Antioxidant activity of crude tannins of canola and rapeseed hulls

  • R. Amarowicz
  • M. NaczkEmail author
  • F. Shahidi


The antioxidant activity of crude tannins of canola and rapeseed hulls was evaluated by β-carotene-linoleate, α,α-diphenyl-β-picrylhydrazyl (DPPH) radical, and reducing power assays. Crude tannins were extracted from three samples of Cyclone canola (high-tannin) hulls and Kolner, Ligaret, and Leo Polish rapeseed (low-tannin) hulls with 70% (vol/vol) acetone. The total phenolic content in crude tannin extracts ranged between 128 and 296 mg of sinapic acid equivalents per 1 g of extract. The ultraviolet spectra of methanolic solution of canola extracts showed two absorption maxima (282 and 309 nm), whereas those of rapeseed extracts exhibited a single maximum (326 nm). Crude tannins isolated from canola hulls exerted significantly (P<0.025) greater antioxidant activity than those from rapeseed in all three assays. The scavenging effect of all crude tannins, at a dose of 1 mg, on the DPPH radical ranged from 35.2 to 50.5%. The reducing power of Cyclone canola hull extracts on potassium ferricyanide was significantly (P≤0.0025) greater than that of rapeseed hull extracts, and the observed data correlated well (r=0.966; P=0.002) with the total content of phenolics present.

Key Words

Antioxidative properties canola condensed tannins hulls rapeseed reducing power scavenging effects 


