Enhancement of antioxidant properties from green coffee as promising ingredient for food and cosmetic industries

Abstract

Phenolic compounds are present in large quantities in green coffee and have been recognized as natural antioxidants. However, hydroxycinnamic acids such as chlorogenic acids are found mainly in the esterified form which reduces their bioavailability. Therefore, the aim of this study was to perform the biotransformation of the green coffee using Aspergillus oryzae. Green coffee was fermented under solid state at 25 °C for 24, 48 and 72 h and the phenolic compounds were extracted using a hydroethanolic solution. The antioxidant activity of the extracts was evaluated by the 2,2-diphenyl-1-picrilhidrazyl and reducing power methods, and the determination of total phenolic contents was performed using Folin-ciocalteu method. Chlorogenic acid (5-ACQ), caffeic acid and caffeine were quantified by HPLC. Green coffee extracts fermented for 24 h presented an increase of 115.7% and 66.4% of the antioxidant activity measured by DPPH• and reducing power methods, respectively. Additionally, coffee fermentation promoted an increase of 68.6% in the content of phenolics, and an increase of chlorogenic and caffeic acids. The results showed the biotransformation as a strategy to obtain an enriched extract of antioxidant compounds as promising ingredient for food and cosmetic industries.