Multi-variety blends: What roasters need to know

In a market underpinned by single origins and micro lots, blends have become a standout option in specialty coffee in recent years. Often considered “better than the sum of their parts”, they offer layered and tailored flavour experiences that some single origins can’t provide – especially when prepared as espresso.

The most common approach is to blend different origins, including different countries, regions, and farms. Through this technique, roasters can also combine coffees which have been processed in different ways or mix multiple varieties together to create flavours that appeal to a more diverse range of consumers.

Similar to processing method, roasters need to account for each variety’s unique impact on a blend. Bean density and size, solubility level, and flavour profile are key factors that influence the roasting process and overall results. To achieve balance and consistency, roasters need to find the “sweet spot” that accommodates all varieties included in a blend.

Carina Esteves and Ishwor Maharjan, the director of operations and head roaster at Baobá Café, Marc-Alexandre Emond-Boisjoly, the founder of 94 Celcius, and Ashlee Eastwood-Quinn, head of coffee at Rave Coffee, provide their insight.

You may also like our article on whether multi-processed blends dilute or enhance flavour.

Understanding the key differences between varieties

There are thousands of coffee varieties, all of which vary in cup quality and characteristics. For example, Bourbon, one of the most genetically important varieties, is renowned for its sweet and complex flavour profile, while SL28 (a common variety in Africa) typically has distinctive fruity tasting notes.

Pairing and layering complementary flavours in blends is, of course, a priority for any roaster. Whether a blend offers familiarity or a differentiated experience, the flavours of the different components should be balanced and synergetic.

But when creating multi-variety blends, roasters need to consider other factors than flavour profile alone.

“While no two varieties are inherently incompatible, achieving a balanced roast for a blend can be challenging due to differences in bean density and size,” says Marc-Alexandre, the founder of 94 Celcius in Montreal, Canada. “Different varieties, such as Bourbon, Typica, Caturra, or Pacamara, have unique traits related to size, density, sugar content, and chemical composition.

“For example, Pacamara, known for its large size, can be more difficult to roast evenly alongside smaller varieties,” he adds. “Bourbon and Typica, often prized for their sweetness and clarity, may behave differently in the roaster compared to more robust, earthy varieties like Catimor or Sarchimor.”

Why is bean density so important?

Bean density is one of the key metrics for sorting and grading coffee. It’s essentially the weight of a coffee bean proportional to its volume, which is typically influenced by the altitude at which it’s grown. Higher altitudes allow coffee to ripen more slowly, resulting in denser beans with a higher sugar content – making them more desirable to many buyers.

Density also varies between different varieties, too. Bourbon, Gesha, and Wush Wush, for instance, are generally dense beans, while robusta varieties grown at lower altitudes are less dense.

In addition to exhibiting more complex, sweet flavours, denser beans also require a different approach to roasting.

“Although it depends on roast profile, batch size, and origin, a higher density variety requires a higher start (or charge) temperature, while the opposite is true for lower density beans,” say Carina Esteves and Ishwor Maharjan, the director of operations and head roaster at Baobá Café in Lisbon, Portugal. The roaster also has locations in Brazil, where it operates a farm that it sources coffee from.

“Our blends are developed on-farm, and our team chooses varieties with similar sizes and densities to facilitate the roasting process,” they add. Significant variances in size and density will leave bigger and denser beans underdeveloped, while less dense and smaller varieties will be tipped or scorched.

“Dense coffees often have more nuanced flavour profiles at a wider range of roast levels. However, they can be easier to under-roast as they require more time and heat in the machine,” Ashlee Eastwood-Quinn, head of coffee at Rave Coffee. “The dense beans will also be less brittle when roasted and therefore produce fewer fines when grinding. Fewer fines result in even extraction of and a well-balanced flavour profile.”

Prioritising consistency with multi-variety blends

Combining similar-sized and equally dense varieties seems like a logical approach to bypass the challenges of blending beans of different sizes and densities. However, it’s not always so straightforward.

