An introduction to Robusta coffee

Robusta Coffee Beans

Definition and understanding of Robusta coffee

Coffea canephora, commonly known as Robusta coffee, is an important variety in global coffee cultivation and accounts for about 40% of the world’s coffee production. Robusta is only surpassed by its relative, Arabica, and is characterised by its strong, full-bodied flavour and caffeine content, which is almost twice as high as that of Arabica.

Robusta is mainly grown at low altitudes between sea level and 600 metres and thrives in warm, humid climates. Its cultivation is favoured for its relative simplicity and resistance to disease and pests, making it a good option for farmers. Robusta is often used in espresso blends and instant coffee, valued for its contribution to crema and richness.

Historical context of Robusta coffee

The origins of Robusta coffee can be traced back to Central and West Africa, where it was first discovered by Dutch botanists in what was then the Belgian Congo. It became known in Southeast Asia around 1900 when the catastrophic coffee rust disease devastated the coffee farms in Ceylon (now Sri Lanka) in 1869 and destroyed numerous plantations at lower altitudes on Java in 1876. Before it was cultivated commercially, Robusta had existed for centuries in the dense African forests. Its evolution from a native wild plant to an essential ingredient in espresso blends emphasises its resilience and adaptability and cements its role as a crucial element in global coffee history.

Comparative analysis of Robusta and Arabica coffee beans

Robusta and Arabica, the two most important species in commercial coffee production, show considerable differences in terms of cultivation, flavour and market preferences.

Botanical variations

Robusta beans are characterised by their smaller, rounder shape, in contrast to the larger, more oval Arabica beans. The character of Robusta beans goes beyond their nomenclature, as they are easier to grow due to their resistance to diseases and pests and can thrive at lower altitudes.

Arabica beans, on the other hand, need to be grown at higher altitudes and require more attention as they are more susceptible to disease. These differences in cultivation requirements are also reflected in the production costs: Arabica beans are more expensive to produce and therefore also more expensive for consumers.

Robusta Coffee Plants
Robusta Coffee Plants

Differences in flavour

Flavour is a decisive factor that distinguishes the two types from each other. Arabica beans are characterised by a sweeter, fruitier profile that encompasses a broad spectrum of flavours. In contrast, Robusta beans are characterised by a stronger, earthier and often bitter taste. This distinct profile makes Robusta beans suitable for espresso blends and Cafetiere coffee where intensity and bitterness are desired. Although Robusta is often perceived as a ‘cheaper’ coffee, high-quality Robusta varieties can match or even surpass the flavour of inferior Arabica beans.

Caffeine content and other attributes

The caffeine content is an important distinguishing feature between these bean varieties. Robusta beans contain almost twice as much caffeine as Arabica beans, on average around 2.7 % compared to 1.5 % for Arabica. This higher caffeine concentration contributes to the more bitter flavour profile of Robusta beans.

Robusta beans also have a higher antioxidant content, particularly chlorogenic acid, which adds to their complex profile. However, this aspect is not usually a decisive factor for consumers when choosing between Robusta and Arabica beans.

Diversity and key varieties of Robusta coffee

The most important varieties of Robusta

Robusta coffee, known for its resilience and vigorous growth, consists mainly of two varieties: Nganda and Erecta. Nganda is a shrub with a wide spread, while Erecta has a taller growth habit. In addition, the natural tendency of Robusta to hybridise in the wild has led to the creation of several hybrid varieties. These include Catimor and Sarchimor, which are often classified and marketed as Arabica, but have inherited higher disease resistance, particularly against coffee rust, and simpler cultivation requirements from their genetic Robusta ancestry.

Regional characteristics of Robusta coffee

The regional diversity of Robusta coffee beans is particularly pronounced, as each major growing region offers different flavour characteristics:

Vietnam: Often referred to as the ‘Robusta capital of the world’ and is characterised by its strong, earthy flavour, complemented by nuances of cocoa. The central highlands of Vietnam, with their ideal climate and soil conditions, are the heartland of Robusta cultivation.

Brazil: Although Brazil is primarily known for its Arabica beans, it also plays an important role in Robusta production. Brazilian Robusta, which is grown in Espírito Santo and Rondônia, is known for its smooth texture and subtle nutty flavour profile.

Indonesia: The Indonesian islands of Sumatra and Sulawesi are known for their Robusta cultivation. The Robusta beans here, which are influenced by the country’s tropical climate and volcanic soil, are often characterised by a woody flavour and a slightly smoky aroma.

India: In India, Robusta is mainly grown in the southern states of Kerala, Karnataka and Tamil Nadu. Indian Robusta is characterised by its spicy undertones and a robust, full-bodied consistency.

Uganda: Uganda, a major producer of Robusta, has its main growing areas around Lake Victoria. Ugandan Robusta is known for its milder flavour profile with chocolaty and spicy notes.

Discovery of Robusta
Discovery of Robusta

Environmental aspects and sustainability in Robusta coffee cultivation

Robusta coffee, requires special environmental conditions for cultivation and faces various challenges that affect its sustainability.

Optimal conditions for Robusta cultivation

The successful cultivation of Robusta coffee beans depends on favourable environmental factors.

Soil

The ideal soil for Robusta is loamy clay with a pH between 5 and 6.5, which provides a balanced nutrient profile and good moisture retention. Adequate levels of iron, nitrogen, phosphorus and potassium are crucial for Robusta growth and in some cases require additional fertilisation.

Temperature and humidity

The optimum temperature range for Robusta cultivation is between 22 and 30 degrees Celsius, coupled with a relative humidity of around 70%-85%. These conditions are essential for the growth and health of the coffee cherries.

