How to boil milk. To prevent milk from running away

Boiling milk is not an easy procedure. How to boil milk without burning it and how to get rid of an unpleasant aftertaste if it is still burnt?

Choice of dishes

It is advisable to use for boiling milk, which is not used for cooking other dishes. The reason for this is simple - when boiled, milk absorbs odors very intensively and hardly anyone will enjoy drinking milk with an extraneous aroma.

If possible, use a saucepan with a thick bottom, such dishes will warm up evenly, preventing the milk from burning.

How to avoid burning

Another way to avoid burning milk when boiling is to rinse the pan with ice water, pour milk into it, and only then put it on fire.

Since water is heavier than milk, a small amount of it will remain at the bottom of the dish, forming a thin film of water that prevents the milk from coming into direct contact with the walls and bottom of the pan.

You can avoid curdling and burning milk if you add a little to it (1 teaspoon per 1 liter of milk).

Boiling milk

Bring milk to a boil over low heat, stirring occasionally. Do not cover the pot with a lid!

Watch your milk closely. The fact that the milk is about to boil is unmistakably indicated by the process of abundant foaming on its surface.

Place a long wooden spoon or spatula on top of the saucepan to prevent milk from escaping as it boils.

At this point, remove the pan from the heat, and cool the milk quickly. How to do it? Pour the milk from the saucepan into a glass jar, and then place the jar in a large pot of cold water. Such milk will be stored much better than cooled gradually.

If, despite all efforts, the milk is burnt, you can get rid of the unpleasant bitter aftertaste if you add a small amount of kitchen salt to it during the process of rapid cooling.

Store boiled milk in a cool and dark place.

Boiling milk always starts suddenly. A cap of milk foam is formed in a fraction of a second. How to deal with escaping milk? And why is it running away?

As the pan heats up, its bottom and walls are covered with small gas bubbles. They most often form at the bottom of the pan - especially where there are traces of fat, grains of sand, small scratches or microcracks invisible to the eye. These bubbles are formed due to the release of gases dissolved in water. The temperature of the water at the bottom is slightly higher than at the surface, so the water near the bottom should evaporate more intensively. But where does she evaporate in the depths?

Here the water finds a way out - it evaporates into the gas bubbles. With an increase in temperature, the amount of vapor in the bubble increases, the bubble increases in volume, and finally, the buoyant force of Archimedes tears it off the bottom, and it floats. When approaching the boiling point, the number of vapor bubbles increases rapidly, and ... the boiling process begins.

On the surface of milk, when heated, a sufficiently strong film is formed - a foam of polymerized milk molecules, which does not allow steam bubbles to come to the surface. At some point, a sufficiently large number of bubbles accumulate under the film that can break through the milk film. And at this moment, the milk “runs away”, although in fact the milk foam that has broken through the film to the surface of the milk “runs away”.

How to learn to control the formation of foam? Where do bubbles mainly rise from?

If there are scratches on the bottom, then centers of local boiling are formed near them, and in the rest of the volume there is an overheated, but practically not yet boiling liquid. Then large bubbles rising from the bottom really bubble up and do not allow a milk film to form on the surface. It is necessary to create pockets of local boiling - and the probability of rapid boiling of milk will decrease sharply. You can put on the bottom, for example, a wire with a rough surface or a plate.

This method is actively used by chemists. By heating various mixtures, they put glass beads or scraps of stainless wire on the bottom. Once upon a time, you could buy a special "milk guard" in stores, made in the form of a stainless steel disc with concentric grooves. The disk is placed on the bottom of the pan, quite a lot of air remains in the grooves - the vapors of boiling milk rush here. As a result, rather large bubbles form at the bottom, which float to the surface through a special neck in the disk. Foam in this case is not formed, and the milk does not run away.

As soon as large bubbles begin to form, the disk will begin to bounce, ringing slightly. Instead, you can also adapt a canning lid - glass or steel. It must be put on the bottom with the sides down - in this case, there will be residual air under it, which, when heated, will expand and rush up with a stream of bubbles, destroying the foam.

