Recently, a friend came across this post on the Internet: "If you steam for too long, it is easy to brew under-extracted coffee."Obviously, this statement goes against our long-standing understanding of steaming. Because as we all know, the purpose of steaming is to expel the carbon dioxide in the coffee powder, allowing us to more easily dissolve the flavor substances in the coffee powder. To put it simply, it is a way to improveExtraction ratesteps.Especially for coffee with higher freshness, longer steaming will help to discharge more gases that hinder extraction. So logically speaking, the extraction rate should be further improved. How can it lead to insufficient extraction?So this friend came to the store with doubts and asked about the truth about the incident on Front Street! According to this friend, there are two more credible explanations he saw from these posts: one is that steaming for too long will cause the water temperature in the pot to drop, and the drop in water temperature will affect the extraction efficiency, resulting in the possibility of insufficient extraction;Another theory is that because all the carbon dioxide is emitted, the speed of launching into the water will be much faster. The contact time between coffee and water is reduced, which in turn results in reduced extraction efficiency, making the coffee more likely to be under-extracted.So is this really the case? Today Front Street will verify it through a set of experiments!The content of the experiment is very simple. Front Street will brew two pots of coffee using different steaming times, and then measure and compare their taste and extraction rate to see if the extraction rate will really decrease.But if you are a friend who often reads Front Street’s tweets, you should know that Front Street just shared an article a while ago about the difference between steaming for 30 seconds and steaming for 60 seconds. In that article, Front Street brewed three groups of coffee for comparison. Although the beans used in the three groups are different in terms of roasting degree and freshness, the results are without exception. The coffee group with a longer steaming time will have a higher extraction rate than the coffee group with a shorter steaming time.Some friends may think that this is the result of the difference in steaming time being insufficient. Therefore, today, Front Street will further widen the gap in steaming time, using a steaming time of 30 seconds and a steaming time of 1 minute and 30 seconds for comparison.(No longer necessary). Let’s see if the facts are true as the rumors say. If the steaming time is too long, the extraction rate will actually decrease!The coffee beans chosen for this experiment are the Yirgacheffe Guo Ding from the Front Street bean list. It has been roasted for 10 days. It is in the best tasting period and retains a certain amount of carbon dioxide. It can well show the impact of different steaming times on coffee. The extraction parameters are as follows:Amount of powder used: 15.6gAmount of water used: 225mlGrinding degree: 80% screening rate of No. 20 meshBrewing water temperature: 92°CBrewing method: three-stageThe brewing process is skipped. Except for the time and steaming time, the other steps and parameters are all the same. Let’s look at the results directly.In terms of taste, the diced fruit that has been steamed for 30 seconds has a very good performance. The taste is very balanced, the texture is smooth, the flavor is outstanding, and it has the aroma of white flowers, lemon, berry, and a long aftertaste. The performance of the diced fruit that has been steamed for 1 minute and 30 seconds is as expected by Front Street. It is overall better than the diced fruit that has been steamed for 30 seconds.(a little bit). Although the difference is not big, its flavor will be more prominent in comparison(a little bit), the taste will be fuller(a little bit)。Front Street verified this fact by measuring extraction rates. The concentration of diced fruit steamed for 30 seconds is 1.48%, and the extraction rate is 19.46%; while the concentration of diced fruit steamed for 1 minute and 30 seconds is 1.53%, and the extraction rate is 20.13%, which is slightly higher than the former.Then Front Street also measured the water dispensing speed and water temperature during brewing. The result was that the water dispensing speed was the same. The two sections of hot water injected later finished flowing out at the same time, and there was no acceleration due to excessive exhaust gas. The same is true for the water temperature.The initial water temperature in the two pots of coffee was the same at 92.6°C, but when the water was filled in the second stage, their water temperatures were 91.4°C.(30 seconds)and 90.9°C(1 minute 30 seconds). It can be seen that although the steaming time differs by one minute, the temperature difference is only 0.5°C, so it will not have a big impact on the extraction.
From these results, we can see that the extraction rate has not decreased due to the increase of time. On the contrary, the extraction rate has been slightly improved.So, the conclusion is that steaming for too long will not lead to insufficient extraction?Neither. Under certain circumstances, steaming for too long may cause the coffee to be under-extracted, but these situations are usually a bit extreme.For example, the steaming time is longer than the 1 and a half minutes, the ambient temperature is lower than it is now, or the heat preservation performance of the hand brewing kettle is not that high, etc... In these cases, the water temperature after steaming will be much lower than the preset, which will lead to the extraction efficiency not being that high, and the final extraction rate of the coffee will be lower than when steaming for 30 seconds.However, this only makes the extraction rate of the coffee lower than that of steaming for 30 seconds, rather than under-extraction. You can calculate the extraction rate measured from the front of Front Street. Even if there is a difference, the difference will not be so big that the coffee will be under-extracted.If there is really under-extraction, in addition to the steaming time being too long, the most likely reason is that the original brewing parameters themselves did not fully extract the coffee, so if the water temperature is slightly lower, the coffee will easily be under-extracted.To sum up, we can know that steaming for too long will indeed have an impact on the extraction rate of coffee, but whether this impact is good or bad must be judged based on the specific situation.
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