Pruning and pest control

Consistent pruning, especially in the dry season, is essential for healthy growth and higher yields. Effective pest and disease control strategies are essential to minimise production losses. Integrated pest management approaches that combine biological, cultural and chemical measures are used to combat common problems such as the coffee berry borer and diseases such as coffee rust.

Harvesting and post-harvest processing

The harvesting phase is crucial for the yield and quality of the coffee. Techniques range from manual harvesting to mechanised methods, the latter being more cost effective but can compromise quality. After harvesting, the beans undergo various processing methods such as wet, dry or semi-washing, each of which affects the final flavour profile and quality of the coffee.

Robusta Coffee Research
Robusta Coffee Research

Improving sustainability in Robusta production

Sustainability in Robusta coffee production is becoming increasingly important, with initiatives focussing on improving environmental impact and coffee quality.

Environmentally sustainable farming practises

Practises such as crop rotation, cover cropping and intercropping with legumes are used to improve soil health and structure. These techniques help with nutrient management and weed control. Efficient irrigation methods are also important to ensure adequate soil moisture and avoid excessive water consumption.

Research and development

Future research efforts will focus on developing innovative methods of pest and disease control, especially those that reduce dependence on chemical pesticides. Another focus is the optimisation of irrigation techniques to combat drought and water shortages as well as the adaptation of cultivation practises to changing climatic conditions.

The Robusta plant is naturally resistant to high temperatures and drought, which gives it a potential advantage in the face of climate change. However, further research is needed to fully understand and optimise cultivation practises under changing environmental scenarios.

Robusta coffee beans in coffee blending

Robusta coffee beans play an important role in various coffee blends and improve both the flavour profile and the attractiveness of these blends.

Integration with Arabica in blends

Robusta is often blended with Arabica coffee beans and contributes significantly to the overall character of the blend. Arabica, known for its subtle and nuanced flavours, is complemented by the Robusta bean with its strong body. This synthesis results in a blend that is both balanced and rich. Blending different coffee bean varieties, even from different regions, is a cost-effective strategy.

Blending achieves a more consistent flavour by combining the particular characteristics of each variety. In espresso blends, Robusta not only improves the crema, but also provides a depth that balances the bitterness with the sweet, acidic notes of Arabica beans.

Contribution to flavour and potency

The high caffeine content of the Robusta bean is key to its strong and powerful flavour, making it the preferred choice for espresso lovers and black coffee enthusiasts. This strong flavour is beneficial in blends with Arabica as it adds intensity and complexity. In latte drinks, the robust character of Robusta contrasts effectively with the creaminess of the milk and enriches the flavour experience. The juxtaposition of the subtle Arabica flavours and the strength of the Robusta results in a blend that is both richer and more balanced.

Specific applications in different types of coffee

Robusta is used in various specific coffee preparations.

Decaffeinated coffee

Despite its high caffeine content, Robusta is preferred for decaffeinated coffee due to its strong flavour profile. The decaffeination process tends to diminish the flavour and as Robusta is more flavourful than Arabica, it is better suited to retaining the flavour after decaffeination.

Instant coffee

The prevalence of Robusta in instant coffee is remarkable. Its cost-effectiveness makes it the ideal choice for the production of instant coffee, where there can be a significant loss of coffee material.

Cold brew coffee

The cold brew technique for Robusta can improve the results of iced coffee drinks. This method reduces acidity and increases sweetness, allowing the more subtle flavours of Robusta, such as nutty and toffee notes, to come through. This property is particularly beneficial for iced coffee preparations where such nuanced flavours are desired.

WCR Research
WCR Research

Innovations and developments in Robusta coffee research

Improvements in cultivation practises

World Coffee Research (WCR) has advanced the development of Robusta coffee through various research and development initiatives. A particular focus is on breeding programmes aimed at meeting the industry’s requirements for Robusta. In 2022, the WCR launched a project to explore breeding opportunities for Robusta.

This project involved a comprehensive analysis that included global data collection, extensive literature research and consultation with industry experts to identify potential opportunities for the development of Robusta varieties. Collaboration with the Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD) has provided access to a wide range of Robusta genetic resources, enabling more effective breeding, selection and multiplication processes.

Focus on quality and flavour improvement

Improving the quality and flavour profile of Robusta coffee is another important goal. To this end, the WCR has conducted focus groups with Robusta coffee buyers to better understand their preferences and requirements. This feedback is important in order to incorporate quality improvements into the breeding programme.

Addressing issues such as supply shortages, maintaining consistent quality and improving consumer perception of Robusta are at the centre of this initiative. The discussions in the focus groups have identified opportunities for market differentiation, the introduction of new flavour profiles, product innovation and increased yields.

Driving sustainability in Robusta production

Sustainability aspects are playing an increasingly important role in the production of Robusta coffee. An important initiative of the WCR is the publication of a catalogue with around 43 Robusta varieties developed worldwide. This catalogue is a valuable resource for farmers to make informed cultivation decisions and educates the entire industry on the importance of continuous innovation through breeding. In addition, a Strauss-funded project in Uganda is focussing on the dissemination of disease-resistant Robusta varieties. This project aims to increase farmers’ incomes and promote sustainable agricultural practises.

These initiatives show that improving Robusta coffee in terms of production efficiency, quality and environmental sustainability is becoming increasingly important. As the industry evolves, research and development in Robusta coffee cultivation will make an important contribution in the coming years that can improve both the quality of coffee and its environmental footprint.