Interfacial properties of coffee oils

The liquid-liquid interfacial properties of coffee oils extracted from roasted coffee have been investigated for the first time. Oils from roasted coffee of different botanical species and geographical origins as well as from roasted coffee blends and decaffeinated roasted coffee were characterized. The interfacial tension (IT) equilibrium values were compared with those of common vegetable oils. Both IT values and dynamic behaviour reflected the presence of particularly efficient surface-active compounds which make roasted coffee oil easily emulsifiable in aqueous media. Caffeine significantly contributes to lower IT of roasted coffee oil. Arabica coffee oils showed a dynamic behaviour characterized by the tendency to reach equilibrium in longer times in comparison to Robusta coffee oils. Also, the influence of the interfacial properties of roasted coffee oil on sensory and functional properties of coffee brews, such as espresso coffee, was discussed.