[S4,E2] Weekly Coffee Report

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Liberica coffee could contribute to the diversity, resilience, and sustainability of the global coffee industry. This week I talk about an article and research paper about it.

Researchers reveal new insights into the history of Liberica coffee - Global Coffee Report

Ona Coffee’s Hugh Kelly makes Semi Finals of WBC using Coffea Eugenioides species and compound chilling - BeanScene

Research paper

Davis, A. P., Kiwuka, C., Faruk, A., Walubiri, M. J., & Kalema, J. (2022). The re-emergence of Liberica coffee as a major crop plant. Nature Plants, 8(12), 1322–1328. https://doi.org/10.1038/s41477-022-01309-5



Critically, our research highlights a key disadvantage of farming large-fruited Liberica. Due to the thick, tough pulp of the large fruits, it can take up to twice the amount of fresh cherry to produce the equivalent weight of clean coffee compared to Arabica. Unfavourable conversions, otherwise known as the outturn, are critically important for famers because they incur increased costs, particularly for harvesting, transportation, and processing.

Outturn defined: “…a total amount of goods or services produced during a particular period of time” Cambridge dictionary

Economic Output — The quantity of a product that a company, sector , or economy can produce over a limited period of time.

C. excelsa

a botanical variety of Liberica (as var. dewevrei)

Of particular note is excelsa coffee (C. excelsa) from Central and East Africa, which is now mostly regarded as a botanical variety of Liberica (as var. dewevrei).

  • high yields at more than 1000 kilograms per hectare of clean coffee
  • the ability to withstand pruning
  • resistance to a range of diseases and pests
  • and tolerance to drought and low temperatures.
  • fruit and seeds were identified as being of an equivalent size to Arabica (enables satisfactory outturn)

Uganda and South Sudan have recently experienced a localised and yet dramatic upscaling of excelsa.

The shift appears to be linked to production issues with robusta, and particularly the increasing occurrence and severity of disease and pests, and the changing climate.

“Farmers are choosing excelsa coffee because it’s easy to grow, apparently more tolerant to disease and pests than robusta, and is high yielding,” she says. “Each tree is capable of yielding up to around eight kilograms of clean coffee, and very old, ‘mother trees’ can produce in excess of 40 kilograms.” Dr. Catherine Kiwuka, from the National Agricultural Research Organization in Uganda, co-author of the research

There is currently no recognised market for excelsa coffee in Uganda. Most of it ends up mixed with robusta.

Emergent cultivation

Emergence — “Spontaneous coming together of a group to perform a task. The group self directs its course of action without external directives.” Tejas Article : Insights from Complexity Theory: Understanding Organizations Better

[T]he preference to plant excelsa (over robusta, or other coffee) has been farmer-led in both countries, rather than based on advice from either external stakeholders or intervention agents.

Secondly, excelsa is an indigenous plant of Uganda and South Sudan, and the planting stock being used appears to have been taken directly from forest to the farm. Ugandan farmers say that it came from the forest but has been with them for some generations, and only recently used as a crop species.

“Liberica” use in literature

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This is the weekly coffee report from oil slick coffee. Each week, I find a few coffee stories that pique my interest and discuss how I make sense of the story. In the previous episode, I talked about coffee production as far north as Sicily and what that could mean for the industry. This week, I’m going to talk about Liberica and the ongoing arms race between pests, diseases, and climate-change, and farmers.

The article is titled "Researchers reveal new insights into the history of Liberica coffee." And it’s published by the global coffee report. The article is about a research paper titled "The re-emergence of Liberia coffee as a major crop plant." By Aaron Davis, Catherine Kiwuka, Aisyah Faruk, Mweru Walubiri and James Kalema and I do apologize if I butchered those names and the pronunciations.

Before we dive into the article, we need to get a little technical. Both the paper and the article talk about different varieties within the species of Liberica. The term Liberica is a scientific classification of a species. Arabica and canephora, which is the scientific name for robusta are also names of species.

Within the classification of species are subclasses called varieties. And Catuai, Cattura, and Typica are all examples of varieties of the species Arabica that you’ve probably heard of. So like Caturra is a variety of Arabica, excelsa is a variety of Liberica. And that means that all excelsa trees are Liberica, but not all Liberica trees are excelsa.

If you think about it in terms of pyramid shaped hierarchy, you have coffea, or coffee near the top and that’s a genus. And then Arabica and Robusta and Liberica are all below coffea but lateral to each other. Then below each of those. You would have varieties.

