Elemental extraction factor from ground to drinking coffee as a function of the water temperature

Abstract

Several factors influence the elemental composition of drinking coffee including the method of preparation, the grain size of the ground coffee and the water quality and temperature. In the present study, the extraction factor of elements from ground coffee during the drip brewing process was evaluated as a function of the water temperature. Drip brewing coffee was prepared using Brazilian ground coffee and mineral water temperatures varying from 20 °C to 80 °C. Samples of ground and spent coffee were prepared for each temperature and analyzed with the Particle-Induced X-ray Emission (PIXE) technique. The results indicate different extraction factor patterns for each element despite some similarities among elements were observed. The extraction for K and P from the ground coffee increased linearly up to the water temperature of 45 °C, then reduced from 45 °C to 70 °C, with a slightly increase at 80 °C. Cl and Rb also seem to have similar extraction factor patterns with different extraction levels for each temperature. The absorption of elements from the water by the ground coffee was observed for Ca, Si and Cu. Moreover, K and Cl have the highest extraction ratios from ground to drinking coffee for all temperatures.