Susana Andueza at the University of Navarre in Spain explored a range of beans, grindings, water pressures, coffee/water ratios and the antioxidant power of coffee in a bid to understand all the factors that could influence the preparation of expresso coffee.
"The arabica variety had lower antioxidant capacity than robusta and the highest values of antioxidant capacity were obtained with torrefacto roast," said the researcher.
On the other hand, a study with coffee model systems was carried out in order to know which compounds (caffeic acid, glycine and sucrose) have a key role on the antioxidant capacity of coffee.
For her doctoral paper Influence of technological variables on espresso coffee quality. Antioxidant and pro-oxidant capacity of coffee, Andueza investigated the effects of hot water temperature (88, 92, 96 and 98?C), water pressure (7, 9 and 11atm), grinding grade (coarse, fine and very fine) and coffee/water ratio (6.5, 7.5 and 8.5g/40mL) on the quality of three type of EC (Arabica, Robusta Natural Blend and Robusta Torrefacto Blend) in order to select the optimal conditions.
"The technological conditions selected were 92?C and 9 atm. Moreover, it was observed that for preparation of EC with torrefacto roast a coarser grinding grade and lower coffee/water ratio than in natural roast was required," said the Spanish scientist.
Full findings can be found through the Basque research centre.