Why is the flow rate of hand-brewed coffee sometimes fast and sometimes slow? Relationship between coffee bean hardness and altitude roasting method

If you often read Qianjie's articles, you should not be too unfamiliar with the brewing time of "2 minutes". It is a reference value based on countless extraction experiences in the past and can help us determine the speed of the flow rate.

Recently, a friend bought a bunch of different types of beans at a Qianjie store and asked curiously: He extracts them according to the parameters we provided every time, but why does some coffee beans flow very fast when brewed? In less than 2 minutes, all the liquid has been dripped into the pot; some coffee beans are like "enemies", water will accumulate for a long time every time they are flushed. I don't know if the water is blocked well or if the water is over.

Let's first take a look at the main factors that affect the flow rate of different coffee beans:

1. Baking degree

The shallower the roasting degree, the shorter the heating time of the coffee beans and the higher the internal density, which leads to a firmer structure of the powder layer, and the smaller gap through which hot water can flow during extraction, which makes it easier to be blocked; In addition, the texture of lightly roasted coffee beans is more crispy, and at the same grinding scale, more extremely fine powder will "burst" out, which is one of the important reasons why lightly baked beans by hand are always "flooded."

As the degree of roasting deepens, the coffee beans continue to expand, and the density of the internal structure becomes lower. The ground powder layer is loose and uniform, providing a larger gap for the hot water, which allows the coffee liquid to pass smoothly through to the lower pot. Therefore, the overall extraction time of medium to deep roasted beans will be better controlled than that of lightly roasted beans.

2. Treatment method

Water washing, sun exposure, and honey treatment are classified as the three major traditional treatment methods. Coffee beans have not received much external interference during the processing process, so they retain their original density structurally, while the opposite is "non-traditional treatment". Method ", a typical representative is anaerobic fermentation process.

The anaerobically treated coffee beans will be temperature-controlled fermentation in a sealed barrel. The decomposition rate of pulp and pectin will be reduced, which will prolong the fermentation time, and then allow the coffee beans to derive more fruit flavor and fermented aroma. Compared with the three traditional coffees, the anaerobic process will reduce the tightness of the coffee bean cell walls, so the internal structure will become very loose after roasting, and it can easily and smoothly rotate when grinding.

Qianjie Cizao Coffee using double anaerobic sun exposure is a very successful development. The low-temperature fermentation step greatly improves the sweetness of Cizao and makes the aroma of passion fruits, grapes, and dried blueberries clearer. Although Qianjie Xizhao also uses medium and light baking, it can be found that the water discharge rate is significantly faster than that of ordinary sun-cured beans and washed beans during extraction, and it is easy to extract insufficient if you are not careful.

3. Planting altitude

In the introduction of all single-product coffee beans, the origin, manor, processing method, altitude, variety... These basic information are often marked. Affected by purchase demand, few people will pay attention to the reference indicator of "planting altitude." But Qianjie wants to tell you that if you want to comprehensively analyze the flow rate problem, the answer will be hidden if the altitude is uncertain.

Friends who have studied geography know that for every 100 meters increase in altitude, the temperature drops by 0.6 ° C. Therefore, the higher the altitude at which coffee trees are planted, the lower the temperature will be, and the growth and maturity of the fruits will also be delayed. This not only helps coffee beans store more aromatic precursors and also allow it to form higher hardness.

For example, in the Ethiopian producing areas that Qianjie likes very much, most of their single products are produced at an altitude of more than 2000 meters, such as Qianjie Guodingding (2100 meters), Qianjie Guixia Village Hongbiao (2069 meters), Qianjie Huakui (2350 meters) and other medium-to-light baked beans, which mainly focus on floral and fruit acids, cause the flow rate during brewing to slow down due to their high hardness. Coffee that is severely "overtime" will either be over-extracted or have unclear flavor.

After talking about the reasons, let's analyze the solution again:

Now that everyone knows that the hand-flushing flow rate of different coffee beans is affected by the above three aspects, then to keep the extraction time at the ideal value, you only need to analyze the specific situation.

Flow rate is too fast: anaerobic treatment, deep baking

If you brew anaerobic coffee beans at an abnormally fast rate and have little aroma, there is a high probability that there is insufficient extraction, so it is best to directly adjust the grinding degree. Qianjie coffee usually only uses 2 to 3 grinding scales. Light roasting is the finest and deep roasting is the thickest. In order to lock hot water, anaerobic coffee is 0.5 squares thinner than lightly roasted beans (hand grinding can be adjusted by 1 to 2 squares). At the same time, in order to make the extraction time more sufficient, Qianjie will control the water flow to be smaller when injecting water, so that the powder layer does not need to be lifted too high. In this way, the flavor of the brewed coffee will be stronger and fuller.

When you brew deep-baked beans, the time is always less than 1 minute and 40 seconds. The taste lacks mellow quality. The problem is likely to be the lack of support from the end. Considering that deep-baked beans contain more scorched sugars, and adjusting the grinding degree will easily release too much bitterness, so instead, Qianjie suggested dividing the total water volume into four sections. After steaming, use small water throughout the process. Inject in circles, friends with conditions can replace slow-flow filter cups such as KONO, cake cups, and Kalita, which will lengthen the overall soaking time. If you feel that you are overextracting, lower the water temperature by 1~2 ° C and try again.

The flow rate is too slow: shallow baked beans at high altitudes

On weekdays, Qianjie recommends using a combination of "high water temperature, fine grinding, and fast flow rate" when flushing shallow baked beans. At this time, fine grinding is the main culprit for the slow flow rate. There are two solutions to the problem here, either adjust the rough grinding degree, or change the technique, and then reduce the water temperature.

If the time you spend every time you make shallow baked beans is exaggerated, and the tea is mainly astringent, thin, and irritating and sour when you drink it, Qianjie recommends that you adjust the grinding scale to 3 to 4 squares thicker, which can directly change the size of the particles., and reduces the distribution of extremely fine powder, while also reducing the contact area with hot water, allowing the flow rate of coffee liquor to be faster.

Without changing the degree of grinding, you can also rely on adjusting the technique to speed up the light roasting coffee. Generally, after steaming on the front street, the winding range is continuously increased when injecting water until the powder layer is piled up to 4/5 of the filter cup. The purpose is to allow large particles to first drive the fine powder to be distributed on the edge of the filter cup for subsequent injection. The hot water provides a smooth channel, and the third section of hot water will continue to be injected until all the coffee liquor is almost exhausted. This will reduce the probability of clogging and be more conducive to subsequent uniform extraction.

Finally, if adjusting the grinding degree and technique cannot improve the water accumulation problem of hand flushing, Qianjie recommends that you not interfere with the brewing time first, but try the effect by lowering the water temperature. For example, whenever the Qianjie Guixia Village gold label is brewed, it is easy to over-extract due to "overtime" if fine grinding is used. Therefore, Qianjie has an idea to adjust the water temperature to 86 ° C and finish the extraction in 2 minutes and 32 seconds. The coffee not only has no negative taste, but also shows rich aroma of fresh citrus and black tea. It can be seen that there is no universal formula for hand flushing, only appropriate extraction management.

FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou China, selling freshly roasted beans from its own farm in Yunnan as well as dozens of carefully selected single-origin beans from around the world for both pour-over and espresso. The products deliver consistently excellent quality and great value, with shipping within 24 hours. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers, and the beans are now available online at the Tmall 。

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473