Genomics is allowing scientists to better understand the genetic relationship of coffee species to each other, and to organize them more accurately into these lineages. This will help the research community to better understand what effects a given species’ ability to resist pests, diseases, and climate-change and that can help inform farmers as to which species are best for sustainable production.

Now for some history from the article. According to the article, Liberia was more widely cultivated in the late 1800’s but with mixed success. It was used specifically as an emergency response to a rust outbreak in Sri Lanka in the early 1870s. However, the enormous expansion of the cultivation of Arabica at the end of the 19th century, eventually crowded out Liberica as a commercially viable species.

Fast forward to modern times. And some researchers are now exploring lost or forgotten species to include within Liberia with a goal of broadening or diversi… diversifying the coffee crop portfolio.

That term, the coffee crop portfolio is something the authors of the research paper discuss.

This is a quote from the paper.

"The idea of broadening the coffee crop portfolio with new cultivars, hybrids and alternative species, including underutilized crop species is receiving renewed attention with a focus on forgotten or underutilized species, particularly those that were once cultivated and exported at scale. " End quote.

So Liberica may also help widen the cultivation area of coffee. The authors of the paper talk about the coffee growing frontier. Here’s another quote from the article. I’m sorry from the paper.

"As Liberica became established there was even the notion that it could replace Arabica and open up the coffee growing frontier due to its ability to grow in warm low elevation environments, as opposed to the cool tropical high elevation conditions required for Arabica." End quote.

This notion of a coffee growing frontier is interesting to me. And it’s in context with last week’s episode in which I talked about coffee grown in Sicily.

Now for some quick facts about LIberica, and this is from the article and also from the research paper, because the article is informed by the paper. But the quick facts are: it can be grown in low elevations and the paper mentioned sea level, which is pretty important. It’s tolerant of poor soil. And Liberia is quote, "hardy, deep-rooted, and quick-growing with the potential for excellent yields ." End quote. And those are all qualities important to producers.

Liberica was even showcased at the 2021 World Barista Championships. Ona Coffee’s Hugh Kelly made it to the semi-finals by using a blend that included a 50% blend of Liberica.

Liberica is cultivated in Uganda, Malaysia, the Philippines and parts of Indonesia. In fact, I was shown a Liberia plant in Indonesia in my time there and it was in a wild plot that was not actively cultivated. And, uh, I do remember the farmer showing it to me with some pride and saying, we have this Liberica here.

And as previously mentioned, Liberica gained a major foothold in cultivation as a cultivation, as a response to coffee leaf rust outbreak in Sri Lanka. So we know that it has some resistance to coffee leaf rust.

This is a quote from the research paper. "According to farmers growing excelsa in lowland, Uganda, this coffee, referred to by farmers using local names or more recently as just Liberica, has been a minor element of their farms for many decades, perhaps generations. And originally it came from the forest. Upscaling of excelsa over the last 20 years in Uganda, in particularly over the last 10 years or so, appears to be the result of production issues with robusta and particularly the increasing occurrence and severity of disease especially coffee wilt disease, drought and pests, particularly, particularly stem and twig borders." End quote.

So in other words, farmers are already looking to different breeds of coffee and their never ending battle with pests, diseases, and chain and a changing climate.

What does it taste like? This is a quote from the paper: "[E]xcelsa produces a sweet, mild, smooth coffee of low acidity and bitterness and a range of flavor notes, including various fruits, chocolates, and spices. Some have described excelsa as, quote; "the Merlot of the coffee world" [end quote]

So what’s the key takeaway? Well, I’d say that the key takeaway from this is that in a changing climate, quote "Liberica and excelsa offer almost ready-made crop options." and that’s a quote from the research paper. Farmers and other value chain actors are already perceiving Liberica as a useful addition to a given portfolio of coffee offerings.

This includes the demand side of the chain in the form of diversity in coffee flavors, blends, et cetera. But also the supply side in the form of genetic diversity in cultivated crops, green, un-roasted coffee bean offerings, et cetera.

Liberica also can help farmers achieve climate adaptability. It can produce fruit at economic levels at lower altitudes than Arabica and rabusta and possibly with a beverage quality somewhere between the two.

It is also disease resistant. Excelsa has partial resistance to coffee leaf rust, one of the most important diseases affecting coffee plants around the globe. It also has nematode resistance and possibly resistance to coffee berry borers, according to the paper by Davis, et al.

Is Liberica a silver bullet? No, not on its own. Nothing is. But it certainly warrants further research and consider consideration as another option available to increase the diversity, resilience and sustainability of the global coffee industry.

I have provided links to the articles and other resources in the show notes. Thank you for listening and stay tuned to radio free coffee.