What is the channel effect? What are the effects? How to judge whether espresso is too good?

Professional coffee knowledge exchange more coffee bean information please follow the coffee workshop (Wechat official account cafe_style) A good espresso is the basis of all espresso, espresso can magnify the advantages of coffee beans, bad concentration will of course infinitely magnify the disadvantages. So how to make a cup of Italian concentrate correctly has become the only way for baristas and even coffee lovers.

Today, the editor is here to discuss with you about the common problems in Italian concentrated extraction-how to judge whether Italian concentrated is too good or not?

Before starting, the editor would like to emphasize that the production of espresso must be good, because the use of poor quality or unstable coffee beans, good coffee is out of the question. The coffee beans we use are all self-baked and strictly selected and proportioned Italian beans. Baristas and bakers have a close relationship, and mutual understanding is an important factor in showing coffee flavor.

Let's first take a look at the performance of sensory Italian concentrated extraction deficiency, ideal extraction and excessive extraction.

1. Insufficient extraction

Insufficient extraction means that there are not enough coffee powder substances brought out by water, and there are many residual substances in coffee powder, which can increase the flavor of this cup of coffee.

Imagine a cup of espresso, or ristretto, with a sour taste, a lack of sweetness, a strange salty taste and a disappointing short finish. These four characteristics are obvious signs of insufficient extraction.

2. Ideal extraction

The concentrated aroma of the ideal extract is overflowing, the acid quality is balanced and brings a positive feeling, the flavor is rich and varied, and the finish is long. As we usually adjust the concentration, will have sweet chocolate, caramel, nut cookies, the aftertaste will have berries, ripe fruit and other flavors.

Third, excessive extraction

The over-extracted coffee represents bringing out too much soluble matter in the coffee, and the result of this extraction is a bad flavor.

Imagine an espresso that takes 40-50 seconds to extract. The coffee is bitter, dry and hollow, and often smells of wood, traditional Chinese medicine and even rubber. This is the most obvious feature of over-extracted coffee.

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The above is the sensory Italian concentrated taste, and how to look at it visually:

The concentration of light color and thin oil can basically be judged as insufficient extraction.

The color is very dark and the color of the oil on the surface is inconsistent, which can be judged as excessive extraction.

The appearance of grease spots on the surface can be judged to be caused by partial overextraction caused by perforation.

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The above are some conventional methods to judge whether Italian concentration is ideal or not. Insufficient extraction can be easily judged, while ideal extraction can not be found. Excessive extraction is a problem that occurs in most concentration-due to piercing, different thickness of pressed powder, uneven filling pressure, etc., part of the water will concentrate in a certain position of Italian to extract more substances-water is an inert substance. Will find the passage from the place with the least resistance. Therefore, to eliminate the problem that the extraction time is too long, the over-extraction of Italian coffee is caused by the "channel effect".

Channel effect

When you are in the extraction of Espresso, if the flow rate suddenly increases, there is a color uneven oil (crema), that is, pressed powder perforation, resulting in a "channel effect", the "channel effect" will make the flow more easily through the cracks and uneven coffee extraction, resulting in a cup of bad Espresso. The common reasons are uneven cloth powder, uneven force when pressing powder, or too much powder (too much coffee powder).

The following editor to tell you a more simple and direct way to determine whether the production of Italian concentration has not been outstanding, but also can accurately determine from which point of pressed powder to form a channel to cause over-extraction! You don't have to smell or drink, just take a look!

Don't talk too much, above!

Did you see that? The picture shows the powder bowl after knocking out the pressed powder as soon as the coffee is made, and the coffee oil remains on the powder net, which is the proof of over-extraction; if your coffee is perforated and extracted, the "spot" of the residual oil is where the water forms the channel!

Why is this? Let's take a look at the schematic diagram of hand-flavored flavor release before, which is similar to espresso extraction.

In the first part of the extraction, the sour taste will be released first, then the sweet taste, and finally the bitter taste.

Sweet and sour flavor molecules are small molecular weight compounds, which are more easily extracted by hot water, while bad flavors such as bitterness and miscellaneous taste have a relatively large molecular weight and will only be extracted in the middle and later stage. and because the bitter and mixed flavor molecules with large molecular weight will increase rapidly with the amount of extraction, the flow of water is faster without the resistance of the coffee content at the end of the extraction, so the coffee liquid suddenly "whitens". Some of the over-extracted coffee liquid will remain in the powder bowl, so when you see that the more coffee liquid retained and the whiter the color, the more serious the Italian concentrate you have made.

To correct the uneven problem of concentrated extraction, it is necessary to adjust the degree of grinding, powder distribution, filling and pressure, and do not ignore the coffee machine. If there is a problem with the cooking head or the water distribution network, resulting in the flow of water can not fall evenly, it will also cause the passage to pass through the extraction, at this time, you should find a professional to carry out maintenance.

Essential skills for baristas | Powder hammer design, powder pressing skills, powder distribution skills

That's what we're talking about today. Have you raised your posture?