A surprise question from Front Street: When you pour coffee powder into a filter cup and a scene like the picture below appears, what will you choose to do?I believe that most of my friends, like Front Street, will choose to flatten the unevenly distributed powder bed by tapping the filter cup.
. This isn’t just to make it look better, but it’s also believed that smoothing the powder bed allows for more even extraction.That is indeed the case! Compared with an uneven powder bed, a flat powder bed makes it easier for hot water to extract evenly, making it easier for us to brew a cup of delicious coffee.but ! yes ! The method of flattening the powder bed is also very particular. If you don't pay enough attention, the coffee we brew after flattening the powder bed may not taste as good! For example, when we tap very frequently, it may be because of "brazil nut effect” appears and affects the extraction.The so-called "Brazil nut effect" means that when we apply external force to a container containing particles of different sizes by shaking or tapping under normal circumstances, a phenomenon will occur in the container: larger particles will gradually rise to the surface, while smaller particles in the container will settle to the bottom.Front Street often shares this effect, because this phenomenon is very common in coffee! Not only does it work with coffee beans, it also works with coffee powder!The coffee powder ground by the grinder is not uniform in size, there are both large and small particles. When such differences exist, it will lead to the Brazil nut effect! When we tap the filter cup, the coffee powder with smaller particles will accumulate at the bottom of the filter cup, and the coffee powder with larger particles will concentrate on the upper layer. This will easily lead to two extraction problems:When the coffee powder with smaller particles accumulates at the bottom, it will be difficult for the hot water during steaming to evenly wet all the coffee powder, which will affect subsequent extraction.Because the gaps between the small particles will be narrower, especially after frequent tapping, the "connection" between the particles will be closer, and the flow space of hot water in the coffee powder will be greatly reduced. As we all know, water is inert and will flow where it flows easily. Therefore, when the powder bed at the bottom is very compacted because it is filled with small particles of coffee powder, hot water will first flow to the edges of the filter cup and other spaces with large gaps and easy flow.If enough water is injected, then this effect is completely negligible. For example, in the main extraction stage of Pour over(V60) coffee, because the amount of water injected is enough, there is no need to worry about being affected by the channel effect during extraction like espresso coffee.But it’s different when steaming, because we don’t use much water when steaming(Usually use twice the amount of water as powder), so when the powder bed is too compacted, a small amount of hot water will be difficult to wet all the coffee powder due to inertia, because the hot water will run to other places where it can easily flow after contacting the compacted powder bed.Front Street has done many tests for this, and found that when we use a conical filter cup that can increase the thickness of the powder bed and high-density coffee powder, tapping the filter cup multiple times can easily lead to the hot water not being able to fully wet the coffee powder. When the steaming time is up and the coffee powder is dug out, you can always see that the coffee powder at the bottom is still dry.If this happens, the coffee powder will not be able to fully exhaust during steaming, and will not be able to release a sufficient amount of flavor substances during the extraction process. As a result, the coffee we finally brew will not taste so good! Because of the decrease in extraction rate, the flavor is not as prominent and the taste is not as full.Secondly, excessive tapping can easily lead to over-extraction of coffee! The reason is also very simple. As mentioned before, the Brazil nut effect will cause small particles of coffee powder to settle downwards. Of course, these small particles of coffee powder also include ultra-fine coffee powder. When we beat these ultra-fine powders to the bottom, they will easily block the pores of the filter paper!The more times/harder you tap, the higher the chance of clogging. When the filter holes of the filter paper are blocked, the space for water to flow will be further reduced, which will extend the coffee extraction time. Excessively long extraction time will lead to higher extraction efficiency, and eventually we will easily brew a cup of over-extracted coffee.The above are the negative situations that may occur after flattening the coffee powder. I believe some friends on Front Street Street have something to say at this time. In summary, when we encounter uneven coffee powder, can we only use other methods to level it instead of flattening it?Of course not! You can also tap, but it is best not to tap the filter cup too many times or too hard, so that too much coffee powder will not migrate, and naturally the above-mentioned negative situations will not occur. Of course we can also choose other ways to level it, but the principle is the same, just don’t be too aggressive~
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
. This isn’t just to make it look better, but it’s also believed that smoothing the powder bed allows for more even extraction.
