Location: Cereal Crops ResearchTitle: Tannin analysis in sorghum grains
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 10/1/2018
Publication Date: 1/1/2019
Citation: Dykes, L. 2019. Tannin analysis in sorghum grains. In: Zhao, Z.-Y., Dahlberg, J., editors. Sorghum: Methods and Protocols. New York, NY: Springer. p. 109-119.
Technical Abstract: Sorghum (Sorghum bicolor (L.) Moench) contains a wide variety of phenolic compounds and their levels and types depend on the genotype. Sorghums with a pigmented testa contain condensed tannins, which are concentrated in the pigmented testa of the grain. In this chapter, three methods of tannin analysis are described: (1) Chlorox bleach test; (2) modified vanillin-HCl assay; and (3) normal-phase HPLC with fluorescence detection. The Chlorox bleach test is a rapid and inexpensive method that identifies non-tannin and tannin sorghums. The modified vanillin-HCl assay is a colorimetric assay that provides relative tannin values among sorghum samples. The normal-phase HPLC with fluorescence detection separates and quantifies condensed tannins according to their degree of polymerization and confirms the presence or absence of tannins.