Coffee grind size is a very frustrating factor. Many of the problems that friends encounter when brewing are caused by inaccurate grinding. For the grinding degree of Pour over(V60) coffee, Front Street recommends using a No. 20 (0.85mm) standard sieve for calibration. The pass rate is 80% (you can use 10g of coffee powder to sift and pass 8g of powder) as the grinding degree of Pour over(V60) coffee.
However, the grinding degree of Italian coffee is very fine, and it is not practical to use a sieve to filter it. So how to determine the grinding degree of Italian coffee?
Italian coffee grinding thickness
If you go to a cafe, please pay close attention. There are at least two grinders in the store, one of which is an Italian grinder that fills the bean bin, and the other is a grinder for hand brewing. Why are there two grinders? In fact, making espresso is very sensitive to the thickness of coffee powder. Changes in thickness that are invisible to the naked eye will be immediately apparent when extracted in a coffee machine.
Therefore, in order to ensure the continuous production stability of espresso, a separate grinder is generally equipped to grind espresso beans. Espresso coffee beans look and feel like flour, and expressed in data, their thickness is between 150-300 microns.
How to determine the grind size for espresso coffee
According to the definition of Espresso (Italian espresso) by the Italian Coffee Association and WBC, a qualified espresso refers to 1 ounce (about 30ml) of espresso with golden oil extracted from hot water at 90.5~96°C under 9 atmospheric pressure within 20~30 seconds.
Although the above statement does not clearly state the specific thickness of the grinding degree. But as long as we clarify the relationship between time and grinding degree, it will be easy to determine the grinding degree.
As long as there are no problems with human factors such as cloth powder and pressed powder, the finer the coffee grinding particles, the longer the extraction time will be, and the taste will be burnt and bitter, which can easily lead to over-extraction. On the contrary, the coarser the grinding particles will be, the extraction time will be short, and the taste will be sour, which will easily lead to under-extraction.
Therefore, when Front Street faces an unfamiliar Italian coffee bean or replaces a new grinder, the idea of determining the grinding degree is: first determine the extraction plan. Front Street’s default Italian extraction plan is 20 grams of coffee powder (depending on the capacity of the powder bowl), using a 1:2 extraction powder-to-liquid ratio, and the time is approximately 20 to 35 seconds.
Then the barista will adjust the grinding thickness according to the roasting degree of the beans. If you like nutty, chocolate, and caramel flavored espresso, buy Front Street Dark Cocoa Basic Blend, Front Street Premium Blend, and Front Street PWN Golden Mandheling. During extraction, Front Street will allow the time to be 20 to 30 seconds, so as to ensure full flavor and avoid over-extraction;
If you are using medium roasted Italian coffee, such as Front Street Strawberry Espresso, Front Street Grana Gesha SOE, Front Street Oiran SOE, etc., Front Street will extract the coffee for a longer time, controlling the time to 25 to 30 seconds, so that the flavor substances can be released more fully.
The roasting degree of the sunflower warm sun blend used by Front Street is slightly lighter than that of ordinary espresso beans, so the ratio of 1:2 is used to highlight the flavor characteristics of sherry coffee and red cherry coffee), that is, 40g of coffee liquid (the weight unit is used because it is more accurate than the volume unit, and the weight of coffee oil is smaller than the volume).
Fixed parameters are used for pressure and water temperature. The pressure of the coffee machine used in Front Street is set at 9bar and the water temperature is 93°C. Then we only need to adjust the grinding degree to achieve the preset time point. Some grinders are equipped with a powder bin, so after each grinding adjustment, the remaining powder needs to be cleaned to avoid affecting the accuracy of the adjustment.
When debugging to within our preset time interval, don’t get too excited. Because what you want is a cup of delicious espresso, you need to taste it to determine whether there are any defective flavors such as bitterness, sourness, wateriness, etc., and secondly, determine whether it has the flavor represented by this coffee. If not, you need to continue adjusting, and at this time the adjustment is not limited to the grinding degree. Because the brewing parameters we preset are based on our cognitive perspective. When facing coffee beans that are unfamiliar to us, we need to consider whether the preset extraction parameters are reasonable.
For example, when Front Street was testing a Front Street Colombian Hija SOE coffee, after adjusting to the appropriate grinding size, the extraction parameters were 20g of coffee powder to extract 40g of coffee liquid, which took 26 seconds. However, when I tasted the flavor, I felt a bit of burnt bitterness. Through segmental testing, I found that the bitterness originated from the tail segment, so I adjusted the extraction ratio to 20g of coffee powder to extract 35g of coffee liquid for 24 seconds.
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
