Should Fine Powder in Coffee Be Sifted Out? How Should Fine Powder Sifted from Coffee Grounds Be Handled?

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Coffee grinding has a significant impact on the flavor of a cup of coffee. Even the best grinders can produce fine powders, and ordinary household hand or electric grinders may be somewhat unsatisfactory in grinding. FrontStreet Coffee would like to share a brewing solution for excessive fine powders.

How are fine powders produced?

Most grinders use two cutting discs that rotate to cut coffee beans. For example, ghost-toothed disc grinders use two ghost-toothed shaped discs rotating at high speed for grinding. Although the characteristic of ghost teeth is to cut coffee beans into countless small round particles, making the particles more uniform, this feature creates a squeezing effect between the two discs, which can "press" the coffee beans until they break, bursting out some tiny powders.

Generally, coffee particles smaller than 250 micrometers are called fine powders. Therefore, one standard for judging whether a grinder is excellent is whether its fine powder rate is low.

What impact do fine powders have on pour-over coffee?

Excessive fine powders can block the drainage holes of the filter cup, causing slow flow rate and the risk of over-extraction. Moreover, the particle size of fine powders is much smaller than other coffee particles, making their extraction efficiency higher than normal coffee particles, causing local over-extraction (of the fine powders) and resulting in undesirable flavors.

So wouldn't it be fine to just remove all the fine powders? This method is indeed feasible, and the brewed coffee is indeed much cleaner, but you'll find it's too clean to the point of being somewhat hollow, similar to the feeling of insufficient flavor.

FrontStreet Coffee also reached this conclusion through a comparative experiment, comparing normal brewing with brewing after sieving out fine powders.

FrontStreet Coffee Kenya Assalia AA

Country: Kenya
Region: Thika, Kenya
Processing Station: Asali Honey Processing Station
Altitude: 1550-1750 meters
Grade: AA TOP
Varieties: SL-28, SL-34
Processing Method: 72-hour washed
Roast Level: Light roast

Brewing Parameters

Coffee amount: 16g (if sieving, ensure 16g after sieving)
Coffee-to-water ratio: 1:15
Water temperature: 91°C
Grind size: Normal pour-over grind (80% pass-through rate with #20 sieve)

This time, we used segmented brewing. First, inject 30g of water for a 30-second pre-infusion, during which the coffee expanded quite fully. For the second segment, inject 120g of water in small circles at the center. The pouring height was 5cm, with gentle force, without intentional stirring. Wait until the water level drops to 1/2 of the coffee bed before starting the third segment of pouring. In this segment, pour gently from the center outward in circles, with a water flow rate of approximately 4g/s, until reaching 240g to end the pouring. Wait until all the coffee liquid in the filter cup has dripped through to finish extraction, with a time of about 1 minute 50 seconds.

Flavor Comparison Results

Normal: Has flavors of cherry tomatoes, grapefruit peel, cocoa, and black tea, but the overall profile is quite light, and off-flavors appear as the temperature drops.

Sieved: Bright, clean, and transparent fruit acidity, cherry tomatoes, hollow.

Regarding whether fine powders should be sieved out, FrontStreet Coffee believes that appropriate fine powders can fill out the richness of flavor, but fine powders are prone to over-extraction, causing off-flavors. To address this, FrontStreet Coffee recommends a method to deal with this problem.

Brewing Parameters

Coffee amount: 16g
Coffee-to-water ratio: 1:15
Water temperature: 91°C
Grind size: Normal pour-over grind (80% pass-through rate with #20 sieve)
Fine powder rate: 12.5% (<250μm) / 2g fine powder
Filter cup: V60

1. Use a 250-micrometer sieve to separate the fine powders, pour in the coffee powder after sieving out the fine powders, and inject 2 times the water amount (28g) for a 30-second pre-infusion.

2. After the pre-infusion, proceed with the second segment of pouring, injecting 120g of water in circles from the center outward.

3. Immediately after the second segment of pouring, pour in the 2g of fine powders just sieved out, then use a water column to wash down the fine powders until reaching 240g. After the coffee from the filter cup flows into the serving pot, remove the filter cup to finish extraction. The total extraction time is 2 minutes.

This brewing method can retain the flavor of fine powders without over-extraction, making the coffee's flavor more abundant. If your grinder produces a lot of fine powders, you can use this method for brewing.

For grinders that produce more fine powders, adding fine powders later might be a good choice. After all, fine powders are easily extracted quickly in a short time, and they may already be over-extracted before the other coffee powders in the filter cup are fully extracted.

However, if you brew after sieving out the fine powders, you're likely to get a coffee with weak flavor layers or even a bland taste. So you can try pouring in the fine powders before the second segment of pouring!

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Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473