Elimination of tryptamines from green coffee by supercritical CO2 extraction

Supercritical CO2 (SC-CO2) extraction is commonly used to eliminate caffeine from coffee beans. In this work, the feasibility of tryptamine elimination is considered as a further objective of the process. SC-CO2 extraction process parameters (eg, pressure, CO2 flow rate, water content) were studied to obtain tryptamine reduction, starting from those used in supercritical decaffeination. A good compromise, in terms of tryptamine residue in coffee beans, and process feasibility and selectivity, was found operating at 280 bar and 0.8 kg/h CO2, at a starting H2O content in coffee beans of 20% w/w. Using these process conditions, a tryptamine residue of 218 ppm (ppm) was measured in coffee beans after 18 hours of processing. A negligible effect on process selectivity and tryptamine yield was obtained by changing the CO2 flow rate and the initial water content. However, working at an initial water content of 30% w/w and using wet CO2 (CO2 plus 3% w/w water), a tryptamine residue of 107 ppm in coffee beans was obtained, but industrial complexity and costs increased.