Effect of processing methods on some micronutrients, anti-nutrients and toxic substances in Vernonia amygdalina leaves


  • Musa, A., Department of Biochemistry, Federal University of Technology, Minna Author https://orcid.org/0000-0001-6461-2362
  • Akanya, F. H Department of Biochemistry, Federal University of Technology, Minna Author
  • Oladiran, J. A., Department of Crop Production, Federal University of Technology, Minna Author
  • Ezenwa, M. I. S. Department of Soil Science, Federal University of Technology, Minna Author
  • Ogbadoyi, E. O. Department of Biochemistry, Federal University of Technology, Minna, Nigeria Author


Studies were conducted to investigate the effect of processing methods on antinutrients (soluble and total oxalates), toxic substances (cyanide and nitrate) and some micronutrients, vitamin C, β-carotene (vitamin A precursor) and mineral elements (Fe, Cu, Mg, Na and K) in Vernonia amygdalina. The processing methods used were boiling and sun drying. