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> What are the compounds in green coffee beans that change depending on the maturity of the coffee cherries?

Research & Technology

Pursuit of superior flavor and taste What are the compounds in green coffee beans that change depending on the maturity of the coffee cherries?

Coffee, a beverage enjoyed around the world, is made through roasting and extraction of green coffee beans. Suntory has succeeded in clarifying the key compounds in green coffee beans that change according to the maturity of the coffee cherries.

With the earnest desire to manufacture superior flavor and tasting coffee beverages, Suntory is forging ahead with research by looking at plant materials.
Coffea produces brightly colored cherries whose color changes as they ripen. The seeds of those coffee cherries become green coffee beans that are the raw materials for coffee, but the changes in the green coffee beans dependent on maturity were still not clear.
For that reason, we began research focusing on the metabolites in green coffee beans that change according to the maturity of the coffee cherries.

Roasted coffee beans (left) and raw beans before roasting (right)

There are numerous compounds in green coffee beans, some of which exist in very few numbers. Since some compounds significantly impact the coffee’s maturity regardless of the amount contained in the coffee beans, to search for compounds that are key to maturity a cutting-edge analytical technology was required that is capable of detecting even minute amounts. Therefore, we newly implemented a highly precise technology called metabolomics* that is used in medicine when diagnosing diseases from traces of blood and saliva. This technology makes it possible to comprehensively detect changes in the amounts of thousands of compound types, including those that exist in minute quantities.

*This technology comprehensively and objectively analyzes metabolites, which are chemical compounds produced in plant and animal cells through biological activity.

We harvested coffee cherries of different maturities from nine varieties grown in a coffee plantation of collaborative research institute, then analyzed the compounds in the green coffee beans using metabolomics.
Analysis results showed that tryptophan, an amino acid, is contained in green coffee beans from immature cherries, regardless of the variety, and that the amount decreases as the cherries ripen. Though it was known that tryptophan is the precursor to the growth hormone called auxin in rice plants and corn, this research discoverd for the first time in the world that it is also an important compound in the maturation process of coffee cherries. Furthermore, we also found that the thermal decomposition of tryptophan gave indole and methylindole, which cause an unpleasant immature odor in the roasting process.

Coffee trees at the Hawaii Agriculture Research Center

Nine cultivars of harvested coffee fruits at four levels of ripeness

For manufacturing superior flavor and tasting beverage, understanding the nature of plant materials is important. We understand the mechanisms of substances and phenomena, and cooperate on the project with manufacture teams. Based on fundamental principles, we challenge to develop practical technologies that lead to new manufacturing. We are discovering the hidden potential of nature’s gifts and enhancing the attractiveness of materials to contribute to the creation of new value.

Analysis of minor components using precise analytical devices

Related link: [News Release] World's First Elucidation of the Strong Correlation between Tryptophan in Coffea Arabica Green Beans and the Maturity Level of Coffee Cherries, a Determinant of Coffee Flavor Quality (Sept. 11, 2014)

* The department name, title, and photo are as of the time of the production (interview).