May 18, 2021

“Challenging and enriching to study”: Exploring robusta coffee’s genetic diversity


Even though there are more than 120 known species in the Coffea genus, just two, arabica and robusta, account for more than 99% of all global production. Within that, robusta accounts for approximately 30 to 40%, and is broadly considered to be of lower quality than arabica. 

Despite the fact that there is limited discussion about its provenance and history, the genetic diversity of robusta is incredibly broad. This means there is a largely unexplored world of robusta varieties out there, many of which have not been formally recognised.

To learn more about robusta’s genetic diversity and its many varieties, I spoke to three coffee professionals who work with fine robusta coffee. Read on to find out what they said.

You may also like our article exploring the connection between canephora & robusta.

Canephora, conilon & robusta: A history & overview

Coffea canephora is native to western and central sub-Saharan Africa, where it has grown indigenously for an unknown amount of time. 

One of the earliest recorded discoveries, however, can be traced back to Belgian-occupied Congo – now known as the Democratic Republic of Congo – in the 1800s. Not long after, however, the species was also found in Uganda, specifically in the forests surrounding Lake Victoria.

Lucas Venturim is a fifth-generation coffee producer and the Director at Fazenda Venturim, a fine robusta coffee farm in Espírito Santo, Brazil. “[There are] two groups of plants from the same species (Coffea canephora) found in different areas of Africa,” he tells me. “Botanically, [they are] called ‘populations’ because you can have countless varieties in each group. 

“One population is called robusta, which was found first in Uganda. The other is called conilon, now grown in Brazil, but found first in the Kwillou River Valley in the DRC. It was later found throughout central Africa. The word ‘Kwillou’ was adapted informally in Brazil and later became ‘conilon’.”

Through the 19th and 20th century, the canephora species was summarily introduced in other countries around the world, perhaps most notably in southeast Asia. It became popular on coffee farms thanks to its overall resilience and ability to grow in a number of different environments, unlike arabica.

“Canephora [can] adapt to a range of different growing conditions,” Lucas explains. “[It can grow] from sea level to 1,500 m.a.s.l., in rainy regions and in very dry areas, and so on.”

Cleia Junqueira is a roastmaster at Coffee Planet in Dubai. She has been a certified Q robusta grader (or R grader) since 2017. 

“Coffea canephora has two main varieties: robusta and nganda,” she says. “The difference [between them] is where the farms are [located] and how [they adapt] to climate and latitude. [They are] mostly grown in Vietnam, [but] also in India, Africa, and Brazil.”

Genetic diversity

Denise Bustamante is the Process and Quality Manager at Dublinsa SA, which produces fine robusta at Hacienda Legrand, a farm in Santa Elena, Ecuador. She is a Q robusta and arabica grader, which she says allows her to “respect and identify the nuances of both species”.

“Robusta is more diverse [than arabica], yet it is challenging and enriching to study,” she says. “There is also still little information about it,” 

One of the biggest reasons that the canephora species is so genetically diverse is that it cannot pollinate itself. 

“Canephora depends strongly [on] cross-pollination,…[so] the genetic basis is almost endless,” Lucas tells me. “This effectively means that [the plants can] have many different genetic loads – [for example], different ‘fathers’ [but the] same ‘mother’.”

This means there is a theoretically infinite number of wild canephora varieties growing in coffee-producing regions across the globe. 

In addition, Lucas says the lack of self-pollination means that farmers often need to plant a number of different varieties at once. “Cross-pollination means that you [need] to plant at least 10 to 15 varieties in the same area,” he explains.

Denise tells me that Dublinsa SA organises the cross-pollination of their robusta varieties to produce the most productive and best quality plants. 

“In 2007, along with COFENAC, a coffee research institution, we carried out a project to select, adapt, and identify the best [robusta variety] clones in Ecuador,” she tells me. “With these, we developed Ecurobusta 01 [by] selecting plants based on phenotype and genotype, following DNA mapping analysis. This allowed us to choose those which expressed desirable characteristics under specific agroecological conditions.”

Specific canephora varieties can be identified through a number of different visual plant attributes (such as the size and shape of the leaves, for instance). Over several years, Denise says they cultivated a “clonal garden” with “elite clones”, gradually taking pollen from specific clones to develop a desirable “polyclonal hybrid”.

“Cup quality was [important],” she tells me.” After that, we were able to launch our Café Legrand 100% single origin robusta and 100% Ecurobusta [coffees].”

Robusta’s market position

Canephora currently comprises between 30% and 40% of global coffee production. Vietnam is the world’s largest individual producer by volume; according to Statista, the country grew approximately 30.2 million 60kg bags in the 2019/20 crop year. 

However, canephora production has increased significantly around the world in recent years, particularly in Brazil’s conilon population. This has been reflected in the number of different varieties the country has introduced in the 21st century.

Lucas says: “The most grown variety in Brazil is Conilon Vitória, which was released in 2002. After this, [there is] Conilon Diamante, Conilon Centenário and Conilon Jequitibá, [all] released in 2012.”

This popularity has been reflected in the fact that Brazil’s conilon production levels have been increasing overall since the year 2000, aside from a drop from 2016 to 2018. 

