Pour-Over Coffee Grind Size Standards How to Determine Grind Size for Single-Origin Coffee Beans

Beginners in pour-over coffee often visit FrontStreet Coffee asking how to determine the grind size for each coffee bean, how grind size affects coffee extraction, and how to distinguish the fineness of coffee grounds at home. In this article, FrontStreet Coffee will discuss grind size for pour-over coffee.

The Impact of Grind Size on Coffee

Grinding is crucial for coffee. The size of coffee particles directly affects the efficiency of water extraction from the coffee. Theoretically, the more uniform the coffee particle size, the more consistent the overall extraction efficiency, resulting in better coffee flavor. Concentration and extraction rate decrease as the grind becomes coarser and increase as the grind becomes finer. Grind size refers to the size and shape of coffee after grinding, which also determines the surface area. The finer the coffee grounds, the larger the surface area, increasing the contact area between water flow and coffee, allowing more substances to be extracted. Increased surface area (coarser grind) also provides more places for carbon dioxide inside the coffee beans to be released.

Roasting's Effect on Coffee Bean Aroma and Carbon Dioxide Production

Roasting brings out the full aroma of coffee. The Maillard reaction refers to the series of degradation and polymerization reactions between monosaccharide carbohydrates and amino acids. This reaction occurs throughout the entire roasting process. Monosaccharides and amino acids react at different temperatures to produce many complex aromas. Nut, almond, cream, and chocolate aromas come from the Maillard reaction. Caramelization is the oxidation and browning reaction of sugars during heating, producing honey, maple, caramel, and other aromas. Simply put, the longer the roasting time, the more acidic substances in the coffee beans are released. For medium roasts, lighter-roasted coffees have more pronounced acidity with citrus and berry flavors. Darker roasts have more prominent caramelized flavors like cocoa, caramel, and nuts.

In addition to creating aroma in coffee beans, roasting also produces carbon dioxide inside the beans. The darker the roast, the more carbon dioxide is produced. Therefore, to ensure better carbon dioxide release during brewing, FrontStreet Coffee recommends resting coffee beans when purchasing freshly roasted ones. Resting allows coffee beans to release carbon dioxide naturally through the degassing valve on the packaging without opening it, helping aromatic substances and oils integrate and bringing all aromatic substances inside the beans to an easily extractable state. FrontStreet Coffee recommends resting light to medium roasted beans for 3-4 days from the roast date, and medium to dark roasted beans for 5-6 days from the roast date.

How to Determine Coffee Bean Grind Size?

Using FrontStreet Coffee's freshly roasted coffee beans as an example, pour-over single-origin coffee beans are divided into light to medium roast and medium to dark roast.

FrontStreet Coffee's light to medium roasted coffee beans: Light to medium roasted beans will exhibit acidity, while caramelized substances are not easily extracted. FrontStreet Coffee recommends using medium-fine grind size (80% pass-through rate on a #20 sieve with 0.85mm mesh, equivalent to fine sugar size). Medium-fine grind size can slow down water flow through the coffee bed, better extracting acidic substances, sweet substances, and caramelized substances to achieve balanced coffee flavor. Medium-fine ground coffee is recommended to be brewed at 90-91°C. Too high a temperature will over-extract caramelized substances, producing bitterness; too low a temperature will under-extract, only extracting some acidic and sweet substances, making the coffee taste bland and uninteresting.

FrontStreet Coffee's medium to dark roasted coffee beans: Medium to dark roasted beans generally have low acidity with prominent body, meaning caramelized substances are more abundant. FrontStreet Coffee recommends using medium-coarse grind size (70% pass-through rate on a #20 sieve with 0.85mm mesh, equivalent to coarse sugar size). Medium-coarse grind can speed up water flow through the coffee bed, preventing caramelized substances from being over-extracted, allowing the coffee's flavor and mouthfeel to be sweet and full-bodied without producing unpleasant bitterness. Medium-coarse ground coffee is recommended to be brewed at 86-88°C. Too high a temperature will make the coffee bitter and difficult to drink; too low a temperature will make the coffee taste bland and uninteresting.

How to Use a 0.85mm #20 Sieve?

Regarding grind size, FrontStreet Coffee determines it through sieving, based on the Speciality Coffee Association (SCA) recommendations for pour-over coffee, combined with practical operation verification. If you don't have a sieve at home, FrontStreet Coffee suggests observing water flow speed to judge - if water flows too fast, the grind is too coarse; if water flows too slow, the grind is too fine.

First, prepare 10g of coffee beans for grinding, initially set a grind size based on fine sugar and coarse sugar sizes, then pour into the sieve, cover with the lid, and shake left and right until no more coffee powder passes through the sieve. Then prepare an electronic scale and container, tare to zero, pour the sieved coffee powder into the container and weigh. If the sieved coffee powder reaches 80%, it's medium-fine grind; if it reaches 70%, it's medium-coarse grind. If the pass-through rate is too high, adjust the grind coarser; if the pass-through rate is too low, adjust the grind finer.

The Importance of Grind Uniformity

Ground particles should be uniform. After coffee beans are ground, they become powder. The distribution of particle sizes has a significant relationship with the quality of the coffee beverage. The more concentrated the particle sizes within the target range, the more uniform the grind and the better the flavor. If there are too many coarse particles, the deep flavors hidden inside the coffee cannot be extracted; if there are too many fine particles, the coffee will taste too complex and bitter. If serious uneven grinding occurs, FrontStreet Coffee recommends changing the grinding equipment.

For professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat official account: cafe_style).

For more specialty coffee beans, please add FrontStreet Coffee's private WeChat: kaixinguoguo0925

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473