Metabolomic insights into the Arabica-like flavour of stenophylla coffee and the chemistry of quality coffee.

Stenophylla coffee, an undomesticated species from Upper West Africa, is of commercial interest due to its high heat tolerance and Arabica-like flavour. To investigate the chemical basis of flavour similarity, we analysed unroasted coffee bean samples using liquid chromatography-mass spectrometry (LC-MS) and applied metabolomics approaches to compare chemical profiles. We report similarities between Arabica and stenophylla in the relative levels of several key compounds linked to coffee flavour, including caffeine, trigonelline, sucrose and citric acid. Differences in their chemical profiles were also observed, especially in their diterpenoid and hydroxycinnamic acid profiles. We report the additional novel finding that theacrine occurs in stenophylla, which is the first record of this alkaloid in coffee beans. For stenophylla, the dissimilarities in chemical compound composition (compared to Arabica) may offer opportunities for a better understanding of the chemical basis of high-quality coffee and sensory diversification.