Influencia del tueste torrefacto sobre los principales componentes del café y su capacidad antioxidante y pro-oxidante

Zusammenfassung

The development of Maillard reaction products in the conventional roasted coffees has been widely described. However, although sugar is known as promoter of the Maillard reactions, no studies have been carried out on torrefacto roasted coffees that are roasted with added sugar. Taking into account the well documented antioxidant capacity of Maillard reaction products, such as melanoidins, and the suggested capacity of some volatile compounds derived from Maillard reactions, it can be expected a higher antioxidant capacity in Torrefacto roasted coffees than in conventional ones. Thus, the general aim of this work was the study of the influence of the Torrefacto roast on the main coffee compounds and on the antioxidant and pro-oxidant capacity. In order to reach the general aim four partial objectives were established. Firstly, the study of the coffee consumption habits of the Navarra population and the influence of age and sex. Secondly, the study of the influence of the Torrefacto roast on the main compounds of ground roasted coffee and on the antioxidant and pro-oxidant capacity. Thirdly, the study of the influence of the Torrefacto roast and the brewing procedure (filter, plunger, moka and espresso) on the main compounds of coffee brew, and on the antioxidant and pro-oxidant capacity. And finally, the influence of the Torrefacto roast and the most commonly brewing procedures on the coffee aroma and the interaction between the most abundant coffee brew compounds and some volatile compounds. Roasted coffee with high percentages of torrefacto roast had stronger antioxidant and lower pro-oxidant capacities than conventional roasted coffees. Positive and significant correlations between browned compounds, trigonelline, 5-CQA and cafeic acid content with the antioxidant capacity measured by both DPPH¿ and redox potential methods were found. Torrefacto roasted coffees showed a lower amount of volatile compounds than conventional roasted coffees. Identified volatile compounds showed negative significant correlations with the antioxidant capacity. Coffee brews from torrefacto coffee blends were more antioxidant than those extracted from conventional ones. Coffee brews extracted by espresso machine were more antioxidant than those extracted by mocha, plunger, and filter ones. Coffee volatile profile was affected by both the roasting process and the brewing procedure. Using GC-olfactometry, it could be possible to identify 34 volatile compounds of high odor impact in coffee brews. This method allowed us to identify new odorant compounds in brew coffee, like the octanal.