What is espresso? Espresso is a very small cup of coffee that can be finished in about two or three sips. Its taste is very strong, which is difficult for many people to accept. The small cup size and strong taste are the reasons why espresso has a small audience in China, but latte coffee mixed with milk and Americano coffee mixed with water are very popular.
The appearance of espresso in the cup is black espresso liquid underneath with a layer of golden coffee crema floating on top. Is coffee creme an oil?
We all know that peanut oil is squeezed from peanuts, and oil will ooze from the surface of dark roasted coffee beans. So what is the layer of fat in the espresso pressed out of the coffee machine made up of?
Italians would call the upper layer "Crema", and this unique and rich layer of Crema can only be produced by an espresso machine. The key lies in pressure. The espresso machine generates a 9 bar water pressure to "squeeze" the coffee powder. Because the pressure of carbon dioxide in the coffee powder is too high, the water becomes supersaturated with carbon dioxide, so the carbon dioxide cannot be released and is directly integrated into the coffee liquid. During the extraction process, the fat in the coffee will be emulsified, and these fats will be wrapped in carbon dioxide. Since it is lighter than water, everything will gradually stratify, and golden yellow oil will emerge on the surface, which is very beautiful.
So this golden and delicate coffee oil is formed by the insoluble oil of coffee wrapped with carbon dioxide. So how do you make espresso have a beautifulWhat about Crema?
From the perspective of the front street, high-quality Crema is golden yellow, with a delicate surface and uniform color. It shakes like a creamy smooth product and has an obvious wall-hanging feel. It not only makes the concentrate have a good visual effect, but also enriches the taste and aroma when tasting, and protects the flavor of the coffee. It is also more conducive to the fusion of latte art and the supporting pattern when making hot milk coffee. Perhaps these are the reasons why people go to great lengths to pursue a perfect Espresso!
Based on the usual extraction experience, Front Street believes that it is actually very simple to obtain rich Crema. First of all, when buying coffee beans, you need to choose beans with high fat content and sufficient carbon dioxide, such as medium-dark roasted beans, in the tasting period (45-60 days), or fresh Italian formula beans with a certain proportion of robusta. For example, on the bean menu of FrontStreet Coffee, the two espresso coffees, "Front Street Commercial Blend" and "Front Street Classic Blend", are mixed with a small amount of Roman beans, making it easy to concentrate and show beautiful oil.
Selecting the right coffee beans requires fresh grinding, stable high temperature, sufficient extraction pressure, and reasonable extraction parameters. Only by meeting these key factors can you get Espresso rich in dense oil.
In general, the fresher the beans, the darker the roasting degree, the greater the pressure on the equipment and the more stable the performance, the better the expression of coffee oil. Next, we will analyze the specific situation in detail. Front Street will teach you how to judge the quality of Espresso by observing the form of oil, so as to solve various common problems in extraction.
No oil at all, or the oil is thin: the problem is most likely caused by the beans being left out for too long (including improper storage and pre-ground coffee beans). The longer the coffee beans are stored, the more carbon dioxide is lost due to gas exchange with the air, and the less coffee oil is finally present. Secondly, the pressure of the coffee machine is too low, the temperature is too low, the grinding degree is too coarse, and the tamping force is not enough... these are also the causes of too little grease.
White fat: If the concentrate you extract has a good fat thickness, but lacks golden color, the overall taste will be sour. Then, it is probably because of the use of lightly roasted beans. For example, if you use Pour over(V60) beans that mainly express the sour flavor to make Italian style, it will easily show an unpleasant sourness due to insufficient extraction, accompanied by white fat.
Grease is rough and foamy: This kind of concentrated crema tends to last very short and dissipates quickly. This is caused by the fact that the coffee beans are too fresh. Freshly roasted beans contain a large amount of carbon dioxide. When a large amount of gas is pressed into the coffee liquid, the emulsified oil cannot wrap the gas and it will easily disintegrate.
Grease agglomeration: This kind of concentrated milk will generally appear in the shape of an obvious "pimple" when shaken. The oil on the surface is uneven and has poor fluidity, just like milk froth that is too old and difficult to push away and fuse.
You can now buy the above coffee beans online at the Taobao store “FrontStreet Coffee” (前街咖啡). FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou, China, and its Guangzhou retail shop sells coffee beans only. The shop carries dozens of coffee beans from different origins around the world, including carefully selected single-origin beans for V60 pour-over and espresso. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers.
The FrontStreet 2013 Yunnan coffee beans sold in the store come from the Typica variety grown at FrontStreet Coffee’s own plantation in Yunnan. The name comes from the year the brand and the plantation were founded. You can buy these beans from China’s Yunnan origin at the Guangzhou shop and at FrontStreet’s Taobao store.
FrontStreet coffee beans are freshly roasted within 5 days and deliver consistently excellent quality and great value. Orders placed before 17:00 are shipped the same day, and most areas within Guangdong Province receive them the next day.
FrontStreet Coffee Taobao store: https://qianjiecoffee.taobao.com
Or search for “前街咖啡” (FrontStreet Coffee) on Taobao
Important Notice: FrontStreet Coffee has moved to a new address: 315, Donghua East Road, Guangzhou (coffee beans only)
Tel: 020 38364473
