What is milk foam: the principle and way of milk foaming affect the factors of milk foaming

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Guide reading

Many friends in the Italian style have a heart to pull beautiful flowers, and the premise to pull out a beautiful pattern is to make delicate and dense milk bubbles, of course, delicate and dense milk bubbles are not only for looking good, but also add a better taste to a cup of milk coffee. This issue of Qianjie Coffee will teach you how to get rid of milk bubbles!

The way to get rid of the foam.

There are many ways of foaming milk, but it can be roughly divided into two categories: one is the combination of milk and milk foam. The other is to separate the stages of getting rid of and beating off, that is, to send the milk first and then beat the milk foam. This time, in order to better explain, we will share the separate forms of the stages of killing and sleeping together, so that we can better understand.

Get ready to get rid of the foam

First of all, we have a steam bar, the general semi-automatic coffee machine will be equipped with steam bar, followed by the need to hold milk containers, such as milk vat or flower jar (professional equipment will get twice the result with half the effort).

Finally, when it comes to the choice of milk, no matter normal or low temperature milk, whole milk or skim milk can get rid of foam, but if you want the milk to have better texture, taste, stability and durability, Qianjie still recommends using frozen whole milk.

The principle of getting rid of milk foam

Open the steam bar button, you will find that there are 4 air vents (different brand models will be different, there are single hole, 2 hole, 3 hole), if we are half buried in the milk surface, open the steam bar button, at this time to air to blow off the foam; if all buried in the milk, it will not dismiss the foam, but will only heat the milk through hot steam!

Demonstration of passing away milk foam

1. The best capacity of milk: a reasonable capacity is needed to dispense with milk. It is recommended to use 40-60% of the total capacity of the milk tank in front of the street. Too little milk and too much milk test the technology. Of course, in addition to this factor, it also depends on the amount of milk you actually use in a cup of coffee to avoid excessive waste. In the past, the capacity of the milk tank used in the street was 550ML, and the amount of milk injected was 250ML (just at the bottom of the nozzle).

(the solid line is the amount of milk, and the dotted line is the capacity after discarding)

2. Dispatch position: before preparing to dismiss, turn on the steam bar switch and release the condensed water vapor (turn off the switch after release). Then pull out the steam rod at an angle of 45 degrees, using the cylinder nozzle to stabilize the position of the steam rod, the steam vortex is counterclockwise, the position of the steam rod is on the right side of the cross in the center of the liquid level, and the steam rod is semi-buried.

3, the killing stage: turn on the steam switch and you will hear the sound of "squeak-squeak". At this time, the time spent is different according to the thickness of the foam required (the longer the time is spent, the thicker the foam is). Usually beat 50% of the milk to 60% of the amount (latte foam thickness) to pass the time in about 3 seconds. The direction in which the milk turns uniformly forms a whirlpool.

4. Beating stage: at this time, the steam hole needs to be fully buried, only heated and no longer sent. Do not bury the steam hole at the bottom, it is recommended to be in the milk foam layer, which is beneficial to make the rough foam delicate. When will it stop? It depends on your milk temperature, which is generally controlled between 55 and 65 ℃. Too high temperature can denature proteins (generally speaking, thermal denaturation of proteins in food occurs at about 60 ℃).

Delicate and dense milk foam, showing a solidified yoghurt when shaking, the surface is delicate in the shape of a reflective mirror, silky and slippery.

How many degrees is the right temperature for milk?

In order to explore the effect of temperature on coffee, Qianjie Coffee tried to use milk temperature as a variable to taste the taste of milk at different temperatures and the taste and taste of lattes made from milk at different temperatures. to observe the effect of milk at different temperatures on flower drawing.

Milk temperature

Milk taste and sweetness

Milk fluidity

The taste of latte

Group A

4 degrees Celsius (unsent)

Smooth and medium sweetness

Group B

39 degrees Celsius

Smooth and medium sweetness

Higher

The milk foam is slightly thinner, the sweetness of milk is obvious,

Group C

52 degrees Celsius

Slippery, moderately high sweetness

High

The thickness of milk foam is moderate, sweet and comfortable as a whole.

Group D

71 degrees Celsius

Dense, low sweetness

Low

The milk foam is too thick and the overall temperature is too high, hindering the mouth.

It can be seen from the results that the milk temperature in group C is the most suitable, with high sweetness and dense foam, and the temperature is not too high to cause hot mouth obstruction.

But why did it end up like this? We need to start with what milk contains.

Fat

Fat

Fat affects the thickness and quality of milk and the durability of milk bubbles. The more fat the milk is, the more mellow the milk is and the longer the foam is retained. Another effect of fat on milk bubbles is that the less fat, the more protein likes the air filled with milk, resulting in more milk bubbles.

Sugar

Sugar

The sugar in milk is lactose, which is the source of sweetness that we can sense directly, even without adding extra sugar. But as the temperature rises, our perception of sweetness becomes difficult to recognize. As we often say, "you can't eat hot tofu in a hurry", which also reflects the fact that food is in a state of high temperature. our senses are more difficult to taste.

Protein

Protein

When we beat the milk, as the temperature rises, the protein will slowly unravel and become hydrophilic at one end and hydrophobic at the other. When we put in the steam in the process, the hydrophobic end will avoid the water in the milk and fall into the bubble, causing the bubble to form a hydrophilic barrier, also known as "surfactant".

The quality of protein surfactant also determines the quality of milk bubbles. But once the temperature exceeds 70 degrees Celsius, the protein will denature or decompose, which can cause the bubbles held by the protein to burst, causing the foam to deteriorate.

Combined with the above, the recommended temperature of milk is between 50 degrees Celsius and 60 degrees Celsius. Proper heating can help us send out dense milk bubbles and more obvious sweetness. At the same time, we should also pay attention to the fact that the temperature should not be too high. Once the protein is heated above 70 degrees Celsius, it will denature or decompose, causing the foam to burst, and the high temperature will make the coffee difficult to enter.

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