Coffee brewing is no rocket science. Knowing all 4 important variables in coffee brewing in relation to roast level allows you to brew the best cuppa every single time. Let's get started!
Roast Level & Brew Ratio ⚖️
There is a correlation between brew ratio & roast level of coffee beans. It’s best to take into consideration on brew ratio when you switch coffee beans at the different roast levels.
The general rule, the more water (in ratio) you use, you’ll get to extract more of the ground coffee, ie result in higher extraction.
The darker the roast level, the higher the solubility of coffee beans. Hence you don’t need much water in ratio to extract a very soluble dark roast coffee.
Light roast not as soluble as dark roast coffee.
On the other hand, you’ll need more water in ratio to extract light roast coffee as it’s not as soluble. Using more water will result in sweeter light roast coffee 😋
Here are the brew ratio recommendations for different roast levels of coffee beans,
Light roast - 6g per 100ml
Medium roast - 6.5g per 100ml
Medium-dark roast - 7g per 100ml
Dark roast - 8g per 100ml
Grind finer for lighter single origin espresso roast coffee.
The same goes for espresso! For darker roast coffee beans, use a brew ratio of 1: 1.3 or below for a more intense, full bodied ristretto that goes incredibly well with milk!
Especially if you are making latte or cappuccino with espresso blends! A good recipe is 18g brew to 28g or below to punch through the milk for a velvety latte 💪🏼
For lighter single-origin espresso roast coffee, a ratio of 1:2 above is good to fully extract a sweeter & flavourful espresso. Best as espresso or long black!
The usually recipe we use for single origin espresso is 18g brew to 36g espresso. You’ll get a juicy jammy espresso with sweet finish
The Extraction - Grind Size 🧐
There are two things to consider when it comes to grind size.
First is the type of brewing equipment. Different brewers require different grind sizes.
The brewing time using espresso machine is less than 40 seconds, hence it needs a fine grind size to slow down the espresso flow rate of & larger surface area to encourage extraction.
Whereas drip pour over methods needs a medium grind size so that the flow rate is not too slow & brew time doesn’t drag too long.
For French Press & cupping, coarse ground coffee is best to avoid over extraction.
If you brew with different brewers at home, the best is to have a list of grind settings for different brewers. There you’ll get a rough idea of which grind size to start with! 😉
Coarse grind size for French Press
The second, is the roast level of beans.
The darker the roast level of coffee, the more soluble the coffee beans. Hence you’ll need to make minor adjustments depending on the roast level 🤏🏼
The very soluble Dark roast coffee is best with a coarser grind size to prevent over-extraction, whereas light roast(that’s not as soluble) is best to go finer to open up more surface area & encourage extraction 🤗
Let’s say if you have been brewing dark roast coffees and decided to switch to medium or light roast coffee, you MUST change the grind size to a FINER setting! (Ps: before that, please clean your grinder before that 😉)
Different roast level of beans needs different grind setting
But how fine to grind? The only way to find out is by tasting it and evaluating the aftertaste!
If the coffee tastes very sour & watery on the aftertaste, it’s under-extracted and needs a FINER grind size (& higher brewing temperature) to encourage extraction!
If the coffee tastes very BITTER astringent aftertaste and gives a dry throat sensation after swallowing, it’s over-extracted and a COARSER grind size will make the coffee sweeter 😋
A well-extracted coffee tastes super sweet with great aromatics and leaves a lovely soothing aftertaste that lingers on your palate.
If your cup of coffee tastes extreme either sour or bitter, the first thing to adjust is the grind size only!
We highly recommend keeping the brew ratio extract the same when you adjust grind size, adjust one thing at a time ☝️
The Extraction - Brewing Temperature 🌡
If you like to brew a variety of coffees with different roast levels (like us!), this is SUPER IMPORTANT for you!
As mentioned earlier, darker roast coffees are more soluble & much easier to extract than lighter roast coffee. The darker the roast, the more soluble the bean is.
Hence different roast level of coffee requires different brewing temperature to achieve the optimal extraction for the sweetest and most flavourful cuppa!
