Espresso Extraction Rate｜What is Gold Cup Extraction? What factors affect the flavor of espresso extraction? How to calculate coffee extraction rate?

Amount of coffee powder

The amount of powder is roughly determined by the size of the bowl. It is not recommended to use much less or more powder than the size of the bowl.  The amount of powder will affect the density of the powder cake. Under the same filling pressure, too little powder will be sparse, resulting in a faster flow rate and insufficient extraction. On the contrary, the density will be denser, the flow rate will be slower, and it will even be difficult to extract the coffee liquid. The amount of powder used by FrontStreet Coffee is: 7-9g for a single concentrate and 18-20g for a double concentrate. The amount of powder will be adjusted according to the daily state of the coffee beans.
 

Espresso powder to water ratio

The ratio here refers to the ratio of the amount of coffee powder to the amount of coffee liquid, which is generally between 1:1.5-1:2.5. It is more common to use a ratio of 1:2, such as 17g of coffee powder to extract 34g of coffee liquid. The ratio is affected by two factors, one is the amount of powder and the other is the amount of water. If the ratio is too low, the coffee will taste very rich and heavy, and it is easy to have a bitter taste caused by over-extraction. On the contrary, if the ratio is too high, the drink will taste dull and sour due to insufficient extraction. The Nuanyang blended coffee beans used by FrontStreet Coffee use sun-dried Yirgacheffe coffee beans and Honduran sherry barrel coffee beans. Because we want to highlight the whiskey aroma, the ratio of powder to water is generally 1:1.9-1:2.

Extraction time

Time refers to the entire extraction time from buttoning up the handle and pressing the extraction button to the end of extraction. The factors that affect the extraction time are grinding degree and ratio. The ratio is easier to understand. If the ratio is higher, more water is needed for extraction, and the time will naturally be longer. The grinding degree affects the thickness of the coffee powder, and the thickness will directly affect the density of the coffee powder. The finer the coffee powder, the denser the powder cake will be after filling, making it difficult for water to pass through, and the time will be lengthened and easily lead to over-extraction.
 

The freshness of the coffee beans will also affect the extraction time. Too fresh coffee beans will accumulate too much carbon dioxide. Under high-pressure extraction, the coffee oil and carbon dioxide will produce an emulsification reaction, so the extraction time will also become longer and rich yellow foam will be released. If the coffee beans are not fresh, the water absorption of the beans themselves will be weakened, so the speed of water passing through will be accelerated, the extraction time will be shortened, and the espresso coffee that comes out usually does not have too much oil.

flow rate

The flow rate is the speed at which the coffee liquid flows down. The final goal of our extraction parameters is actually a result of the flow rate. Our espresso coffee needs to start dripping the first drop of coffee liquid five seconds after pressing the extraction button, and then the extracted coffee will flow out evenly. In half of the cases, Front Street uses 18-20g of powder to extract 35-40ml of coffee liquid, and half of the extraction time is between 27-30 seconds. The speed of the flow rate will directly reflect whether the grinding degree and proportion are appropriate.
 

pressure

The average extraction pressure of a coffee machine is about 9 bar, which is determined by the performance of the coffee machine. If the pressure is insufficient, the extraction efficiency will be low, and if the pressure is too high, it will be easy to over-extract. So when buying a coffee machine, remember to compare the parameters. The more expensive the better, right?

water temperature

When the coffee flow rate is too fast/too slow, how should we adjust it?

The flow rate of espresso depends on several factors, the grind level, filling pressure, and the condition of the coffee beans. Grinding thickness is one of the key factors that affects the flow rate. The coarser the grinding degree, the faster the flow rate, and vice versa. The fast flow rate may also be caused by insufficient filling pressure.  The state of the coffee beans is also a factor that affects the flow rate of espresso, including the degree of roasting of the coffee beans and the freshness of the coffee beans (exhaust state).
 

Therefore, when the espresso flow rate is too fast/too slow, you may wish to check it one by one and adjust the extraction parameters as soon as possible. First, check the status of the coffee beans, because it is easier to check. Secondly, check whether the extraction parameters are accurate, whether the powder volume, liquid volume and filling pressure are accurate. You can first adjust the powder to water ratio and adjust the flow rate by increasing/decreasing the powder/powder amount to obtain the fastest adjustment efficiency. When all factors are eliminated, adjust the grinding degree.

How to calculate the concentration of espresso and the appropriate extraction rate range?

Strength represents the proportion of "extracted coffee substances" to the total coffee liquid in a cup of coffee. Strong coffee strength ranges from 8% to 12%. Extraction rate represents the proportion of "extracted coffee substances" to the total coffee bean weight. The extraction rate is between 18% and 22%.
 

| How to measure espresso strength?

First, calibrate the concentration tester and clear the standard with pure water. Then stir the extracted espresso, use a titration test tube to extract the coffee liquid in the center, put it into the coffee concentration tester, press the measurement button, and try to measure the value multiple times until the value is stable.

| How to calculate espresso extraction rate?

Extraction rate = concentration + weight of coffee liquid) = weight of coffee beans.
 

Front Street uses a blend of sun-dried Yirgacheffe and Honduran sherry coffee beans, and uses 19g of powder to extract 40ml of coffee liquid in 28 seconds. The coffee concentration measured using a coffee concentration meter was 8.97%. Then the extraction rate is (8.97 divided by 37) = 18 ~ 18.44%, so the concentration of the espresso extracted by Front Street this time is 8.97%, and the espresso with an extraction rate of 18.44% belongs to the espresso range of the Golden Cup.

Does coffee within the Jinbei range necessarily taste good?

Of course, not all Jinbei coffee is necessarily a cup of delicious coffee. Coffee is a very personal and subjective drink. The right thing to do is to keep trying and find the coffee you like. The Golden Cup is just a reference system for us to adjust our coffee.