The principle of milk foaming latte coffee flower drawing tutorial to make a smooth milk foam tutorial

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A good latte, in addition to espresso, milk also plays an important role. I believe you will find that the milk used in most cafes to make milk coffee is fresh milk that needs to be refrigerated, and it is rare to see milk that can be preserved at room temperature. why? Do you have to refrigerate fresh milk to make latte? How to choose the milk suitable for coffee flower?

How do the main ingredients in milk affect a cup of coffee?

Milk is mainly composed of protein, fat, carbohydrates and gray matter, in which protein plays a role in forming and stabilizing milk bubbles, fat increases the mellowness of coffee and further stabilizes milk bubbles, and carbohydrates increase the sweetness of coffee.

| | protein |

Milk is mainly composed of casein and whey protein.

When we use a steam stick to heat and stir the milk, whey protein slowly "unfolds" to form a film to wrap around the gas, creating many bubbles of different sizes. The surface of the bubble will be covered with casein particles containing surfactant, so that the interface between the bubble and the liquid produces a certain degree of surface tension, so that the bubble is not easy to burst.

| | Fat |

The content of milk fat determines the mellow feeling of milk and the role of stabilizing milk bubbles.

Compared with skim milk, whole milk and cream, it is not difficult to find that skim milk brings a thin, light feeling to the mouth; whole milk brings a mellow, smooth feeling to the mouth; cream brings a thick, sticky feeling to the mouth.

When the milk is heated for more than 40 ℃, the lipids in the milk will melt. The density of melted lipids is lighter. Can attach to the surface of the bubble to form a film, once again "strengthen" the surface of the bubble, so that the integration of milk foam and coffee can be more stable. This also explains why skim milk foams dissipate faster when blended with coffee than whole milk.

| | carbohydrate |

The carbohydrates in milk are mainly lactose.

Lactose is not as sweet as fructose. If the sweetness of sucrose is 1.0, lactose is only 0.16. Interestingly, although the sweetness of lactose is not obvious, the sweetness of the taste increases or decreases with the change of milk temperature.

Between 60 ℃ and 70 ℃ is when lactose and other sugars are the most "active". When milk is mixed with coffee when it reaches this temperature range, you can feel the sweetness of both smell and taste in this cup of milk coffee without sugar. (of course, if espresso is not extracted properly, no matter how sweet milk can save bitter coffee.)

What are the requirements for milk for coffee flowers?

As mentioned above, protein and fat are the most important factors affecting milk foaming and foam stability. Is it true that the higher the protein and fat content of milk, the more suitable it is to make milk foam for coffee flowers?

It is not that higher protein content can really improve the foaming property of milk. But if the fat content is too high and the weight of the dissolved foam is beyond the capacity of the bubble, the foam will collapse. Studies have shown that milk with protein content of about 3.2% and fat content of about 3.7% will achieve a better balance between foaming and foam stability. The second is that the high fat content of milk will mask the taste of coffee.

Do you have to refrigerate fresh milk to make lattes?

In fact, as long as the protein content and fat content are enough, there is no requirement to use frozen milk to make lattes. UHT normal temperature milk can also make lattes. Then why do cafes like to make lattes from frozen milk? Qianjie has talked to many people in the coffee industry and synthesized the views of all sides.

The main reason for choosing fresh milk is freshness. The shelf life of refrigerated fresh milk is generally within 7-15 days, while the shelf life of ultra-high temperature sterilized (UHT) milk can be more than one month, and does not need cold storage. This will give consumers the most direct impression that UHT room temperature milk is too low-end and should not appear in cafes.

Secondly, when drinking normal temperature milk and fresh milk, most people will feel that the whole of refrigerated fresh milk is stronger than UHT normal temperature milk. Even if the protein and fat contents of the two are similar, there will be a gap.

Then there is the stability of the foam. Although UHT normal temperature milk can also produce dense and delicate milk bubbles, the foam dissipates faster when mixed with coffee than fresh milk. Many people find that the stability of UHT milk at room temperature is very dangerous. the foam of the last batch of milk is good, but the foam of the next batch of milk is suddenly unstable.

To sum up the above point of view, Qianjie believes that both fresh milk and UHT room temperature milk can make lattes. However, compared with the quality of milk, fresh milk has a stable supply chain, the quality will be more stable than UHT normal temperature milk, and can be better guaranteed in daily production.

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