Measure powder, cloth powder, slightly pressed, align with the card slot, and clamp the handle. Wait quietly, extract the coffee liquid, and slowly complete the gathering in the small glass.
What exactly are we drinking when we drink Espresso? It is certain that before tasting it, the eyes and nose will feel another concentrated flavor before the lips and tongue – when the aroma is overflowing, the dark brown coffee liquid sinks to the bottom, and the surface is suspended with a layer of caramel-colored foam, which is rich and seductive. This layer of foam is the scenery that the eyes see before the mouth – commonly known as “coffee fat”. Many coffee lovers use it as one of the indicators when evaluating whether the concentration is good or bad.
An ideal glass of Espresso should be a balance of elements, with a distinct taste and a sweet feeling in the throat after drinking. © Pinterest
“Seeing how thick and dense the grease is, the quality of this Espresso is really good.”
“There are tabby stripes, hurry up and take pictures!”
Backed by this view, under the slogan of the espresso machine business, whether a cup of Espresso is finished with rich grease or not, whether tabby lines form on the surface of the foam, and taste it with the eyes rather than the tongue, coffee lovers first secretly score a score in their hearts.
But is there a direct and definite relationship between fat and the quality of an espresso? Or is the coffee grease that many people are pursuing actually a meaningless niche carnival?
Coffee beans themselves contain certain fatty compounds, and the commonly known coffee fat, Italian called “Crema” – in fact, after caffeine, its own water-soluble fatty compounds and carbon dioxide briefly combined products.
The carbon dioxide here does not come from the air, but from the wonderful internal transformation of the coffee beans after heating. From coffee beans to a cup of coffee, it is necessary to go through the steps of picking, roasting, milling, extraction, etc., in the roasting process, coffee beans under the action of heat, the internal substances carry out chemical reactions, releasing a large amount of carbon dioxide.
When making Espresso, hot water is washed over the coffee powder under the high pressure of the coffee machine, and the coffee liquid and water-soluble fatty compounds are fully extracted. At the same time, the carbon dioxide brought by roasting in the coffee powder is also dissolved in the coffee liquid in large quantities under the catalysis of high pressure.
Espresso means “particularly fast” in Italian and is characterized by the use of steam pressure to instantly pump out the coffee liquid. © imgur.com
Although the high pressure allows carbon dioxide to dissolve in the coffee well, the pressure decreases sharply after leaving the coffee machine and entering the glass, and the carbon dioxide takes advantage of this opportunity to prepare to escape the coffee liquid and return to more stable air.
This is the same as before drinking carbonated drinks, in order to avoid carbon dioxide spraying out, we will gently unscrew a little cap to fully release the carbonic acid in the bottle before drinking, as the pressure changes, dissolved carbon dioxide will precipitate from the water.
But in general carbonated drinks, carbon dioxide “run” is just running, at most rushing out of the bottle, will not bring out other substances. Espresso is different, the fat compound is lighter than carbon dioxide, and it is successfully wrapped in small bubbles before the carbon dioxide precipitates, rampage, and finally condenses into a beautiful foam on the surface of the coffee liquid.
This is the whole process of the birth of coffee fat.
Due to the need for high-pressure assistance, only an espresso machine can generally produce an espresso with a layer of foam
(Only a few mocha pots can force grease)
It is difficult to make this “highly respected” layer of coffee fat by hand extraction.
But the factors that affect the “oil yield” are not only pressure. The freshness of the beans, the oil content of the beans themselves, the degree of roasting, the thickness of the coffee powder, and the proportion of gouache are all intertwined to determine whether a cup of Espresso is as rich and cute as expected.
As with the flavor, the amount of coffee bean fat is also different depending on the origin, for example, the lipid content of Robusta seed beans is about 10%, and the aracabi beans are about 15%.
The freshness of the beans refers to the time the beans are stored after roasting and before milling, and the beans will exchange gas with the air for too long, and the more carbon dioxide is lost, the less coffee fat will be presented.
