Quantification of Tannins from Curupay Bark

ABSTRACT This study aimed to assess the influence of time and sodium sulfite concentration on tannin yield in Curupay bark and propose better extraction conditions. The extractions were performed using 100 g of dried bark and 1500 mL of water at 70 °C, with extraction times of 2, 3, and 4 h and amount of extractor salt at the concentrations of 0, 1, 2, 3, and 4%. The following parameters were evaluated: content of total solids, total yield of solids, Stiasny index, and gravimetric yield of condensed tannins and non-tannins. Results show that the higher the concentration of sodium sulfite, the higher the content and yield of solids, as well as the higher the extraction of non-tannin compounds. Three-hour extraction time at 3.0% sodium sulfite concentration was the best condition to extract tannins from Curupay bark, under which a condensed tannin yield of 20.46% was obtained.