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How does coffee roasting affect your brew recipe?

Have you ever followed a roaster's recommended brew recipe and got underwhelming results? Or worse still, they didn't even provide a recipe? There are many factors that affect how you should approach calibrating a coffee. One of the major factors is how the coffee was roasted. Here's how coffee roasting affects your brew recipe.
How do you normally approach brewing a coffee for the first time? Do you just plug and play your favourite recipe and expect the coffee to turn out amazing? You should look at the color of the coffee, determine how light or dark it is and adjust your grind size and brew ratio according to the color, right? 


Visually inspecting a coffee or even using an agtron meter to measure the color of the coffee tells you nothing more than the amount of caramelisation of the roasted coffee. It doesn't tell you anything about the eveness of the roast, the acidity, the roast speed and the solubility of the coffee. That's just the beginning, but I am getting ahead of myself here.

You cannot replicate a roaster's brew.

First off, 99.99% of the time, you're not using the same water as the roaster. Nor the same grinder, nor brewer, nor the same recipe. Wait what? Not the same recipe? Yes, not even the same recipe. Coffees change. they age, degas and a recipe that worked yesterday might be inadequate today and barista or roasters might recalibrate the coffee using a different recipe.

So then how should you approach brewing the coffee for optimal intended results? Or if you ARE the roaster, how should you advice your customers to brew the coffee? How can you give them the experience that you want them to have?

How does the roast affect your brew recipe?

There are so many levels to this, it is near impossible to cover within a single blog post. But I will try to summarise it as much as I can. If you want the full version, I go through how every roast variable can affect a barista's brew recipe in our Ultimate Coffee Roasting Course.

When you roast a coffee, its solubility is affected by your roast parameters. In this instance, solubility specifically refers to the speed and ease in which water is able to access and dissolve the different compounds in the coffee.

The first clue that many people look for is the color of the coffee. A lighter roast tends to be less soluble as opposed to a dark roast. This is due to the volume expansion that happens whenever you roast a coffee. A darker roast will always puff up and expand more than a light roast.

This expansion means that the coffee bean is more porous and the cell structure has been significantly broken down more than a lighter roast
. The resulting idea is therefore that lighter roasts might require finer grinds to access more of the coffee compared to a darker roast.

However, when mulling over solubility, there is also the impact of roast speed. How fast or how slow you roast your coffee also affects the porousness of the coffee and how brittle it is. The problem is, most roasters almost never include roast time information along with the coffee. The roast time in itself is not even a good metric since it will differ from roasting machine to roasting machine, different batch sizes etc.

In addition to that, there is also the evenness of roast. What happens if the bean is burnt on the outside and raw on the inside? That would complicate things even further.

To top things off, other influencing variables like the water, the grinder and brewer likely differs from the roaster's lab. So how are you supposed to deal with all this complexity? The answer, in my opinion, is to understand how to calibrate coffees and develop your own brew recipe.

Develop your own brew recipe.

Every brewer and recipe highlights different characteristics. From acidity to body, flavour, balance etc. But as I mentioned before, these change as the coffee ages and as roasting inconsistencies creep in from batch to batch.

So here is my solution: Learn to calibrate. Develop your own recipe.

How to calibrate filter coffee?

There are two styles of brewing that I will summarize here.

a) Sweet, round/heavier body, stronger flavours.

General parameters: Medium to fine grind size.
Lower dose (~11g for 1-cup brewer).
Higher brew ratios: (1g of coffee to 16-19g of brew water)

Notes: This style of brewing tends to reveal every aspect of the coffee. Both good and bad. Good flavours will taste great here while flaws in the coffee will also be amplified. Can be very intense for some coffees. Works best with light roasts. Very unsuited for dark roasts as bitterness tends to be amplified here.

b) Light/juicy body, milder flavours, brighter acidity.
General parameters: Coarse to very coarse grind size.
High dose (~15 ;- 20g for 1-cup brewer).
Low brew ratios: (1g of coffee to 10-15g of brew water)
Pour very slowy, split your total brew water into 4 or more separate pours.

Notes: This style of brewing tends to work well with a broad range of coffees. It presents a more acceptable flavour profile across many types of coffees/roasts. It requires less experimentation and tweaking but uses significantly more coffee. It can result in coffees turning sour when cooled for lighter roasted coffees. Darker roasts work best with this style.

How to adjust:

The two methods above highight different characteristics of the coffee. But more importantly, it also has a correlation with the roast degree of the coffee.

If a coffee tastes dark, bitter, smoky, charred or burnt, choose the second style. If a coffee tastes sour, grassy, vegetal, bright or light, choose the first style. If it has both, stick with the second style.

This is regardless of what color the coffee is. Whether it is light, medium or dark roasted, you should go by the taste rather than the visual color of the coffee. From here, you adjust just the grind size to get you to the perfect balance.

The point here is that the finer grind exposes more of the coffee to the water. This means you dissolve more of the coffee and taste it for what it is. So, if it was badly roasted (burnt or low quality coffee), these faults will be amplified. To negate this, we start going from style A to style B.

The trend here is to go coarser and increase your coffee dose. You might also choose to decrease the amount of brew water used. Eventually you will reach a point where all the negative attribtues of the coffee are minimized and you get the ideal cup of coffee. For very dark coffees, you might find yourself adjusting all the way to style B.

Of course you can also calibrate the reverse direction and go from style B to style A. In this scenario we will do the opposite and grind finer but decrease the dose and increase the amount of brew water.

Happy brewing! You can also share your thoughts/recipes and review coffee on our new sister site: We showcase some of our co-roasters and other amazing coffees from Singapore.

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  • Lighter roasts take longer to brew
    By : Yazan Alherbawi On 06/20/2020

    I recently received an extremely light washed Columbian that reads ‘error’ when measuring inner bean on the lighttells color reader (probably due to color being greater than 100 on the scale?).The experience I had with this coffee is that even when using the same grind setting, it produces lots of fines when compared to a darker roast ground on the same setting.I also found that it brews much slower, possibly due to it being less porous? If so, does that call for grinding coarser? The taste notes I got were sort of flat and do not last. With my humble beginners palette, I felt I wanted more inorganic acidity in the cup. Would you recommend a different approach to accentuate more flavor in brewing such a light roast?

    Replied by : Kenneth Ong On 09/01/2020 Hey Yazan, I'd say that ultra light roasts such as this would actually require a much finer grind sizes to properly extract the coffee. It is highly probable that it is indeed less porous and hence you need a finer grind to allow water access to the coffee. I would also suggest using a lower dose with the finer grind.