Valorization of coffee parchment waste (Coffea arabica) as a source of caffeine and phenolic compounds in antifungal gellan gum films

Coffee parchment waste (CP), which is obtained during dry coffee (Coffea arabica) processing, is a coffee by-product that has been rarely studied nor efficiently utilized. Thus, the extraction conditions, phenolic composition, antioxidant activity of CP extracts, and their application as antifungal additive in gellan gum based films were analyzed in this work as an alternative in bioactive food packaging. Gallic, chlorogenic, p-coumaric, and sinapic acids along with caffeine were identified in the CP extracts by high performance liquid chromatography coupled with diode array detection. The optimum extraction conditions were found at 75 °C with a liquid/solid ratio of 41 using 70% of aqueous ethanol as solvent. The gellan gum film added with CP extract showed growth inhibition against Fusarium verticillioides, Fusarium sp., and Colletotrichum gloeosporioides, especially at the highest CP extract concentration (8 mg cm⁻²). The addition of the CP extract into a gellan gum film, modified its physicochemical, mechanical and structural properties, when compared with a film in the absence of any additives, and enhanced its potential use for food preservation due to its antifungal activity.