  1. 1.
    Sherwin, E.R., Antioxidants, in Food Additives, edited by L.R. Branen, Marcel Dekker, New York, 1990, pp. 139–193.Google Scholar
  2. 2.
    Ito, N., M. Hirose, S. Fukishima, H. Tsuda, T. Shirai, and M. Tatematsu, Studies on Antioxidants: Their Anticarcinogenic and Modifying Effects on Chemical Carcinogenesis, Food Chem. Toxicol. 24:1099–1102 (1986).CrossRefGoogle Scholar
  3. 3.
    Pratt, D.E., and B.J.F. Hudson, Natural Antioxidants not Exploited Commercially, in Food Antioxidants, edited by B.J.F. Hudson, Elsevier, Amsterdam, 1990, pp. 171–192.Google Scholar
  4. 4.
    Shahidi, F., J.K. Daun, and D.R. DeClerq, Glucosinolates in Brassica Oilseeds: Processing Effects and Extraction, in Antinutrients and Phytochemicals in Food, edited by F. Shahidi, American Chemical Society, Washington, DC, 1997, pp. 157–170.Google Scholar
  5. 5.
    Naczk, M., R. Amarowicz, D. Pink, and F. Shahidi, Insoluble Condensed Tannins of Canola and Rapeseed Hulls, J. Agric. Food Chem. 48:1758–1762 (2000).CrossRefGoogle Scholar
  6. 6.
    Naczk, M., R. Amarowicz, A. Sullivan, and F. Shahidi, Current Research Developments on Polyphenols of Rapeseed/Canola: A Review, Food Chem. 62:489–502 (1998).CrossRefGoogle Scholar
  7. 7.
    Naczk, M., T. Nichols, D. Pink, and F. Sosulski, Condensed Tannins in Canola Hulls, J. Agric. Food Chem. 42:2196–2200 (1994).CrossRefGoogle Scholar
  8. 8.
    Nowak, H., K. Kujawa, R. Zadernowski, B. Roczniak, and H. Kozlowska, Antioxidative and Bactericidal Properties of Phenolic Compounds in Rapeseed, Fett Wiss. Technol. 94:149–152 (1994).CrossRefGoogle Scholar
  9. 9.
    Amarowicz, R., J. Fornal, and M. Karamac, Effect of Seed Moisture on Phenolic Acids in Rapeseed Cake, Grasas Aceites 46:354–356 (1995).Google Scholar
  10. 10.
    Amarowicz, R., A. Troszynska, M. Karamac, and H. Kozlowska, Antioxidative Properties of Legume Extracts, in Agri-Food Quality. An Interdisciplinary Approach, edited by G.R. Fenwick, C. Hedley, and S. Khokhar, The Royal Society of Chemistry, Cambridge, 1996, pp. 376–379.Google Scholar
  11. 11.
    Wanasundara, U., and F. Shahidi, Canola Extracts Alternative Natural Antioxidants for Canola Oil, J. Am. Oil Chem. 71:817–822 (1994).CrossRefGoogle Scholar
  12. 12.
    Wanasundara, U., R. Amarowicz, and F. Shahidi, Isolation and Identification of an Antioxidative Component in Canola Meal, J. Agric. Food Chem. 42:1285–1290 (1994).CrossRefGoogle Scholar
  13. 13.
    Sosulski, F., and R. Zadernowski, Fractionation of Rapeseed Meal into Flour and Hull Component, J. Am. Oil Chem. Soc. 58:96–98 (1981).CrossRefGoogle Scholar
  14. 14.
    Swain, T., and W.E. Hillis, The Phenolic Constituents of Prunus domesticus (L.). The Quantitative Analysis of Phenolic Constituents, J. Sci. Food Agric. 10:63–68 (1959).CrossRefGoogle Scholar
  15. 15.
    Miller, H.E., A Simplified Method for the Evaluation of Antioxidants, J. Am. Oil Chem. Soc. 48:91 (1971).Google Scholar
  16. 16.
    Hatano, T., H. Kagawa, T. Yasuhara, and T. Okuda, Two New Flavonoids and Other Constituents in Licorice Root: Their Relative Astringency and Radical Scavenging Effects, Chem. Pharm. Bull. 36:2090–2097 (1998).Google Scholar
  17. 17.
    Oyaizu, M., Studies on Products of Browning Reaction: Antioxidative Activities of Products of Browning Reaction Prepared from Glucosamine, Jpn. J. Nutr. 44:307–315 (1986).Google Scholar
  18. 18.
    Montgomery, D.C., Design and Analysis of Experiments, John Wiley & Sons, Inc., 4th edn., New York, 1997, pp. 63–120.Google Scholar
  19. 19.
    Scalbert, A., Quantitative Methods for the Estimation of Tannins in Plant Tissues, in Plant Polyphenols: Synthesis, Properties, Significance, edited by R.W. Hemingway and P. Laks, Plenum Press, New York, 1992, pp. 259–282.Google Scholar
  20. 20.
    Strumeyer, D.H., and M.J. Malin, Condensed Tannins in Grain Sorghum: Isolation, Fractionation, and Characterization, J. Agric. Food Chem. 23:909–914 (1975).CrossRefGoogle Scholar
  21. 21.
    Naczk, M., J. Wanasundara, and F. Shahidi, Facile Spectroscopic Quantification Method Sinapic Acid in Hexane-extracted and Methanol-Ammonia-Treated Mustard and Rapeseed Meals, —Ibid. 40:444–448 (1992).CrossRefGoogle Scholar
  22. 22.
    Mabry, T.J., K.R. Markham, and M.B. Thomas, The Systematic Identification of Flavonoids, Springer-Verlag, New York, 1970, pp. 35–61.Google Scholar
  23. 23.
    Rice-Evans, C.A., N.J. Miller, and G. Paganga, Structure-Antioxidant Activity Relationships of Flavonoids and Phenolic Acids, Free Radical Biol. Med. 20:933–956 (1996).CrossRefGoogle Scholar
  24. 24.
    Cuvelier, M.E., H. Richard, and C. Berset, Comparison of the Antioxidative Activity of Some Acid-Phenols: Structure-Activity Relationship, Biosci. Biotechnol. Biochem. 56:324–325 (1992).CrossRefGoogle Scholar
  25. 25.
    Ariga, T., and M. Hamano, Radical Scavenging Action and Its Mode in Procyanidins B-1 and B-3 from Azuki Beans to Peroxyl Radicals, Agric. Biol. Chem. 54:2499–2504 (1990).Google Scholar
  26. 26.
    Brand-Williams, W., M.E. Cuvelier, and C. Berset, Use of Free Radical Method to Evaluate Antioxidant Activity, Food Sci. Technol. 28:25–30 (1995).Google Scholar
  27. 27.
    Bondet, V., W. Brand-Williams, and C. Berset, Kinetics and Mechanisms of Antioxidant Activity Using the DPPH Free Radical Method, —Ibid. 30:609–615 (1997).Google Scholar
  28. 28.
    Shahidi, F., and M. Naczk, Food Phenolics: Sources, Chemistry, Effects, Applications, Technomic Publishing Co., Inc., Lancaster, 1995, pp. 235–280.Google Scholar
  29. 29.
    Yen, G.-C., and H.-Y. Chen, Antioxidant Activity of Various Tea Extracts in Relation to Their Antimutagenicity, J. Agric. Food Chem 43:27–37 (1995).CrossRefGoogle Scholar
  30. 30.
    Amarowicz, R., B. Raab, and M. Karamac, Antioxidative Activity of Ethanolic Extracts of Evening Primrose, Nahrung 40: 376–379 (1999).Google Scholar

Copyright information

© AOCS Press 2000

Authors and Affiliations

  1. 1.Department of BiochemistryMemorial University of NewfoundlandSt. John'sCanada
  2. 2.Department of Human NutritionSt. Francis Xavier UniversityAntigonishCanada

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