The coffee is a brown color powder that has a bitter taste. It is a member of the purine derivative methylated xanthines. It is a principle source of caffeine. After digestion, of caffeine in the body it get rapidly absorbed in the blood stream.
The coffee is a moderately soluble substance thus some components remain hydrophobic when dissolve in water or milk. These components form a layer over the surface of the fluid.
Based on the above description, a hydrophobic substance is the substance which can be seen as a film over the black coffee.