“Achieving the best results when roasting blends is often a process of trial and error. While using varieties with similar sizes and densities can, in theory, lead to a more uniform roast, the outcome depends on several factors, including the specific characteristics of the varieties and processing method,” Marc-Alexandre says. “In practice, blending varieties with similar sizes and densities makes it easier to achieve a uniform roast. Beans of comparable physical characteristics absorb and retain heat more evenly, reducing the risk of over or under-roasting some components of the blend. 

“However, uniformity in size and density doesn’t guarantee compatibility in terms of flavour,” he adds. “That’s why trial and error is so important; roasters need to experiment with how the blend components behave in the machine and ensure that the resulting flavours are harmonious.”

Regularly cupping combinations of different varieties using various ratios is the best way to ensure the flavours match and complement one another.

However, the technique used to blend different varieties also plays an important role.

“When blending a high-density washed Ethiopian variety with a low-density natural Brazilian coffee, roasting them together can be problematic,” Marc-Alexandre says. “The Brazilian beans, being less dense and often larger, roast faster, while the Ethiopian beans take longer to develop. This disparity can lead to an imbalanced cup, with the Ethiopian beans potentially under-roasted and the Brazilian beans over-roasted.”

Post-roast blending

“Some coffees might roast to a darker degree than others when exposed to the same roasting conditions,” Carina and Ishwor say. “To overcome this, roasters can blend post-roast, where they roast each variety separately to their optimum level and then mix the batches together.”

This allows for precise control over each blend component, ensuring that roasters can fully develop their unique qualities to create a balanced flavour profile.

Do certain varieties pair well in blends? 

Coffee varieties have their own unique characteristics in terms of flavour, body, mouthfeel, and aftertaste, so understanding which ones complement each other is crucial when creating a multi-variety blend.

“Some varieties naturally pair well together in blends, creating a harmonious and balanced cup that highlights their individual strengths,” Marc-Alexandre explains. “For example, African varieties like 74110, SL28, Ruiru 11, and Konkaka consistently produce exceptional results when blended. Even when sourced from different regions or continents, they blend seamlessly to create a cup with layered complexity and clarity. SL28’s bold acidity can enhance the sweetness and balance of Ruiru 11, while 74110’s floral and citrusy notes can pair wonderfully with Konka’s berry-like sweetness or herbal undertones, for instance.”

Exclusive varieties like Gesha and Sudan Rume have taken specialty coffee by storm over the last decade. Revered for their exceptional and complex cup profiles, they are often sold and marketed as single origin lots to showcase their unique flavours.

But Marc-Alexandre highlights how these varieties can also work well in blends.

“Gesha is often used to add floral notes, delicate acidity, and tea-like qualities to the cup; it pairs wonderfully with varieties that offer complementary sweetness and body,” he says. “For example, combining Gesha with Bourbon highlights Gesha’s floral elegance while adding structure and sweetness from the Bourbon. Similarly, pairing Gesha with Caturra or Catuai can balance its delicate character with enhanced body and depth.”

No variety is an island: Coffee flavour is interconnected

The flavour profiles of different varieties are inherently tied to many other factors, such as origin, processing method, altitude, and terroir. In many cases, it’s difficult to distinguish between the impact of each variable, which means roasters need to account for all of them when developing a multi-variety blend.

“Every element can impact flavour. For example, SL28 is a common variety in Kenya. If you take this coffee and grow it in Colombia, you can get a different flavour profile, even if both coffees are washed,” Ashlee says. “Kenyan washing styles are also very different from Colombia, so the flavours we associate with SL28 are so heavily tied to our associations of Kenyan coffee and processing. Therefore, we can make some assumptions when roasting and blending, but before practical experimentation takes place, we can’t be sure of anything.”

Multi-variety blends can offer roasters a point of differentiation, creating tailored and exciting flavour combinations that suit a range of consumer needs. Bean density and size are key considerations when blending multiple varieties, but factors like origin and processing method are also play an important role.

“The ultimate success of a blend depends on understanding the unique properties of each component and tailoring the roasting approach accordingly,” Marc-Alexandre concludes. “Roasting coffee is as much about science as it is about artistry and experimentation.”

Enjoyed this? Then read our article on how blends can reduce waste.

Photo credits: Rave Coffee

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