What Are the Differences in Brewing Techniques for Dark and Light Roast Coffee? Unlock the Secrets to Perfect Coffee Brewing!

Friends often ask FrontStreet Coffee for the best brewing parameters after purchasing beans from our physical store, aiming to reduce the chances of brewing failures and directly create delicious coffee. FrontStreet Coffee then introduces the characteristics of the beans to customers and shares the optimal brewing parameters.

For example: because this bean is lightly roasted, the water temperature should be relatively high, around 90°C~93°C, and the grind should be relatively fine; or, this bean uses dark roast, so the water temperature should be relatively low, around 86°C~89°C, and the grind should be relatively coarse. Time and coffee-to-water ratio are the same for both, controlled at about 2 minutes and 1:15.

So yesterday, a friend felt confused: "Why do light roast beans require higher water temperature and finer grind, while dark roast beans need lower water temperature and coarser grind?"

How are the brewing frameworks for dark and light roast coffees established?

As FrontStreet Coffee mentioned, this is the result derived from their characteristics! If you want to brew a cup of delicious coffee, then we need to find the optimal brewing formula that suits the current coffee beans. Time, ratio, grind, and water temperature are the four important parameters that construct this formula. Among these four parameters, we mainly adjust the water temperature and grind. (Because the coffee-to-water ratio primarily determines the concentration of the coffee and generally has a fixed range. Time, being uncontrollable directly, is fixed as a benchmark to measure whether other parameters are appropriate, so these two are not the main adjustment targets.)

The characteristics of light roast coffee beans are high density and difficult extraction. Because the bean's roasting time is relatively short, the coffee beans haven't expanded excessively, maintaining a relatively high density. Dark roast beans are exactly the opposite! Because the roasting time is relatively long, the expansion coefficient of the coffee beans is larger, so the density isn't as high.

The level of density determines the ease of extraction! Compared to dark roast coffee beans, light roast beans are more difficult to extract because the ground coffee powder density is higher, making it harder for hot water to penetrate! At the same time, high density also leads to a more compact powder bed structure, which is not conducive to full contact between coffee powder and water. Therefore, FrontStreet Coffee uses a relatively higher water temperature when brewing light roast coffee beans to improve extraction efficiency, allowing the coffee to be fully extracted.

Dark roast beans are the opposite - because of their higher expansion rate, lighter weight, and faster water absorption speed, the flavor substances in the coffee are more easily dissolved. Therefore, FrontStreet Coffee uses a relatively lower temperature when brewing dark roast beans to reduce extraction efficiency and avoid the risk of over-extraction.

Impact of Roast Level on Grinding Characteristics

Furthermore, the roast level of coffee beans also affects their toughness! When coffee beans are lightly roasted, their toughness is higher and brittleness is lower; when coffee beans are darkly roasted, their toughness is lower and brittleness is higher. The toughness/brittleness of coffee beans determines the quality of coffee powder during grinding. With the same grind setting, beans with higher brittleness will produce more fine powder and a larger surface area! Beans with lower brittleness and higher toughness will produce relatively more uniform particles with less fine powder and a relatively smaller surface area.

This is easy to understand, just like breaking cookies! Extremely brittle cookies only need a gentle break to shatter, while also producing many tiny crumbs! If we break cookies that aren't as brittle, the crumbs produced when breaking the cookie will be much less. The same principle applies to grinding coffee beans. In other words, with the same grind setting, the total surface area of particles from dark roast beans will be larger than that from light roast beans, with a higher screening rate. This is why dark and light roast beans require different grind sizes! Because dark roast beans need to use a relatively coarser grind to reduce surface area and fine powder, avoiding over-extraction during brewing due to high extraction efficiency or blockage caused by fine powder; while light roast beans need to use a finer grind to increase surface area and enhance extraction efficiency (all relative).

Brewing Tools and Techniques

The above are the reasons why adjustments in grind and water temperature are needed when brewing dark and light roast beans. Besides parameters, FrontStreet Coffee also uses different tools and techniques during brewing! Let's first discuss tools. Because the coarseness of the grind and the density of the coffee powder together affect the water flow rate, FrontStreet Coffee also uses different flow rate drippers to assist in controlling the coffee extraction time. When brewing light roast coffee, because the coffee powder density is high and the grind is fine, this increases the resistance of the powder bed, leading to slow water flow. Therefore, FrontStreet Coffee pairs it with a fast-flow V60 dripper to increase water flow speed, avoiding over-extraction due to too slow flow rate; while when brewing dark roast beans, because the coffee powder density is low and the grind is coarse, a slower-flow Kono dripper is needed to slow down the water flow speed, ensuring the coffee can obtain sufficient extraction.

Water Pouring Techniques

Next is water pouring! Because most light roast coffee powders are quite heavy, the powder bed is difficult to be lifted by water flow. Therefore, FrontStreet Coffee usually uses a small water flow when extracting this type of coffee, avoiding too large a water flow that would flood the powder bed, resulting in too low concentration and weak coffee flavor. This article is a good example "How to Brew Light Roast Coffee?", but it's only suitable for very high-density beans; other beans can be brewed using the conventional three-stage method~

Then when brewing dark roast coffee beans, because the coffee powder is lighter in weight, the powder bed can be easily lifted to form a powder wall. Therefore, FrontStreet Coffee usually uses a large water flow to pour water, building up the powder bed, then focusing on extracting the coffee powder at the bottom, making the extraction more uniform!

- END -

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473