Determination of Phenolic Content and In-Vitro Antioxidant Activity of Coffee and Study of Some Affecting Factors

Abstract

Coffee is one of the most popular beverages in the world due to its distinctive flavor and taste. Coffee has many beneficial effects on health that are attributed to its phenolic content. The chemical composition of coffee could change depending on the type and origin of coffee, as well as depending on its roasting conditions and preparation method, which consequently changes coffee content of bioactive compounds. This research aims to determine the phenolic content and antioxidant activity of several kinds of coffee available in the local market. It also aims to study the effect of some factors on the coffee phenolic content and antioxidant activity, such as the origin and the degree of roasting, in addition to the boiling time during the preparation of coffee drink.

The phenolic content in the studied coffee samples ranged between 1.91 ± 0.12 and 7.09 ± 0.5 mg GAE/ml coffee drink, while the antioxidant activity ranged between 16.63 ± 1.11 and 64.63 ± 5.21 μmol Fe+2/ml coffee drink. The antioxidant activity increased with increasing phenolic content, the Brazilian coffee had a higher phenolic content and antioxidant activity (4.91 ± 0.480 mg GAE/ml, 43.58 ± 13.26 μmolFe+2/ml) compared to Indian coffee (3.6 ± 0.234 mg GAE/ml, 28.64 ± 5.24 μmol Fe+2/ml). The study found that the phenolic content and antioxidant activity decreased by increasing coffee roasting as well as by increasing heat treatment during the preparation of coffee drink.

Key Words: Coffee,  Phenolic Content,  Antioxidant Activity,  Roasting Degree.