Extraction of condensed tannins from beach pea (Lathyrus maritimus L.) as affected by different solvents

Abstract

The condensed tannins of beach pea, green pea and grass pea were extracted using methanol or acetone at different concentrations with or without acidification. Among solvents tested, 70% acetone, containing 1% concentrated HCl, extracted a maximum amount of condensed tannins from beach pea, green pea and grass pea. Condensed tannins extracted were assayed using a 0.5% vanillin solution in methanol containing 4% HCl (v/v). Beach pea contained a higher amount of condensed tannins (11.6 g/100 g) than Indian grass pea (1.54 g/100 g), Canadian grass pea (109 mg/100 g) or green pea (72.0 mg/100 g). The fresh green seeds and pod shells of beach pea had lower amounts of tannins (7.19 and 9.13 g/100 g, respectively) than mature seeds and pod shells (11.7 and 2.05 g/100 g, respectively). Branches plus stems of beach pea contained the lowest amount of condensed tannins (0.95 g/100 g) as compared to all other parts of the plant.