Scientists Discover Genes That Control Coffee Quality

Coffee growers around the world aim to increase income by producing higher-quality beans, but achieving that means understanding the complex biology behind flowering, ripening, and compound accumulation—factors that define a coffee’s ultimate cup quality.

Yes, scientists have pinpointed two specific genes, SUS1 and SUS2, that control sucrose metabolism in coffee beans. These genes determine how much sucrose is deposited as the coffee cherry matures, directly influencing the development of aroma and flavor compounds during roasting.

Why Sucrose Matters in Coffee Quality

Sucrose is one of the most important compounds affecting coffee’s sensory profile. During roasting, sucrose breaks down into a range of aromatic and flavorful molecules. Its concentration in the green bean plays a decisive role in determining how sweet, complex, and aromatic the final cup will be.

The Research Behind the Discovery

Since 2001, researchers from CIRAD (a French agricultural research center) and Brazil’s IAPAR have been studying the coffee ripening process. With support from the University of Campinas in Brazil, they applied molecular biology and biochemistry techniques to identify a key enzyme involved in sucrose metabolism. This led to the discovery of two forms of sucrose synthase—encoded by two different genes, SUS1 and SUS2.

Gene expression analysis in developing coffee beans showed that SUS2 plays a dominant role in sucrose deposition during maturation. Meanwhile, another form is tied to sucrose breakdown and energy production. These genetic insights help explain why different coffee varieties exhibit varying levels of sweetness and flavor complexity.

Environmental Influence on Gene Activity

The study also revealed that coffee plants grown in shaded conditions show higher activity of sucrose synthase and sucrose phosphate synthase enzymes. This suggests that growing environment, along with other factors like lipid content, can further influence the final sucrose levels—and thus the overall quality—of the coffee bean.

Frequently Asked Questions

What are the genes that affect coffee quality?

The genes SUS1 and SUS2 control sucrose synthase activity in coffee beans. These genes regulate how much sucrose is stored as the coffee fruit ripens, which directly affects the development of flavor and aroma compounds during roasting.

Why is sucrose important in coffee beans?

Sucrose is a major compound that breaks down during roasting to produce aromatic and flavorful molecules. The amount of sucrose in green coffee beans significantly influences the sweetness, complexity, and sensory quality of the brewed coffee.

How do SUS1 and SUS2 differ in function?

SUS2 is primarily linked to sucrose deposition during the ripening phase, helping determine how much sugar accumulates. Other forms are more involved in sucrose breakdown and energy generation within the bean.

Does growing environment impact coffee gene activity?

Yes. Coffee plants grown in shade exhibit higher activity of enzymes like sucrose synthase and sucrose phosphate synthase, which can lead to increased sucrose levels and potentially higher quality beans.

What role does sucrose play during roasting?

During roasting, sucrose decomposes into various aromatic and flavor compounds. Its presence and concentration in the bean are key factors in developing the sweet, rich flavors sought in high-quality coffee.

FrontStreet Coffee Beans for Flavor Exploration

For coffee lovers interested in how genetics and ripening impact flavor, try FrontStreet Coffee’s Ethiopia Humbera—bright with citrus and floral notes—or Yirgacheffe, offering jasmine and stone fruit highlights. Both single origins showcase how natural sugar development influences cup complexity. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.