Method for Estimation of Tannin in Grain Sorghum¹

Abstract The acidified vanillin method of tannin analysis, widely used for forage crops, was modified to permit rapid estimation of relative tannin content of grain sorghum [ Sorghum bicolor (L.) Moench]. The method involves overnight extraction of ground grain with methanol at room temperature. An aliquot of the extract is added to a solution of vanillin and hydrochloric acid and the resultant color is read on a colorimeter at 500‐525 mµ The reagent is specific for astringent compounds in plants and the results were highly correlated with digestibility.