For microwave ovens, another method can be used. Pour milk into a bowl, and grease the remaining free inner edges of the walls with butter. In this case, the milk foam reaches the lubrication limit and stops. Physics is physics, but if, when boiling milk, you bring a very powerful heat flux to it, i.e. turn on the fire to the maximum, no tricks will save you - the milk will run away anyway. Therefore, be vigilant!

Source: according to the materials of Zh. "Quantum"

Did you know?

The Volga flows into the Caspian Sea

And where does it start? On the Valdai Hills. This statement seems to be as indisputable as the one in the title. But hydrologists think otherwise.

Studies have shown that millions of years ago, the Volga flowed along the channel of the modern Kama, and its sources were in the Urals. However, even today there is an extensive system of underground rivers, rivers and rivulets that originate in the Ural Range and continue to feed the great river

Where does the sea come from in the shell?

Everyone who tried to bring a sea shell to their ear heard a noise reminiscent of the surf.

What is this noise? Where?

Maybe the shell remembers how noisy her native sea was?

"And your milk ran away ..." (remember where the phrase comes from?) - confusion, annoyance in the eyes of the hostess. Escaped milk turns into a tedious process of rubbing the burnt foam from the stove. And, nevertheless, no matter how hard you try to closely monitor the boiling milk, his escape happens sooner or later. It seems that just a moment ago it didn’t boil, and then once and in a fraction of a second a cap of milk foam forms, which flies up to the sides of the pan and falls out over its edge.

and your milk ran out!

Why does milk run away, and how to avoid it? Have you observed how the boiling process goes in general? In milk, this is not visible, since the medium is opaque, and in water one can clearly observe how, as the metal walls and bottom of the pan are heated, small gas bubbles form on them. These are gases dissolved in water. Bubbles most often form where there are traces of fat, scratches, microcracks. Since the water temperature is slightly higher near the bottom and walls, the evaporation of water begins there. Where does the water evaporate? Inside those bubbles! The bubbles grow, becoming bubbles, and at some point in time, the force of buoyancy exceeds the force of adhesion to the surface of the pan and the bubble floats to the surface. The boiling process, as we imagine it in the form of boiling water, begins when a large number of such bubbles form at once.

What happens to milk? When milk is heated, a polymer film is formed at its border with air - the same milk foam that some of the children love, and some cannot stand. The higher the surface temperature of the milk without intense boiling, the thicker the film layer. The thicker the film layer, the more the surface layer of milk overheats, because the liquid does not evaporate, thereby cooling the surface. In many steam bubbles, such a film also has time to form, resulting in the formation of milk foam. Pop-up bubbles, instead of bursting on the surface, accumulate under the surface of the foam, starting to stretch it and at a certain moment it bursts. It is then that the compressed bubbles of milk foam straighten out in freedom and the hat rapidly flies up the pan.

How to prevent milk from running away. There are several ways. Firstly, the classic one is to continuously stir the milk, preventing the formation of a thick film on the surface. Secondly, local boiling zones can be created. For example, by placing stainless wire trimmings or glass balls on the bottom of the pan. They will become centers for the formation of bubbles, which will rush upwards in a cheerful stream, breaking through the film formed on the surface. Once in stores you could buy a "milk watchman" in the form of a metal disk with concentric circles. It could be put on the bottom of the pot. Shortly before it began to boil, bubbles formed under the disk causing it to bounce, rattling at the bottom of the pot. For this purpose, you can use a saucer, putting it upside down. Evaporation will go under the saucer, from where large bubbles will come out, breaking through the milk foam.

There is also a method that is suitable for microwave ovens. The walls of the dishes, above the level of milk, are smeared with butter. Then the milk foam, having risen to the border of the lubricant, will release bubbles of foam along the edges of the pan, where they will have time to burst safely.

Tricks - tricks, but no one cancels the basic rule: you need to watch the boiling milk carefully!

