Antioxidant Activity of Commercial Soluble Coffees

Abstract

A product of easy preparation and high added value, soluble/instant coffee is obtained by drying the aqueous extract of roasted coffee and presents a high amount of bioactive compounds. The aim of the study was to evaluate the antioxidant activity of 33 Brazilian commercial soluble coffees considering the radical scavenging activity (via the ABTS method) and the reducing capacity (via the Folin–Ciocalteu method). Soluble coffees of several brands and types (regular, gourmet, and decaffeinated), subjected to different drying processes (agglomeration, atomization, and freeze-drying) (n = 85), were evaluated. In general, regular and decaffeinated soluble coffees presented high antioxidant activity. The reducing capacity ranged from 9.9 to 15.4 g of gallic acid per 100 g, while the radical scavenging activity ranged from 20.4 to 37.0 g of Trolox per 100 g. Good repeatability—with coefficients of variation of 2.4% for Folin–Ciocalteu and of 5.2% for ABTS—and high correlations between the values of antioxidant activity obtained by both methods (r = 0.66) were observed. Gourmet coffees presented less antioxidant activity compared to the regular samples. No correlation was verified between drying processes and antioxidant activity.