What is the difference between deep roasting and light roasting? Coffee brewing secrets are open!

Often some friends will ask the best brewing parameters of Qianjie after buying beans in the store online, in order to reduce the chance of turning over during brewing and make delicious coffee directly. Then Qianjie will introduce the characteristics of the beans to the guests and share the best cooking parameters. For example, because this bean is shallow baked, the water temperature should be relatively high, about 90 °C ~ 93 °C, and then the grinding should be relatively fine; or, this bean should be deeply baked, so the water temperature should be relatively low, about 86 °C ~ °C. then grind it thicker. The time and powder / water ratio are the same, both controlled at about 2 minutes and 1:15.

So yesterday, a friend wondered: "Why is the water temperature of shallow baked beans higher and finer ground, while that of deep baked beans is lower and thicker?"

How is the brewing framework for deep and shallow roasted coffee developed?

As Qianjie said, this is based on the characteristics of the two! If we want to make a good cup of coffee, then we have to find the best brewing formula to match the current coffee beans. Time, proportion, grinding and water temperature are the four important parameters to construct the formula. Then in these four parameters, the main parameters we adjust are water temperature and grinding. (because the ratio of powder to water mainly determines the concentration of coffee, there is generally a fixed range of ratio. Because the time can not be directly controlled, it is fixed as a benchmark to measure the appropriateness of other parameters, so they are not the main adjustment objects) the characteristics of shallow roasted coffee beans are high density and difficult to extract. Because the baking time of beans is relatively short, coffee beans do not expand too much and retain a relatively high density; deep-baked beans are just the opposite! Because the baking time is relatively long, the coefficient of expansion of coffee beans is larger, so the density is not so high.

And the density determines the difficulty of extraction! Shallow baked beans are more difficult to extract than deep-roasted coffee beans because the coffee powder is denser and the hot water is more difficult to penetrate. At the same time, the high density also leads to a denser structure of the powder layer, which is not conducive to the full contact between coffee powder and water. Therefore, Qianjie will use a relatively higher water temperature to improve the extraction efficiency when brewing shallow roasted coffee beans, so that the coffee can be fully extracted.

Deep-baked beans are on the contrary, because the expansion rate is higher, the weight is lighter and the water absorption rate is faster, the flavor substances in the coffee will be more easily dissolved. Therefore, Qianjie used a relatively low temperature to reduce the extraction efficiency and avoid the risk of over-extraction of coffee.

Then, the degree of roasting of coffee beans will also affect the toughness of coffee beans! When the coffee bean is less roasted, the toughness is higher and the brittleness is lower; when the coffee bean is roasted more deeply, the toughness is lower and the brittleness is higher. The toughness / brittleness of coffee beans determines the quality of coffee powder during grinding. Under the same grinding, the beans with high brittleness will grind more fine powder and larger surface area! On the other hand, the beans with low brittleness and high toughness will grind out relatively more uniform particles, less fine powder and less surface area.

In fact, it's easy to understand, just like breaking cookies! Biscuits with high brittleness can be broken as soon as they are broken, and a lot of tiny crumbs will break out at the same time. And if we break cookies with less brittleness, there will be much less debris when breaking cookies. The same applies to the grinding of coffee beans. In other words, under the same grinding, the total surface area of deep baked beans will be larger than that of shallow baked beans, and the screening rate will be higher. This is why the degree of grinding required for deep and shallow baked beans is different! Because deep-baked beans need relatively thicker grinding to reduce the surface area and fine powder to avoid over-extraction due to high extraction efficiency or blockage caused by fine powder during cooking, while shallow baked beans need to use finer grinding to increase the surface area and increase the extraction efficiency (both relative).

The above is the reason why it is necessary to make a difference between deep-boiled and shallow baked beans in grinding and water temperature. In addition to the parameters, the tools and techniques used in Qianjie cooking are different! Let's start with the tools. Because the thickness of grinding and the density of coffee powder affect the speed of launching, Qianjie will also use filter cups with different flow rates to help control the extraction time of coffee. When brewing shallow roasted coffee, because of the high density and fine grinding of the coffee powder, the resistance of the powder bed is increased, which leads to slow launching. Therefore, Qianjie is equipped with a fast-flow V60 filter cup to increase the launching speed and avoid over-extraction of coffee caused by the slow flow rate; while when brewing and roasting beans, because of the low density of coffee powder and coarse grinding, it needs a slower flow rate Kono filter cup to slow down the launching speed to ensure that the coffee can get enough extraction.

And then there's water injection! Because most of the light-baked coffee powder is heavy, the powder bed is difficult to be lifted by the current. Therefore, Qianjie usually uses a small flow of water to inject water when extracting this kind of coffee. Avoid excessive water flow over the powder bed, the concentration is too low, the coffee taste is too light. This article is a good example of "how to make light roasted coffee?" ", but it is only suitable for coffee beans with high density, and other beans can be cooked according to the conventional three-stage style.

Then when brewing deep-baked coffee beans, because the coffee powder is lighter, the powder bed can be easily raised to form a powder wall. So Qianjie usually uses a flood to inject water, build the powder bed, and then focus on extracting the coffee powder at the bottom to make the extraction more uniform!

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