TITLE : Influence of coffee / water ratio on the final quality of Espresso Coffee . RUNNING TITLE : Coffee / water ratio on Espresso Coffee quality

Espresso Coffee is a poliphasic beverage which physicochemical and sensory characteristics obviously depend on both the selection of ground roasted coffee and the percolation process technical conditions. The aim of this work was to evaluate the influence of coffee/water ratio on the physicochemical and sensory quality of espresso coffee. Furthermore, the influence of botanical varieties (Arabica and Robusta) and the type of roast (conventional and torrefacto) on the selection of coffee/water ratio was studied. The relationship between pH and acidity intensity perception was discussed as influenced by coffee/water ratio, type of coffee and roast. The optimization of other technical parameters in previous works seemed to minimize the influence of the increase of coffee/water ratio on the extraction of soluble and solid compounds. In fact, only some sensory attributes, such as bitterness, astringency and burnt, acrid and earthy/musty flavors were proposed as relevant to the selection of 6.5g/40mL or 7.5g/40mL in conventional roasted coffees (Arabica 100% and Robusta blend), and 6.5g/40mL in Torrefacto roasted coffees. On the other hand, the addition of sugar during roasting process in torrefacto roast coffees seemed to contribute to a higher generation of acids, melanoidins and other compounds by Maillard reaction or caramelization which led us to the selection of the lowest coffee/water ratio.