Whenever Front Street is brewing Pour over(V60) coffee, as long as the bulge in the powder bed is relatively large during steaming, there is a certain probability that customers and friends will ask: "Why is the bulge in the powder bed not so big when I make coffee?"This is a topic often shared on Front Street! To be fair, although the size of the bulge during steaming does not directly reflect the taste of the coffee, we can read a lot of other information from its state, such as the state of the coffee beans or the parameters used during brewing, because it is they that determine the bulge of the powder bed.So today Front Street will share with you how these factors affect the degree of bulging, and why, the size of the bulging cannot directly reflect the taste of coffee.1. Freshness and roasting degree of coffee beansFirst of all, we need to know that the main cause of the bulging phenomenon when steaming coffee is carbon dioxide. Coffee beans will accumulate a large amount of carbon dioxide during the roasting process, and this carbon dioxide will be slowly released after the coffee beans are roasted. If the ground coffee comes into contact with hot water, the emission of carbon dioxide will be greatly accelerated.What we call steaming is a step specifically designed to release carbon dioxide. By using a small amount of hot water to wet the coffee powder, the carbon dioxide will quickly transfer outward, which allows the subsequent hot water we inject to better extract the flavor substances in the coffee.In the process of carbon dioxide emission, the surface tension of water molecules and the capillary action between coffee powder particles will jointly weave an airtight "barrier". The reason why it is airtight is because this "barrier" will "trap" carbon dioxide in the powder bed and cannot be discharged. Due to being "imprisoned", carbon dioxide will accumulate more and more in the powder bed, and then the powder bed will bulge bigger and bigger like a balloon due to the increase in gas in the body. And this is the principle of powder bed bulging.Through this principle, we can know that the reason for the bulge in the powder bed is mainly affected by carbon dioxide, and the carbon dioxide content of the coffee beans is one of the factors that determines the size of the bulge. When the extraction parameters remain unchanged, the more carbon dioxide contained in the coffee beans, the greater the degree of bulging during steaming; the less carbon dioxide, the smaller the degree of bulging.In fact, it is easy to understand, because the more carbon dioxide content the beans have, the more carbon dioxide will be emitted during steaming, so the bulge of the powder bed will naturally be improved due to the increase in carbon dioxide. There are two main factors that determine the carbon dioxide content of coffee beans: roasting degree and freshness. When the coffee beans are fresher/roasted darker, the carbon dioxide content will be more, and vice versa.So if the coffee beans we use are roasted dark enough or fresh enough, then we can see relatively larger bulges during steaming.But careful friends should have discovered that Front Street has always emphasized a premise in the above, and that is "under the condition that the extraction parameters remain unchanged." Why? --Because extraction parameters are another factor that affects drum size!2. Extraction efficiency during brewingTo be precise, it should be extraction efficiency! When we use a higher extraction efficiency when brewing, the substances in the coffee will be dissolved faster, including carbon dioxide. Therefore, the higher the extraction efficiency, the faster the carbon dioxide is released, and at the same time, the greater the degree of bulging of the powder bed.The reason why many friends' powder beds cannot make big bags when steaming is because the extraction efficiency during steaming is not high enough, which prevents the carbon dioxide from being released quickly in a short period of time. So even if the beans used are very fresh or roasted very darkly, the degree of bulging is not that outstanding.What everyone needs to know is that although there are many factors that affect extraction efficiency, such as time, grinding, stirring, water temperature, etc. But when steaming, the main factors that affect the size of the drum are the water temperature and the thickness of the grinding. The higher the water temperature and the finer the grinding, the greater the bulging will be during steaming, and vice versa.To sum up, everyone can know that the main factors that affect the size of the bulge when steaming the coffee powder bed are the freshness and roasting degree of the coffee beans, as well as the extraction efficiency during brewing. But again, the size of the bulge does not directly reflect the taste of the coffee!For example, the Front Street Divide Manor·Xijiao in the Front Street bean menu. Last time, Front Street used the same parameters to brew and roast the Xizhua for 2 days and the Xizhua that was roasted for 25 days to make a comparison for customers. Although fresh hija that has been baked for 2 days will have a larger bulge than hija that has been baked for 25 days, its flavor is not as rich.Although the bulging degree of hope Zhao baked for 25 days is small when steamed, its layers are rich and prominent. Taking the flavor as an example, in addition to the flavors of grape, passion fruit, apricot, and wine, Front Street also tasted some floral aroma and a more rounded fruit wine aroma. The reason for this difference is that too much carbon dioxide hinders extraction, which is often mentioned in the front street. However, since it is not the main content of this article, I will not go into details here.Therefore, it is best not to use the size of the bulge in the powder bed during steaming as a measure of the taste of coffee, because this does not directly reflect the taste of the coffee. It reflects the status of the coffee beans and brewing parameters mentioned above. It would be more appropriate to regard the degree of bulge as a "file" reading of these two pieces of information~
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
