[Extraction and quantification of polyphenols from coffee pulp]

The polyphenol content of coffee pulp extracts was determined using the Folin-Ciocalteau method. The use of polyvynilpirrolidone (PVP) was introduced in order to eliminate interferences. Condensed polyphenols in the extracts were determined by the method of acidified vanillin. Chlorogenic acid and catechin were used as standards for Folin-Ciocalteau and Vanillin methods, respectively, and a calibration curve was constructed for each solvent. The solvents used were methanol, methanol-water (50:50), ammonium hydroxide (3%) and calcium hydroxide (1%), using times of extraction of 10 minutes and 1 hour. No differences were found in the amount of polyphenols extracted by the different solvents at the two extraction times. After 10 minutes, the alkaline solvents NH4OH (3%) and Ca(OH)2 (1%), extracted more polyphenols than the other two solvents. Nevertheless, ammonium hydroxide (3%) was more efficient in extracting condensed polyphenols. The results herein presented suggest that treating coffee pulp with mild alkaline solvents may improve its nutritive value.