Springer Nature is making Coronavirus research free. View research | View latest news | Sign up for updates

Radial diffusion method for determining tannin in plant extracts

  • 1229 Accesses

  • 398 Citations


Tannin in plant extracts can be determined by reacting the tannin with a protein and quantitating the precipitated complex. In the new assay described here, a tannin-containing solution is placed in a well in a protein-containing agar slab. As the tannin diffuses into the gel and complexes with protein, a visible ring of precipitation develops. The area of the ring is proportional to the amount of tannin in the extract. The detection limit of the method is 0.025 mg tannic acid or condensed tannin and the precision is 6% (relative standard deviation). Tests with extracts of a variety of plants show that the new method gives results comparable to other precipitation methods and that the new method is superior for samples of unusual composition, such as aspen buds. The method has several advantages over other methods for determining tannin: The new method is very simple and requires neither complex reagents nor instruments. Components of the plant extract such as non-tannin phenolics or water-insoluble compounds do not interfere with the method. The assay is not subject to interference from the organic and aqueous solutions which are commonly used to extract tannin from plants.

This is a preview of subscription content, log in to check access.


  1. Asquith, T.N., andButler, L.G. 1985. Use of a dye-labeled protein as a spectrophotometric assay for protein precipitants such as tannin.J. Chem. Ecol. 11:1535–1544.

  2. Bate-Smith, E.C. 1973. Haemanalysis of Tannins. The concept of relative astringency.Phyto-chemistry 12:907–192.

  3. Bate-Smith, E.C. 1975. Phytochemistry of proanthocyanidins.Phytochemistry 14:1107–1113.

  4. Becker, W. 1969. Determination of antisera titres using the single radial immunodiffusion method. Immunochemistry 6:539–546.

  5. Fletcher, A.C., Porter, L.J., Haslam, E., andGupta, R.K. 1977. Plant proanthocyanidins. Part 3. Conformational and configurational studies of natural procyanidins.J. Chem. Soc. Perkin I 1977:1628–1637.

  6. Folin, O., andDenis, W. 1915. A colorimetric method for the determination of phenols (and phenol derivatives) in urine.J. Biol. Chem. 22:305–308.

  7. Hagerman, A.E., andButler, L.G. 1978. Protein precipitation method for the quantitative determination of tannins.J. Agric. Food Chem. 26:809–812.

  8. Hagerman, A.E., andButler, L.G. 1980a. Determination of protein in tannin-protein precipitates.J. Agric. Food Chem. 28:944–947.

  9. Hagerman, A.E., andButler, L.G. 1980b. Condensed tannin purification and characterization of tannin-associated proteins.J. Agric. Food Chem. 28:947–952.

  10. Hagerman, A.E., andButler, L.G. 1981. Specificity of the proanthocyanidin-protein interaction.J. Biol. Chem. 256:4494–4497.

  11. Hagerman, A.E., andKlucher, K. 1986. Tannin-protein interactions, pp. 67–76,In J. Harborne and E. Middleton (eds.). Flavonoids in Biology and Medicine: Biochemical, Pharmacological and Structure-Activity Relationships, Alan R. Liss, New York.

  12. Haslam, E. 1979. Vegetable tannins.Recent Adv. Phytochem. 12:475–523.

  13. Martin, J.S., andMartin, M.M. 1983. Tannin assays in ecological studies. Precipitation of ribulose-1,5-bisphosphate carboxylase/oxygenase by tannin acid, quebracho, and oak foliage extracts.J. Chem. Ecol. 9:285–294.

  14. Price, M.L., Van Scoyoc, S., andButler, L.G. 1978. A critical evaluation of the vanillin reaction as an assay for tannin in sorghum grain.J. Agric. Food Chem. 26:1214–1218.

  15. Swain, T. 1979. Tannins and lignins, pp. 657–682,In G.A. Rosenthal and D.H. Janzen (eds.). Herbivores: Their Interaction with Secondary Plant Metabolites. Academic Press, New York.

  16. Vaerman, J.P. 1981. Single radial immunodiffusion.Methods Enzymol. 73:291–305.

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Hagerman, A.E. Radial diffusion method for determining tannin in plant extracts. J Chem Ecol 13, 437–449 (1987).

Download citation

Key Words

  • Tannin
  • proanthocyanidin
  • protein precipitation
  • digestibility-reducing substances
  • phenolic analysis