The degree of roasting is one of the important factors that affect the flavor of a cup of coffee. © Pinterest
Roasting is the most powerful catalyst for coffee flavor, after fermentation and drying treatment of coffee beans after heat action, the skin turns black, loses moisture, and the compounds inside change rapidly, transforming into an intriguing aroma. The deeper the roasting, the more carbon dioxide is released inside the beans, and after milling extraction, it can naturally work with more fatty compounds to present a rich posture on the coffee surface.
The thickness of the coffee powder and the proportion of water powder are also the key to whether the “beautiful” oil can be produced during the extraction stage. If the grinding is insufficient, the extraction rate will decrease, and the fat compound will naturally become smaller; Similarly, if the same amount of powder, if the proportion of water powder is higher, the amount of coffee fat produced will be reduced accordingly.
Ultimately, the factors that affect the carbon dioxide content and fatty compound content of the coffee beans themselves are the decisive conditions that define whether a cup of Espresso has oil.
Back to the original question: if you extract dense and delicate coffee fat, must it be a good cup of coffee?
On the Zhihu platform, a netizen asked: “Is it cheaper coffee beans.”
(Freshly baked)
The richer the oil? I also know this is probably a false proposition. But in a certain treasure, different sellers have bought more than a dozen kinds of coffee beans, and the cheapest one turned out to be the thickest, which is really tempting. This makes me very uneasy, could it be that the seller added some special ingredients when baking?”
His question is intuitive – cheap beans produce more oil and are more abundant. This may be because the flavor of this bean is not very good, in order to enhance the overall taste of coffee, the degree of roasting will be increased to balance the innate deficiency and increase the mellow aroma of the beans.
The yield of coffee fat is affected by a variety of factors, some of which can even affect the flavor of coffee. For example, the result of deep baking just mentioned is to increase the amount of fat and cover up some imperfections. However, the amount of fat in result 1 and the flavor of result two are not directly related and positively affected, and not all deep-roasted beans are inferior beans. In the process, the amount of fat in the coffee is increased, but it does not prove that the beans in this Espresso cup are better than the high-priced coffee beans.
In Italy, the price of a glass of espresso is controlled by the government. © diaryofdays
In fact, the real role of coffee fat in concentration is: to increase the taste and make the mouth dense; Acting as a bodyguard to protect the flavor of coffee; Convenient to pull flowers, support pattern.
The coffee is rich in fat, so Espresso adds a little delicate taste when you eat it. However, coffee fat is not the richer the taste, if there is too much coffee fat, too many fatty compounds accumulate on the surface of the coffee, and it may be astringent when drinking, but affect the flavor of the coffee itself.
That layer of oil is attached to the surface of coffee, like a protective film, which can effectively prevent the loss of aromatic substances in coffee. But this “protection” time is short, Espresso is ready to enjoy as soon as possible, leave it for too long and the foam disappears and the flavor is gone.
In addition, when making latte with Espresso, the thick and rich coffee fat can better support the milk pull-out pattern, allowing beautiful ideas to last longer.
As for the “tabby pattern”, some of the fine powder is filtered into the cup during extraction, causing some dots on the foam surface of the grease and the color to look a little dark. If I have to find a little meaning, it is that the pictures are really beautiful. But for coffee flavor, whether it is that layer of foam or a small amount of falling coffee powder, the impact is not very large.
The color of Espresso foam varies from dark brown to light brown under the influence of different factors; The grease in the lower left cup shows tabby marks. © sohu.. .com
To judge the quality of a cup of coffee, you should rely on the tongue to taste. Food has no fixed taste, palatable is cherished, coffee is the same, for individuals, coffee flavor, aroma, body, acidity, can be used as a reference factor for judging and scoring.
These factors are closely related to the origin of coffee, roasting degree, and production method, and compared to these determining conditions, coffee fat is more like an accident in the production process, a beloved by-product, and the water meets.
It can add some fun, the same coffee powder is extracted by hand, you can’t see the thin layer of foam, but the coffee extracted by hand can also have a pure taste.
Simply put, it is understandable to appreciate the rich and delicate gesture of coffee fat, but it is a bit far-fetched to insist on linking “flavor” and “scenery”.
Thanks to Big Cat Teacher for your help with this article.
Resources:
Barista Cultivation | About the Q&A of espresso (a) Is the tabby fat on the surface of espresso normal? 》Front Street Coffee
《What is crema？ 》Clive Coffee