Remember the film on milk from childhood? Someone liked it, but someone categorically did not want to drink such a drink. Only then we did not know why it is formed. In this article you will find the answer to this question.
Milk properties
A fresh drink, when shaken on the walls of the glass, does not leave any traces, but the sour product, on the contrary, sticks to the surface of the dishes. Particles in milk, stretching in the form of threads, indicates its mucus. It is impossible to eat such a product.
You should also pay attention to the color of milk. It should have a white or bluish tint.
If the milk is blue, then it has bacteria. The reddish drink most likely contains blood or any microorganisms.
When examining milk under a microscope, you can see a fairly large number of fat droplets that are enclosed in a protein shell. When heated, they partially break down. In this case, protein coagulation occurs. You can learn about further action in the next section. It will explain in detail why a film forms on milk.
What does milk foam consist of?
Simply put, this is just fat, but more complex in composition. It consists of minerals, proteins, such as albumin, casein and globulin.
As a rule, mistresses remove foam from it before consuming a drink. So, a dense film on the surface of a cooled milk is difficult to swallow whole. This is explained by the fact that the colder the drink, the thicker the consistency of the foam.
There are also two types of film on the drink.
One of them is formed during the upholding of whole milk. It mainly contains only fats. The second type of film is obtained by boiling milk.
Foam is formed when the temperature of the drink standing on the stove reaches 50 degrees. Due to this effect, milk protein changes its qualities, leading to such results.
As a rule, housewives try to get rid of the film on milk at the time of boiling. It is she who completely covers the surface of the drink and does not let air through. When boiling milk, rising from the bottom of the pan, he does not find a way out. And then the milk "runs away." You will learn about this process, why this is happening and how to prevent this from happening, by reading one of the sections of this article.
How does the foam form?
During boiling milk, proteins (mainly albumin) are curtailed. And calcium and phosphorus, which is also in this drink, are converted into insoluble compounds.
Milk fat absorbs the resulting solids and an entire film forms. It can be removed with a spoon in a single layer.
In cooking, there are recipes that describe how to dry or freeze such a foam. After that, it is cut into small portions and served.
What will be the thickness of the film on milk depends on the fat content. Most of it is with a real whole product. For example, from milk from a grandmother in a village. Here no one handles it like a storefront. But there may not be a film on purchased milk.
Harm from foam
No matter how strange it may sound, but it can be. After using this product, a number of people experience headache and nausea, intestinal upsets, and itchy skin.
The reason is that a person has a lack of lactose. This is an enzyme due to which the breakdown of milk sugar in the body occurs.
Another source of contraindications to the use of the drink is an individual intolerance to the product. In this case, refuse milk. Also, in case the symptoms persist, it is best to consult a specialist.
When your child does not want to drink warm milk because of the film, you should remove it before you put the drink on the table. It is also possible to replace this product with others, such as kefir and yogurt.
What happens when souring milk?
In this case, the action of sour milk bacteria begins. They have an effect on milk sugar, which subsequently turns into lactic acid. The last component causes protein coagulation. As a result, some parts of the fat droplets are destroyed. After that they rise up and unite. Thus, together with protein molecules, sour cream is obtained. If it is well beaten, then the fat droplets will lose the protein shell and stick together. Then oil is formed.
How to wash milk dishes?
In hot water, fat droplets melt and adhere to the glass wall. Then it will be difficult to remove it. And cold water, in turn, can not violate the integrity of fat cells. These residues are easily washed off if the dishes did not stand unwashed for a long time and the milk did not dry on its walls.
An interesting fact is that casein, which is formed as a result of milk coagulation, can be used as glue. It is very difficult to wash.
But there is a way that allows you to enjoy quickly clean dishes. To do this, a glass with the remains of milk is first washed in cold water, and then in hot. Thus, you wash off the fat droplets, and then clean the dishes from other dirt.
Why does milk run away?
Have you observed how this boiling process occurs? Maybe yes. But in milk this is not visible. But in water, you can consider how, due to the heating of the metal bottom and pan walls, small gas bubbles appear on them. They are formed, as a rule, where there are scratches or traces of fat. The water temperature at the bottom and walls is higher, so it is there that it starts to evaporate. Because of this, the bubbles become larger, and at some point float to the surface. The process of boiling water begins when there are more of them.
But when the milk is heated, a polymer film is formed. And the higher the surface temperature of the drink, the thicker the layer of this formation. Pop-up bubbles do not burst, as occurs during boiling water, but accumulate under the foam. They stretch it, as a result of which it bursts. At this point, the compressed bubbles are straightened. Then the film in boiled milk flies up the pots.
How not to let milk run away?
There are several ways to prevent this from happening.
Stir it constantly so that a thick film does not form on the milk.
You can also put glass balls or a piece of stainless wire on the bottom of the pan . They will be local boiling zones. It is there that bubbles will form, which will subsequently head up and break through the resulting film in milk.
In addition, a saucer can be placed at the bottom of the pan. It should be located upside down. Evaporation will occur under this cookware. And air bubbles, as described above, will break through the milk film.
And how to trace the drink, which is usually placed in the microwave? For this, the edges of the dishes in which the milk will be located should be greased with butter. In this case, the foam rises to this very border and releases bubbles at the edges, for example, pots. It is they who burst here.
If you do not apply these intricate tricks, then you need to carefully monitor the milk, otherwise it will “run away”.
After reading this article, you can answer the questions of your children about the appearance of a film on milk. Due to the content of useful microelements in this product, this product is very useful for both adults and children.