October 30, 2023

Post-grind blending: An impractical or novel way to blend coffees?


We’ve seen blends become more popular in specialty coffee over the past couple of years, including at competitions. The 2021 World Barista and Brewers Cup Championships were prime examples, when many of the finalists (and winners) decided to shift away from single origins to use blends instead.

Alongside this recent resurgence, there is often an ongoing conversation in the industry about how roasters can successfully develop a balanced, consistent, and high-quality blend. There are seemingly endless factors to consider, such as origin, variety, roast profile, and the solubility level of each coffee. 

To get the best results, most roasters will roast each blend component separately, and then combine all coffees together – a practice known as post-roast blending. But are there other ways to blend coffees that are just as effective?

In today’s article, coffee professional Elizabeth Sturges explores this practice and questions how practical – or challenging – it could be for coffee shops and home brewers.

You may also like our article on specialty coffee blends: how exciting can they be?

Sampling coffee blends at a roastery.

Changing attitudes about blends

Blends have been a staple of coffee shop menus and roastery offerings for many decades now. For consumers who are looking for more classic flavour profiles, blends are often the most dependable and reliable option.

But at the same time, specialty coffee’s interest in blends has also been rising. And this has created new sensory experiences altogether. While we traditionally think of blends as containing at least two coffees sourced from different countries, specialty coffee has helped to broaden the definition to include:

  • Various regions within a country
  • Coffees from different producers in the same region
  • Different varieties or processing methods from the same farm. In this case, we can refer to these coffees as single-origin blends

Similarly, blends have been historically perceived as being lower in quality than single origin coffees. These negative associations mostly stem from larger commercial roasters who typically blend arabica with lower-quality robusta to keep costs down.

This narrative, however, has changed in recent years – even at high-level competitions like the World Barista Championship and World Brewers Cup. Roasters, coffee shops, and competitors are now becoming much more thoughtful and deliberate when developing or serving blends.

For instance, 2023 World Barista Champion Boram Um used a blend of anaerobically fermented Gesha and natural Pink Bourbon in his milk beverage course. Italian competitor and 2023 WBC runner-up Daniele Ricci also used a blend of Colombian Gesha and Caturra sourced from the same farm.

During their performances, both competitors emphasised how blending their coffees helped to create a more balanced and well rounded taste experience – which even some high-quality single origin coffees may not be able to do on their own.

How do roasters usually blend coffees?

If you ask most specialty coffee roasters about how to best blend coffees, it’s likely they will say post-roast blending. This is when each blend component is roasted separately to achieve the optimal roast profile. Then, all the coffees are mixed together.

And there’s a reason for this practice. While pre-roast blending (when all components are roasted together) can be more efficient, it often leads to uneven roast profile development. This is because different coffees have different bean densities and sizes (as well as hardness levels), which influence how you need to roast them.

Denser coffee, for instance, typically contains more sugars and has a higher moisture content. To ensure proper roast profile development, you should roast these coffees for longer and in smaller batches.

Tamping espresso before brewing.

The relationship between grind size & solubility

Grind size is a key variable when extracting coffee – both as filter and espresso. In simple terms, if your grind size is too fine, your coffee will be overextracted. As a result, there will be more bitter and astringent flavours, with a thinner texture, too.

Conversely, when ground too coarsely, water will flow too quickly through the bed or puck of coffee. This leads to underextraction, with sour flavours and a quick finish on the palate.

Finding the right grind size for every coffee depends on a number of factors. Generally speaking, it boils down to a particular coffee’s sensory profile – and trying to balance acidity, sweetness, bitterness, and mouthfeel as much as possible.

In a coffee shop setting, baristas need to continuously tweak grind size – especially for espresso – to serve balanced and high-quality coffee throughout the day. And this is particularly important when baristas need to add a new coffee to the grinder hopper, as it’s likely they will have to make significant changes to grind size to get the best results.

It can take some time to find the right grind size, even for experienced baristas. But one crucial factor to always take into account is solubility, which relates to how easily coffee can be extracted. Essentially, different kinds of coffee extract at different rates, which depends on a number of factors such as:

  • Origin
  • Variety
  • Processing method
  • Bean density
  • Roast profile

For roasters, this has significant implications on how to create blends, ranging from selecting the coffees to developing roast profiles. All blend components must have similar solubility levels – otherwise the blend will taste both under and overextracted at the same time.

Brewing pour over coffee.

Exploring other ways to blend coffees

Given that grind size and solubility are integral to extracting excellent coffee, are there better ways for roasters to develop blends other than post-roast blending?

One technique could be blending coffees after grinding them. 

Let’s say we have a blend made up of two coffees. On their own, each coffee is likely to need a slightly different grind setting to extract the most balanced and well-rounded flavour profile. 

Suppose the grind setting is X for the first coffee and Y for the second. If roasters blend both coffees prior to grinding, the grind setting can neither be X or Y, as adjusting to either one may result in under or overextraction.

This is where post-grind blending could be a useful practice to create a more harmonious and balanced blend. The dose for each blend component would need to be ground separately, and then combined just before extraction.

Using the above example again, you can use grind setting X for the dose of the first coffee and grind setting Y for the second – before thoroughly mixing both doses together and extracting (whether as espresso or filter).

Is post-grind blending too impractical?

In theory, post-grind blending could help to achieve more balanced and consistent results when using blends. However, there are also many practical challenges that could be very difficult to overcome – especially in coffee shops.

As coffee needs to be ground fresh before it’s extracted, grinding separate blend components is likely to be far too time consuming and complex for most baristas to carry out. Moreover, without formalised training procedures, baristas may struggle to carry out this technique successfully – which could be detrimental to maintaining coffee quality.

Home brewers and coffee professionals could certainly try experimenting with post-grind blending to assess how this method might enhance the sensory experience of blends. Following any results, we could then gauge whether it would be possible to implement this technique successfully in coffee shops.

Creating coffee blends on a coffee farm.

It certainly seems that post-roast blending still remains the most effective and practical way to develop specialty coffee blends. And with blends becoming more and more popular, roasters need to make sure that quality remains a key focus.

While post-grind blending could be a useful practice for home brewers and coffee enthusiasts, those who decide to use this technique still need to be mindful of the potential challenges – or risk reducing coffee quality.

Enjoyed this? Then read our article on how specialty coffee roasters can use blends to drive brand identity.

Perfect Daily Grind

Want to read more articles like this? Sign up for our newsletter!