The quantification of condensed tannins in African savanna tree species

► Quebracho tannin overestimated condensed tannins by 0.7-8.3 times. ► Sorghum tannin underestimated condensed tannins by 0.3-0.8 times. ► Sorghum tannin was an appropriate external standard for Scutia myrtina. ► Tannin chemical characteristics may explain reactivity in the acid-butanol assay.