CAFEÍNA, COMPUESTOS FENÓLICOS Y ACTIVIDAD ANTIOXIDANTE EN GRANOS DE CAFÉ ORGÁNICO (Coffea arabica, var. Caturra) OMETIDOS A TRES TIEMPOS DE TOSTADO, NIRGUA, ESTADO YARACUY, VENEZUELA.

From the roasted coffee bean (Coffea arabica), one of the most consumed beverages in the world is obtained, constituting a functional product thanks to its diversity of biomolecules. The objective of the research was to determine the effect of three roasting times on the concentration of caffeine, phenolic compounds and antioxidant activity in artisan green coffee beans. The beans were roasted at 250°C, at times of 10, 12 and 14 min, characterized as light, medium and dark roast. The analytes of interest were determined by UV/Visible molecular absorption spectrophotometry and the 2,2-diphenyl-1-picrilhydrazil free radical method (DPPH) and the iron reducing power test (FRAP) were used for antioxidant activity. The analyses showed that the caffeine concentration did not vary significantly in the three types of roasts. Statistical difference was observed regarding the content of phenolic and flavonoids compounds (p < 0.05). In relation to the antioxidant activity, the water extract of grains with medium roast presented the highest antioxidant power (DPPH = 85.34%, FRAP = 113.32 ± 0.90 µmol Fe+2/g CM). Although the roasting temperature and time vary according to each company and independent coffee grower, it is concluded that the roasting process represents a fundamental step in the expression of compounds with antioxidant activity. [ABSTRACT FROM AUTHOR]