4 Key Factors Affecting Coffee Extraction Rate
Contents:
1. Coffee-water ratio.
2. The key factors affecting coffee extraction rate
Today, if you want a light-bodied coffee, you can reduce the extraction rate; or if you prefer a full-bodied flavor, you can increase the extraction rate. Understanding the coffee extraction rate is essential! Knowing the key factors that affect coffee extraction, you can easily make a delicious cup of coffee anytime.
Coffee-water ratio.
The two most commonly heard terms in pour-over coffee are extraction rate and coffee-water ratio. The two are interdependent and affect the taste of hand-drip coffee. The coffee-water ratio, or the ratio of coffee to water, is most commonly used at 1:15, i.e., using 20g of coffee powder and 300g of hot water. If this is the concentration we usually drink, we can change the taste by reducing or increasing the extraction rate, resulting in a light-bodied or full-bodied flavor, respectively. Each bean has unique flavor characteristics, and the adjustment we refer to here is to adjust within the existing flavor profile of the same bean, not to create new flavors that do not exist.
│ Further reading: The Golden Ratio for Perfect Hand-Drip Coffee
The key factors affecting coffee extraction rate
The four key factors affecting coffee extraction rate are water temperature, grind size, time, and roast degree. Although the brewing method also affects coffee extraction, it has too many variables to control, so we will focus on these four elements that are relatively easy to master. The following simple diagram illustrates the four factors, ranked from easiest to most difficult to master, with four arrow-shaped graphics. The farther right, the higher the extraction rate, and the farther left, the lower the extraction rate.
Water temperature
Under other unchanged conditions, the higher the water temperature, the faster the volatile aroma and water-soluble substances in the coffee will be released. Conversely, the lower the water temperature, the less able it is to extract these substances. If the coffee tastes bitter or strong, try lowering the water temperature. If the coffee tastes watery or bland, it means that there are still many soluble substances left in the coffee powder, so you can increase the water temperature when brewing next time.
Grind size
Under other unchanged conditions, the finer the grind size, the larger the contact area between the coffee powder and hot water. One gram of coffee beans usually contains about 7-8 beans (using Ethiopian beans as an example), but after grinding into pour-over particles, each gram contains about 700 particles. The contact area with hot water thus increases many times over. Therefore, the finer the grind size, the more particles, and the higher the extraction rate. Conversely, the coarser the grind size, the lower the extraction rate.
Time
Generally, the most commonly used and best time to control is 2 minutes and 30 seconds, with a 30-second blooming time. If you want to increase the extraction rate, extend the time, and if you want to decrease the extraction rate, shorten the time. However, when changing the extraction time, multiple factors usually change simultaneously, especially when extending the time. For example, the water temperature of the pour-over kettle will decrease due to the longer time, the coffee powder will easily absorb water, causing the filter to clog, etc. Shortening the time may result in insufficient extraction. Therefore, the first two factors mentioned above are relatively easier to control and the brewing time can be adjusted accordingly at the end.
Roast Degree
The darker the roast degree, the more the cell pores of the coffee beans expand, making it easier for hot water to extract soluble substances. Conversely, the lighter the roast degree, the lower the extraction rate. Coffee beans are made up of millions of pores. Generally speaking, a regular coffee bean contains 4.5 million pores, with each pore measuring approximately 50-70μm. Coffee flavor comes from soluble substances that exist within these pores. Water can only extract soluble substances from the pores it can come into contact with. Grinding coffee increases the number of pores that water can enter. Since this variable has already been determined by the roaster and cannot be adjusted during the pour-over brewing stage, we need to understand the relationship between roast degree and extraction rate in order to adjust the extraction rate using the aforementioned three variables.
Master the four key elements of coffee extraction: water temperature, grind size, time, and roast degree, and let Justin Coffee help you brew a great cup of coffee. Check out our pour-over brewing tips and experiment with adjusting these four variables - soon, you'll be a coffee brewing pro right in your own home!
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