Tannins from mimosoid legumes of Texas and Mexico

The percentage of tannins in leaves, bark, wood, and immature fruits of several species of Acacia and related mimosoid legumes from the southwestern U.S. and Mexico, along with a few from Costa Rica and Argentina, was determined by a modified hide powder procedure and by precipitation with casein. The relative percentages of hydrolyzable and condensed tannins were determined by the iodate and the vanillin-HCl methods, respectively. Gallotannins of selected samples were also determined by the rhodanine method. Although the amount of total tannins was similar for the first two methods, values for condensed tannins by the vanillin-HCl method were frequently two to four times greater than the total tannin values.