Getting the water temperature wrong will often result in either being too bitter (over-extraction) or too sour (under extraction) 🙃
Here’s our recommended brewing temperature,
Light roast coffee, try 95-98ºC
Medium roast, try 93-95ºC
Medium-dark roast, try 90-93ºC
Dark roast, try 85-90ºC
As light roast coffee is not as soluble, it requires a greater amount of energy (heat) to extract all the flavours & sweetness in light roast coffee.
Hence a lower brewing temperature for light roast coffee often results in unpleasant sourness, watery and hollowness from under-extraction, even brewing with a finer grind size 😧
The opposite for very soluble dark roast coffee, high brewing temperature easily results in over-extraction that super bitter and harsh aftertaste 🤮
With a low brewing temperature, you’ll get a smooth bittersweet cuppa with a long everlasting aftertaste.
If you are brewing with French Press that takes 4 minutes of brew time, use the upper range of brewing temperature to ensure sufficient heat to extract the coffee!
The Extraction Finale - Brew Time ⏱
Now that you know about the relation of roast level with brew ratio, grind size & brewing temperature, now you need to know about the last one, brew time!
The reason that brew time is the last mention is that brew time co-relate to the brew ratio & grind size.
Also, there is no fixed time for most brewing methods, except for French Press & cupping.
If you are brewing light roast coffee on V60 using 15g finer ground coffee to 250g of water, it will take over 2-3 minutes to complete the brew.
For dark roast with 16g brew to 200ml water with coarser grind size, total brew time will be below 2 minutes as water flows faster on coarse grind size & less water is used.
If you are brewing 5 cups with 60g with 1 litre of water, it will take 4-5 minutes to complete as it takes a longer time to slowly pour all 1 litre of water.
Small cup coffee, shorter brew time
The same goes for espresso, dark roast with a smaller ratio (1:1) and coarser grind size will complete much faster than light roast with a higher ratio of 1:2 above & a finer grind size.
A good range of espresso brew time is about 20 seconds for dark roast and 30-40 seconds above for lighter roast.
The same applies to pretty much all brewers, Moka pot, Chemex, Aeropress and all drip diffusion brews. The finer the grind size, the longer the brew time will take.
Hence brew time is not as important for most brewers, but it gives you a rough idea of how the extraction will be 😲
If your dark roast coffee brews longer than expected, you can get some sugar ready for a super bitter cup 🤮
4 minutes flat for French Press
There are 2 exceptions, the French Press & cupping that takes total of 4 minutes! 4️⃣
French Press & cupping is immersion brewing and it’s not as ‘efficient’ in terms of extraction as compared to diffusion brewing. Hence it takes a longer time of 4 minutes brew time to complete the extraction!
The best way to stop brewing in French Press is by using a spoon to break the crust like cupping! This stops the coffee brewing process and all the ground coffee will sink bottom.
The Extraction Fix - By-Pass Dilution 💧
After knowing about coffee extraction, here’s a bonus to fix any brewing mistakes ☝️
Bypass is adding hot water into the brew to dilute the intensity of the coffee. It’s a quick & easy fix for any brewing mistakes.
We all make mistakes all the time. Sometimes we brew with too much ground coffee, grind size too fine, water too hot etc.
As a result, coffee is over-extracted & tastes super intense & bitter 🥴 To fix that, just add some hot water into the coffee to dilute the brew will do!
Add little water into coffee to 'loosen' the intensity & bitterness
Bypass is great when brewing with ‘older’ coffee beans that are over 1 month after roasting 😲
As roasted coffee beans age, the gas in coffee beans will be significantly reduced together with the aromatics. Hence there will be ‘lesser’ flavours to extract old beans.
For that, you can brew with a higher dosage of beans & lesser water of 80g per litre & a slightly finer grind size for a higher surface area to cut down the brewing time.
Once done brewing, just add some hot water to dilute the brew to balance & make it easier to drink!
Lastly, bypass is only useful if coffee is over extracted or too intense. If coffee is under extracted watery, adding more water will only further dilute the coffee..
Hope this help to elevate the deliciousness of your daily cuppa. Happy brewing!