Excelsa Coffee shows its potential.

Can an ancient coffee variety save our beans?

Climate change presents a significant threat to the future of coffee, as rising temperatures and unpredictable weather patterns are making previously suitable land no longer fit for production. To tackle this challenge, researchers and producers have three options: relocating coffee production to areas that are now more suitable, adapting farming practices, or planting new, more resilient varieties. The first two options are considered less favourable due to the disruptive impact they would cause, leaving the third option of utilizing different varieties as arguably the most viable.

Now, researchers are taking a closer look at an old coffee species that may hold the key to boosting global production. Excelsa, a variety of Liberica coffee, which is the third species after Arabica and Canephora (robusta), is showing promise for its production efficiency, resilience, and flavour profile.

In a new study published in the journal Nature Plants, lead author and coffee researcher Dr. Aaron Davis of the Royal Botanic Gardens, Kew, examines two varieties of Liberica currently growing in Africa: C. liberica var. liberica and C. liberica var. dewevrei. Previously thought to be separate species due to the difference in size of the cherries they produced, these two varieties, commonly referred to as liberica and excelsa respectively, are now understood to be part of C. liberica. Excelsa is believed by Dr. Davis’ team to be particularly noteworthy.

Once popular at the turn of the 20th century, and considered as “sitting alongside Arabica as the main coffee species of global commerce” according to the study, Liberica coffee has a number of attributes that make it an interesting option for tackling contemporary coffee production challenges. It is robust, high-yielding, with fruit that remains on the tree when ripe, it grows well in warm, lowland locations (<1,000 MASL), and is believed to have resistance to pests and diseases and drought tolerance. However, Dr. Davis and his team note that it did not taste good, which may have been due to improper post-harvest processing due to the large size of the cherries, which are roughly the size of plums with a thick outer skin, leading to improper drying.

Excelsa is primarily found in Southeast Asia, where it grows on large and thriving trees at medium elevations. Like Liberica, Excelsa beans have a unique shape, but they are slightly smaller in size.

In and around Southeast Asia, Excelsa coffee is highly valued and used in coffee blends, particularly house blends, to provide added depth and complexity to its unique fruity flavor.

According to the study, Excelsa has many of the same advantages as Liberica, with some additional key benefits. Excelsa, like Liberica, has been shown to have high yields that often surpass those of Arabica and robusta. However, Excelsa also has synchronized fruit ripening and closely clustering fruits, making harvesting easier. The size of the cherries is also a big plus for Excelsa as they are similar to those of Arabica, with a thin skin and soft pulp, allowing for easier post-harvest processing without the need for special machinery.

The flavour of Excelsa has also been positively received. In assessments of the coffee grown in Uganda and South Sudan, it was described as having a mild and smooth flavour with low to medium acidity and low bitterness, and tasting notes of cocoa nibs, peanut butter, dried fruits, Demerara sugar, raspberry coulis, figs, plums, and milk chocolate.

According to Dr. Davis, when properly harvested and processed, Excelsa coffee has a cup profile that is closer to Arabica compared to robusta, with sweet and smooth flavour and notes of various fruits, chocolate, and caramel. Although it may not have the complexity of the best Arabica, the full sensory potential of Excelsa is yet to be discovered.

The potential of Excelsa is not just theoretical. In Uganda, there are currently 200 farms growing the variety, with the number continuing to increase each year. Many farmers are switching from growing robusta to Excelsa, and some are growing Excelsa exclusively.

Although much is still unknown about Excelsa as it has been neglected as a coffee crop, the prospect of a reinvigorated coffee variety from a species separate from traditional Arabica and robusta is an exciting development. If successful, it may provide a means to maintain coffee production in current growing areas threatened by climate change and also open up the possibility for growing higher quality coffee.

The next generation of coffee plants will be an important marker in the fight to survive climate change. Image: https://coffeegeek.tv/