Antioxidant capacity, bioactive compounds in coffee pulp and implementation in the production of infusions

Abstract

BACKGROUND The main by-product of the coffee production chain is pulp; if it is not properly disposed of, it represents a serious environmental problem. Some studies suggest that this pulp can be used as a source of important compounds. The aim of this study was to evaluate the content of bioactive compounds present in coffee pulps and also to prepare a functional drink-type infusion to propose an alternative use of this by-product. METHODS In coffee pulps (Coffea arabica, var. Colombia and Caturra), the effect of the tem- perature and the extraction type over the content of total polyphenols, total flavonoids, condensed tannins and phenolic acids were determined. Moreover, the antioxidant activity by ABTS, ORAC and FRAP methodolo- gies. With the best pulp, an infusion-type hot drink was prepared at 80°C. Finally, sensory assessment was performed. RESULTS The best conditions to perform the metabolite extraction were room temperature and HCl 1%. The highest trapping capacity of the cationic radical ABTS+* was 24 782.93 μmol Trolox Equivalent per 100 g of pulp, ORAC 57 087.82 μmol Trolox Equivalent per 100 g of pulp and FRAP 806.93 mg of ascorbic acid equivalent per 100 g of pulp. For the infusion preparation, two drying methods were used – stove and lyophi- lization, and overall the best results correspond to the infusions prepared with the lyophilized plant material. This material also had good overall scores in the sensory test (3.51 to 4.04 on a scale of 1 to 5) been the taste most appreciated by the panelists. CONCLUSIONS The bioactive compound concentration and the antioxidant activity of the coffee pulp suggest that waste can be used as a raw material for the preparation of functional foods, because the values found are similar or greater than those found in other drinks and fruits consumed commercially.