Milk during cooking often runs away so fast that we do not have time to catch it. Why does this happen and what physical processes are responsible for it? The Village understands kitchen physics.

Andrey Sanin

Professor, Doctor of Physical and Mathematical Sciences, Researcher at the Institute of Physics, Peter the Great St. Petersburg Polytechnic University

The issue of escaping milk cannot be called acute for modern physics. But in general, this is a demonstration process - a good test for assessing understanding of physical processes. A simple answer in one sentence: A pot of milk is filled with gas bubbles that don't burst.

To begin with, it is worth understanding how many small air bubbles generally appear during boiling. It is impossible to notice the approach of this phase in opaque milk. And in the case of water, the process is visual, especially if you watch it through a transparent vessel. As it heats up, that is, with an increase in temperature, you will see that the bottom and walls of the vessel are covered with small gas bubbles. They are formed due to the release of gases dissolved in water. In a thin bottom layer, the temperature is somewhat higher, and water, in theory, should evaporate more intensively. But where does she evaporate in the depths? She finds a way out - evaporates into tiny bubbles. They always form between the vessel wall and the liquid, especially where there are traces of fat or small scratches, microcracks invisible to the eye.

As the temperature rises, the bubble gradually expands until the pressure of the air and vapor inside it is balanced by the external pressure. Finally, the buoyant force pulls it off and it floats up. And a new one is already ripening on the wall.

Milk, in addition to water, contains long polymer molecules. When water evaporates from the surface layers when milk is heated, these molecules adhere and form a strong film. Meanwhile, tiny bubbles appear at the bottom - this is the gas dissolved in the liquid. Water also begins to evaporate inside the bubbles, they grow, and their walls are reinforced with a polymer film. When the bubbles float, they rest against the film on the surface and cannot, as in water, burst and release steam. As the milk approaches the boiling point, the number of bubbles increases, they form foam, which lifts the polymer film. At the same time, the bubbles themselves are strong enough and do not burst. Propped from below with new ones, they quickly overflow the pan.

Understanding the nature of this phenomenon allows you to successfully deal with it. So that the milk does not run away, it is stirred, not allowing the film to appear. The easiest way is if the bubbles themselves rise from the bottom. It is only necessary that they float to the surface already enlarged, then any film will be nothing to them.

The Soviet industry even produced "milk guards" in the form of a stainless steel disc with concentric grooves. Its surface is smooth and easy to clean. The disk is placed on the bottom of the pan, while quite a lot of air remains in the grooves, and vapors of boiling milk tend to come here. As a result, rather large bubbles form at the bottom, which float to the surface through a special neck in the disk. Foam in this case is not formed, and the milk does not run away. You could not even look after him - this is such a physical prototype of today's smart things: as soon as large bubbles formed, the disk began to rumble slightly.

Well, under normal conditions, it is enough to put an inverted saucer on the bottom of the pan, from under which larger bubbles will emerge, and the milk will begin to boil just like water.

Anton Abrezov

head chef of Dreamers cafe

The answer to this question is quite simple. It's all about the density of the milk. Boiling water, for example, never starts unexpectedly - you always notice the little bubbles at the bottom first. They gradually increase in size, the gas inside begins to evaporate and pushes them to the surface. The higher the temperature, the faster this process occurs. So, on the one hand, due to the density of milk, the film around these bubbles is somewhat denser, and on the other hand, when it is heated, water evaporates from the surface layers and a thin film is formed, which does not allow gas bubbles to evaporate. So they pile up and run away. Like people at the subway exit.

The process of "running away" does not depend on the dishes or stove used - the milk will still run away. You can put a saucer on the bottom of the pan so that the bubbles are concentrated at the bottom and the milk above the saucer is evenly heated. In this case, only large bubbles rise to the surface. But then there is a very high risk that the milk will burn. I prefer to just not put a strong fire and stir until boiling.

illustration: Nastya Grigorieva

Conducted by Nastya Sergeeva, 8 years old, and her mother Elena Vasilievna.

