Jori Korhonen //
// 31.8.2017

How to Brew the Best Filter Coffee - Advanced Tips

Let’s get really geeky for a moment and talk about coffee brewing recipes. I’ll will be talking about filter coffee brewing recipes this time, but same things concern espresso to some extent.

Coffee brew ratio – stronger or milder coffee?

Definition of ratio is “the relationship between two groups or amount that expresses how much bigger one is than the other” (definition of ratio in Cambridge Dictionary). So, in our context, how much coffee should you use in relation to water. The norm is that you should use 60 grams of coffee to 1000 grams of water (1:16,5). With that ratio, you can’t basically go wrong and you will have medium bodied balanced cup where you can taste the distinctive characteristics of the coffee. 

What happens if you use a different ratio? Let’s take 1:15 ratio. So now you’re using the same amount of coffee, 60 grams, but due to the ratio our amount of water changes to 900 grams. So you’re using less water to the same amount of coffee which results in stronger and more bodied coffee. On the other hand, if you use 1:18 ratio (60g/1080g), you will have milder but more distinctive taste and less body. When creating a recipe to a specific coffee, you just need to test these ratios with same grind setting to find the perfect ratio. Try out the same at home! If you feel like your last cup was too strong and you didn’t get many tastes out of it but the brew time was adequate, make your next cup with a lighter ratio.

You should always use a scale when testing different brew ratios. If you don’t, you might easily have a bad brew ratio. 

Brew time determines grind size

As the stated above, coffee brewing time determines grind size. In an ideal situation, brew time tells you how fine or coarse grind you should use. If you need to use short brew time (e.g. espresso), then your grind size should be really fine so that the water catches all the good flavors from the coffee and the coffee doesn’t taste too weak. On the other hand, if your method/device requires long brew time (e.g. French press), you should go coarser so that you don’t over extract your coffee. Perfect example from this is Chemex, which has a really thick paper filter but the brew time should be quite close to other pour over methods. This is why you should grind closer to 600 μm when brewing with Chemex. Otherwise, your brew will over extract. Below I have listed suitable particle sizes for some brewing methods:

Device Grind size μm Brew time
Pot coffee 800-1000 5-10 min
French press 700-800 4-5- min
Coffee brewer 500-700 4-6 min
Pour over 400-600 2-4 min
Espresso 100-300 20-30 sec
Turkish coffee 50-150 short boil

Bigger yields also require coarser grinding. If you want to brew two cups, set the grinder just a little coarser than with one cup so that your brew time doesn’t become too long. This rule only apply to pour over methods since the water runs through the coffee bed. Don’t make the water to have too long (or short) journey!

Coffee brewing temperature: tweak your brew to perfection

Take your water seriously. You can start by reading thorough article about coffee and water (written by Karkki, our water specialist). In this blog post I concentrate only on the temperature of the water. 

Water temperature is quite often forgotten, though it is crucially important when brewing good coffee. If you are brewing your coffee with too high temperature, you will have a risk of over extracting it leaving your coffee tasting bitter. On the other hand, too cold water might make your coffee tasting weak and sour. We don’t want either of these situations.

Educational studies have shown that suitable water temperature for brewing coffee is 90,5-96 Cº. Brewing with lower temperature will extract less soluble parts from the coffee and with different distribution of flavors than with hotter water. Generally speaking, darker roasts prefer lower temperatures because they might turn out to have too much bitterness in the cup brewed with high temperature. Lighter roasts on the other hand require higher end temperatures due to their higher density when they require a little more power from the water to give up the good stuff.

Water temperature brewed coffee

You should pay attention to water, but it shouldn’t be the first thing in your mind. I wouldn’t advice changing the water temperature until all the other factors (brew ratio, brew time, grind size etc.) are perfect and you are looking to enhance some specific flavor. Higher temperature tend to brew sweeter coffee and lower temperature more bright and acidic flavors.

Dripping technique is a key to even extraction

Dripping technique

Dripping is an important aspect when brewing pour over coffee. You easily ruin your otherwise perfect cup with bad dripping. And what is bad dripping? Check your coffee brewer next time you brew your black liquid gold. Is the coffee bed an even after the brewing, or does it have a big crater in the middle of the coffee bed? The crater is a perfect example of bad dripping. Even coffee bed means even extraction, which equals good coffee. When brewing manually, try to distribute the water as evenly as possible. I always use spiral movements: I start from the middle and end up pouring to edges of the vessel. It helps if your kettle has a gooseneck that makes the pouring easy and controllable. 

Even extraction brewed coffee

Dripping technique has effect on brew time and temperature. More water in the filter means that the water has more weight forcing it through the coffee bed, which will result in shorter brew times. Likewise, more water in the filter will mean higher water temperature overall since the brewing device doesn’t draw all the heat from the water. In a nutshell, if you want more acidity in your cup, drip slower and on the other hand, if you wish a sweeter cup, drip a bit more aggressively.

Make your coffee bloom!

Blooming, as the word itself kind of states, is in my opinion the most beautiful sight in coffee brewing. The blooming occurs when you pour hot water on fresh ground coffee. The water makes the ground coffee to release carbon dioxide that carbonates the coffee bed. Just in case if you’re wondering, those bubbles during blooming or coffee brewing are the same as in Coke or Fanta. The carbonation will make the coffee bed expand and might double the size of the bed. Blooming is considered as an important part of brewing good coffee. 

Blooming coffee

I usually bloom my filter brews with 50-100 grams of water. Good rule of thumb is to use three times water compared to your amount of coffee. For example, if you’re using 20 grams of coffee, then you bloom with 60 grams of water. Blooming time depends on what kind of coffee you’re using. Freshly roasted coffees require longer blooms (30-45 seconds) and older roasts shorter (15-30 seconds). Blooming time is also dependent on roast level, as lighter roasts like longer blooms and darker roasts shorter so that they won’t over extract. 

Why is it important? Think of blooming kind of the same thing as warm up before sports. To be able to give your best, you have to warm up your muscles so that they reach their full potential. Blooming enables the coffee to reach its full potential by helping creating even coffee bed thus even extraction. The carbon dioxide is a block for the water that might keep the water from extracting all the wonderful soluble solids inside the coffee.

This all may seem overwhelming, but don’t worry. You don’t always have to be perfect. The not-so-perfect cups will also taste good enough and being nerdy isn’t always necessary. These are tips how you are able to influence your cups’ taste and make perfect coffee repeatedly.