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Sorghum pp 109-120 | Cite as

Tannin Analysis in Sorghum Grains

  • Linda DykesEmail author
Protocol
Part of the Methods in Molecular Biology book series (MIMB, volume 1931)

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. In this chapter, three methods of tannin analysis are described: (1) Chlorox bleach test; (2) modified vanillin-HCl assay; and (3) normal-phase high-performance liquid chromatography (NP-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.

Key words

Sorghum Condensed tannins Chlorox bleach test Vanillin-HCl assay Normal-phase HPLC Fluorescence detection 

Notes

Acknowledgment

Special thanks to Dr. Tom Herald, USDA-ARS, Center for Grain and Animal Health Research, Manhattan, KS, for providing the sorghum samples for the Chlorox bleach test procedure.

Disclaimer: Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.

References

  1. 1.
    Awika JM, Dykes L, Gu L, Rooney LW, Prior RL (2003) Processing of sorghum (Sorghum bicolor) and sorghum products alters procyanidin oligomer and polymer distribution and content. J Agric Food Chem 51:5516–5521CrossRefGoogle Scholar
  2. 2.
    Awika JM, McDonough CM, Rooney LW (2005) Decorticating sorghum to concentrate healthy phytochemicals. J Agric Food Chem 53:6230–6234CrossRefGoogle Scholar
  3. 3.
    Dykes L, Rooney LW, Waniska RD, Rooney WL (2005) Phenolic compounds and antioxidant activity of sorghum grains of varying genotypes. J Agric Food Chem 53:6813–6818CrossRefGoogle Scholar
  4. 4.
    Dykes L, Seitz L, Rooney WL, Rooney LW (2009) Flavonoid composition of red sorghum genotypes. Food Chem 116:313–317CrossRefGoogle Scholar
  5. 5.
    Dykes L, Peterson GC, Rooney WL, Rooney LW (2011) Flavonoid composition of lemon-yellow sorghum genotypes. Food Chem 128:173–179CrossRefGoogle Scholar
  6. 6.
    Dykes L, Rooney WL, Rooney LW (2013) Evaluation of phenolics and antioxidant activity of black sorghum hybrids. J Cereal Sci 58:278–283CrossRefGoogle Scholar
  7. 7.
    Hahn DH, Faubion JM, Rooney LW (1983) Sorghum phenolic acids, their high performance liquid chromatography separation and their relation to fungal resistance. Cereal Chem 60:255–259Google Scholar
  8. 8.
    Dykes L, Rooney LW (2006) Sorghum and millet phenols and antioxidants. J Cereal Sci 44:236–251CrossRefGoogle Scholar
  9. 9.
    Rooney LW, Miller FR (1982) Variation in the structure and kernel characteristics of sorghum. In: Mertin JV (ed) Proceedings of the International Symposium on Sorghum Grain Quality. International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), 28–31 Oct 1982, Patancheru, APGoogle Scholar
  10. 10.
    Price ML, Van Scoyoc S, Butler LG (1978) A critical evaluation of the vanillin reaction as an assay for tannin in sorghum grain. J Agric Food Chem 26:1214–1218CrossRefGoogle Scholar
  11. 11.
    Boren B, Waniska RD (1992) Sorghum seed color as an indicator of tannin content. J Appl Poult Res 1:117–121CrossRefGoogle Scholar
  12. 12.
    International Association for Cereal Science and Technology (2017) Standard Method 177: Detection of tannin sorghum grain by the bleach test. Approved 2012. International Association for Cereal Science and Technology, ViennaGoogle Scholar
  13. 13.
    Grain Inspection, Packers and Stockyards Administration (2013) Sorghum. In: Grain inspection handbook II. https://www.gipsa.usda.gov/fgis/gradingprocedures.aspx. Accessed Oct 2017
  14. 14.
    Taylor JRN, Taylor J (2008) Five simple methods for the determination of sorghum grain end-use quality (with adaptations for those without laboratory facilities). INTSORMIL Scientific Publications 17. USAID, INTSORMIL, University of Pretoria, Pretoria, South AfricaGoogle Scholar
  15. 15.
    Waniska RD, Hugo LF, Rooney LW (1992) Practical methods to determine the presence of tannins in sorghum. J Appl Poult Res 1:122–128CrossRefGoogle Scholar
  16. 16.
    Schoffield P, Mbugua DM, Pell AN (2001) Analysis of condensed tannins: a review. Anim Feed Sci Technol 91:21–40CrossRefGoogle Scholar
  17. 17.
    Butler LG (1989) Sorghum polyphenols. In: Cheeke PR (ed) Toxicants of plant origin, Phenolics, vol IV. CRC Press, Inc, Boca Raton, FLGoogle Scholar
  18. 18.
    Hagerman AE, Butler LG (1980) Condensed tannin purification and characterization of tannin-associated proteins. J Agric Food Chem 28:947–952CrossRefGoogle Scholar
  19. 19.
    Hahn DH, Rooney LW (1986) Effect of genotype on tannins and phenols of sorghum. Cereal Chem 63:4–8Google Scholar
  20. 20.
    Adamson GE, Lazarus SA, Mitchell AE, Prior RL, Cao G, Jacobs PH, Kremers BG, Hammerstone JF, Rucker RB, Ritter KA, Schmitz HH (1999) HPLC method for the quantification of proycanidins in cocoa and chocolate samples and correlation to total antioxidant capacity. J Agric Food Chem 47:4184–4188CrossRefGoogle Scholar
  21. 21.
    Gu L, Kelm M, Hammerstonne JF, Beecher G, Cunningham D, Vannozzi S, Prior RL (2002) Fractionation of polymeric procyanidins from lowbush blueberry and quantification of procyanidins in selected foods with an optimized normal-phase HPLC-MS fluorescent detection method. J Agric Food Chem 50:4852–4860CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Cereal Crops Research Unit, Red River Valley Agricultural Research CenterUSDA-ARSFargoUSA

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