Morning!!! The sun is peeking through the window! Summer! Great! Grandmother's voice: "Nastya, it's time to get up, soon the porridge will be ready!" But I don’t want to get up, I’ll lie down a little more .... Suddenly I hear: “Ay, ah-ah, the milk has run away!” How did you run away, where did you run away, why did you run away?????

The milk has run out. Run away!

Rolled down the stairs,

Along the street started,

Flowed across the square

Bypassed the guard

slipped under the bench,

Three old women got wet

Treated two kittens

Warmed up and back:

Flying down the street

Up the stairs puffed,

And crawled into the pan,

Breathing heavily.

Here the hostess arrived in time:

- Boiled?

- Boiled!

Boroditskaya Marina

What happens to milk when we heat it, why does it run away and how to stop it?! What needs to be done so that the milk does not run away?

1. Nastya thinks that you need to take a wide pan, not a narrow one, then the milk will not run away.

2. Mom Nastya says that you need to make the gas quieter.

3. Grandmother says that you need to take a special pan from which milk does not escape.

In the encyclopedia, Nastya read why milk runs away. It turns out that's why:

We know that water exists in three states: vapor, liquid and ice. Milk is a liquid, and if it is heated, the liquid will begin to evaporate, and steam bubbles will form at the bottom. The higher the temperature, the larger the bubbles and they tend upward to the surface. Steam bubbles rise. And a film has already formed on the surface, i.e. foam, so nasty, which children always make their mother clean up! And she doesn't release bubbles one at a time. They are accumulating there, gathering strength! As soon as a lot of them are recruited, the milk wants to escape. And now the milk has already run away!

What to do so that milk does not run away?

Hypothesis #1

If you take two different pots: one small and the other wider and compare how milk boils in them?

Does the escape of milk depend on how wide the pan is?

Let's conduct an experiment: We heat milk in a glass test tube, it quickly ran up! Let's heat the milk in an inclined test tube. Why inclined? Because the inclined test tube is heated more by fire, as if it were a wide saucepan with milk. Milk also quickly ran up! Even faster.

Conclusion: So, it does not depend on the size of the pan whether the milk will run away or not! The speed at which the milk escapes depends on the size of the pan. The larger the contact surface of the pot with the fire, the faster the milk will boil and run away.

Hypothesis #2

Does the escape of milk depend on the strength of the fire?

The stronger the fire, the faster the milk will boil and run away accordingly. On low heat, the milk does not escape as quickly, but it still escapes!

Conclusion: This means that the speed of escape also depends on the strength of the fire. The stronger the fire, the faster it will run away.

Hypothesis #3

Grandmother has a special pan from which milk does not escape.

Why is this happening? This device consists of two vessels, one larger, the other smaller, and they are inserted into each other. IN

water is poured into a large circuit, and milk is poured into the container itself, and a whistle is put on the hole where water is poured. When heated, it starts

boil the water and it evenly heats the milk. When the water boils, the whistle starts to whistle, warning us that the milk will be ready soon.

Since the milk is heated evenly and bubbles do not form, the milk does not run away.

Conclusion: So, the pan helps to make sure that the milk does not run away.

Are there any other adaptations or ways to "pacify" the milk?

To prevent milk from running away you need:

And now Nastya can draw a general CONCLUSION:

After conducting all the experiments, she saw that in order not to run away milk, you need to use devices: special pans for milk, a “milk watchman” or if there is no “watchman” - a simple glass or iron lid to the bottom, and also do not forget about the heating force (weak fire).

Well, young scientists. Now you know the answer to one interesting question that you may have asked your parents after seeing milk run away in the home kitchen. Did you enjoy the experiment? We hope that while visiting your grandmother you will look for a special pan and repeat the experiment. Let's continue learning fun science together. I invite you to explore otherssections of the site. And if you have any questions - ask them to us and we will answer them in the next issue of "WhyMuk".

Bibliography:

2. The poem “Milk ran away” Boroditskaya Marina

3. “First questions and answers about water”, Tatyana Bukhova (translated from English).