capillaries, which makes it easy to wash the residual blood, so there is less foam when cooking soup. However, it is very difficult for meat with complex lines and rich capillaries, such as leg and shoulder meat, to clean the residual blood in the meat, so there are more floating bubbles when cooking soup.

why does blood become foam after heating? 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 after heating. 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.

principle of froth generation

in short, it is the same as the principle of children blowing soap bubbles, and it is also the same as the bubbles generated when egg whites are whipped. We all know that pig blood is rich in hemoglobin, and the hemoglobin in pig blood accounts 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 the water boils, the air dissolved in the water will be separated out. However, when the temperature rises to 111℃, hemoglobin denatures, destroying the second, third and fourth structure of hemoglobin, and then hydrogen bonds and disulfide bonds open, thus exposing the polypeptide chain. The polypeptide chain can combine with bubbles in the soup, so that the protein expands in volume and forms foam. Having said so many technical terms, in fact, this layer of foam is that hemoglobin combines with gas to increase the volume of hemoglobin, so it forms foam.

do you understand? Therefore, 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 the floating foam

How to remove the floating foam when cook the meat

1. Soak the ingredients in clear water for a long time, and change the water several 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 boiled in boiling water before stewing the soup, and then cooled before making the 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 net spoon specially used for skimming floating foam) and other tools to skim the upper floating foam out in time!

seeing this, are you not so afraid of the foam in the soup? ! !

from the perspective of senior foodies, this layer of floating foam smells fishy and unpleasant, so it is recommended to remove it.

Braised pork

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