“All of [these varieties] were selected for a range of criteria, including productivity, pest and [drought] resistance, and cup quality,” Lucas adds. “The aim is to find which variety is best for each farm and its client.”

In Ecuador, producers grow both arabica and canephora, albeit on a small scale. This is why there is a growing focus on adding more value on the production side (by cultivating specialty arabica or fine robusta).

Denise explains that most of the canephora grown in Ecuador is robusta. She says that as it has grown there for almost 70 years, producers have more knowledge about how to grow it, and the adapted plants are more resistant to pests and diseases.

“Ecuadorian robusta used to only be used for instant coffee, but now the market is evolving,” she says. “There is higher quality robusta coffee accessing the specialty [sector] on a small scale.

“We (Dublinsa and Hacienda Legrand) are pioneers in Ecuador, designing processing methods that create and develop new and more flavours and positive attributes as a side study from our time developing Ecurobusta. We know quality is achievable, and we know that it is a reality.”

How are quality & production improving?

We use the word “specialty” to refer to high-quality arabica coffee, but there is separate language used for higher quality canephora. “We do not [say] specialty-grade robusta, instead we call it ‘fine robusta’,” Cleia explains.

Fine robusta is defined as “robusta coffee that is free of primary defects and exhibits unique and desirable characteristics unique to a microclimate of origin”.

As a species, canephora has a reputation for being too low quality to be palatable on its own. “Commodity-grade [robusta] mostly [has] notes of potato, garden peas, pepper, cedar, pipe tobacco, toasted bread, roasted peanuts, earth, medicine, smoke, rubber, or straw,” Cleia says. “It is woody, salty, and astringent.” Broadly, these flavours are not considered to be desirable.

However, improvements throughout production and post-harvest are leading to higher quality. Denise points out that if farmers take greater care with their crops, it will yield better tasting results for the consumer, just as is the case with arabica.

“Poorly treated coffee, whether arabica or robusta, will express undesirable notes,” she says. “[With] fine robustas, you can get caramelised notes, fruits, spices, interesting acidities – such as malic, phosphoric, and lactic – intense fragrances, long-lasting aftertastes, and round, heavy, and velvety bodies.”

The genetic diversity of both the conilon and robusta populations can also create disparities in plant characteristics, which can have a significant impact on how the beans are processed. “Because of the plant’s complex genetics, the seeds are [often] not uniform, even in the same plant,” Lucas explains. “Thus it becomes necessary to [sort the beans based on size during] dry milling.”

As with arabica, innovations in processing can also lead to a wider range of unusual flavour profiles for robusta and conilon, helping them appeal to a wider audience.

“We do mostly pulped natural, [which produces] great quality with great consistency,” Lucas says. “However, we also do some naturals, honeys, and since 2016, fermented coffees. All the lots are traceable, and we cup all of them separately to assure quality [for] the customer.”

Fine robusta & its wider market potential

It’s vital to understand that canephora is fundamentally different to arabica, and that each variety is unique in its own way. 

“Canephora has more soluble particles available, [so] usually you have more body, [and it can easily] get overextracted and bitter,” Lucas notes. “It’s important to adapt or use different extraction parameters [to achieve high quality results].”

He goes on to tell me that the same is true for roasting canephora beans. “Researchers studying the cellular structure of canephora [found that it] is [more] rigid [and] takes more energy to transmit heat [throughout] the bean,” Lucas adds.

This is a key challenge for fine robusta. If robusta or conilon are roasted with the wrong profiles, the inherent characteristics of the bean won’t be able to shine through, and perceptions won’t improve.

Denise adds that “genetic diversification is crucial” for fine robusta if it is to thrive.

“[This will help] correlate the variety for a specific location, purpose and market,” she explains. “For example, do you want to have [high] cup quality, high yields, or a pest resistant plant?”

For example, she tells me that Ecurobusta has been designed to cover all of these variables. Going forward, she says that more studies will be necessary to understand genetic diversity, gene expression, and environmental triggers in canephora cultivation.

Lucas notes that these improvements in quality are key. “[The] specialty market is so important to robusta growers’ families,” he says. “Now they [have a] different pathway to sustainability.”

The land available for arabica production is expected to decrease by as much as 50% by 2050 due to climate change. This is already pushing farmers to search for higher elevations to get the best environmental conditions for cultivating specialty coffee. 

If robusta varieties are able to grow at lower elevations and yield desirable cup profiles, there may be less of a necessity to “chase” optimum arabica temperature ranges into higher altitudes.

“Openness in the industry is crucial to give premium and fine robusta an opportunity to be a solution,” Denise concludes. “This will help the families involved in coffee production to be more sustainable and profitable, and support customers looking for new sensory experiences.”

While fine robusta is a comparatively small trend that is still in its infancy, the genetic diversity of the canephora plant represents a number of opportunities for farmers across the coffee sector.

Denise says that the most important thing, however, is just to recognise that canephora and arabica are fundamentally different. “Don’t expect to cup or taste a robusta like an arabica,” she says. “Allow high quality robusta to express its own personality and story.”

Enjoyed this? Then read our article on whether or not fine robusta can be considered quality coffee.

Photo credits: Fazenda Venturim, Guillermo Lizarzaburo

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