Should Fine Particles Be Retained in Coffee Extraction?

The Challenge of Excessive Fine Particles in Coffee Grinding

Often, due to issues with grinding equipment, the resulting coffee grounds contain excessive fine particles! At such times, the person preparing to brew faces a difficult choice!

FrontStreet Coffee often says that excessive fine particles become a double-edged sword. While keeping them might yield rich coffee layers, there's a high probability of extracting bitter, over-extracted flavors. If you choose to discard them, although you can reduce uncontrollable over-extraction factors, the resulting coffee might seem somewhat flat! The best solution would obviously be to replace the grinder with a more precise one, but often, many friends, like FrontStreet Coffee, find themselves on a tight budget. So, are there any better solutions?

Why We Need to Sieve Out Fine Particles

Of course there are! Combining FrontStreet Coffee's article on fine particles from last year with various opinions from online coffee enthusiasts, we can derive two practical reference solutions. But before that, we need to sieve out the fine particles first!

Why should we sieve out fine particles? The fact that fine particles themselves are prone to over-extraction is one thing – as long as they're not excessive, they won't significantly impact the brewing process. Moreover, even when using better grinders, some fine particles are always produced, and we typically don't choose to sieve them out because it's unnecessary. However, the key problem lies in that some grinders produce simply TOO! MANY! FINE! PARTICLES! Fine particles are smaller than 0.25mm and can perfectly clog the filter paper's drainage holes, causing liquid that should have filtered quickly to remain in the filter cone for much longer! Amazingly, not only do the fine particles over-extract themselves, but they also drag other particles into over-extraction! Therefore, our first step is to sieve them out – we can discuss solutions after sieving them~

How to Sieve Fine Particles

Simply purchase a fine particle sieve (commonly known as a flour sieve), pour all the ground coffee into the inner pot, cover with the lid, and shake it!!! Shake until you feel the fine particles have been sieved out! For example, when FrontStreet Coffee uses a hand grinder to grind 15g of beans, we sieve out a full 2.5g of fine particles!

This accounts for 16% of the total coffee grounds. If used directly in brewing, it would easily clog the filter paper and extend extraction time! Ultimately, you would also end up with a muddy coffee bed.

Two Practical Solutions for Fine Particles

However, if you remove them, while extraction will be more stable, the inconveniences actually outweigh the benefits: first, you lose 3g of coffee beans and need to replenish them, which requires extra effort – essentially spending both money and energy. Therefore, we can conclude that the best approach is to continue reading! (Yes, this is just padding the word count, isn't it?) Once we've sieved out the fine particles, we can refer to these two solutions! One is to pre-determine the amount to add before brewing to ensure fine particles don't cause excessive negative effects; the other is to add fine particles at the right moment during brewing to reduce the risk of over-extraction.

Solution 1: Pre-determined Addition Method

How much should be added to avoid clogging the filter paper? FrontStreet Coffee specifically conducted experiments on this issue and concluded that when fine particles constitute less than 10% of the total grounds, normal brewing can be maintained with excellent flavor. Once it exceeds 10%, clogging becomes likely! Therefore, what we need to do is keep fine particles below 10%!

For example, if we grind 15g of coffee beans and get 2.5g of fine particles, we can take 1.5g of them for brewing and reduce the originally planned water amount by 15ml! After all, even higher-precision grinders produce similar amounts of fine particles, and as long as other factors remain stable during extraction, the probability of failure will be greatly reduced!

Solution 2: Mid-brew Addition Method (Unconventional Approach)

We place the sieved fine particles aside for later use, and first brew according to the originally set parameters. After pouring the second segment of hot water, we add the reserved 3g of fine particles!

This way, we can appropriately extract the aromatic substances from the fine particles, not only avoiding negative flavors from these 3g of coffee grounds but also preventing the fine particles from settling at the bottom and clogging the filter paper! Other brewing methods can also identify appropriate timing for adding fine particles based on this concept – it's not limited to three-stage pouring. However, this is just a reference approach, and fine particles offer even more possibilities for experimentation. If you have other different ideas, welcome to share them with everyone~

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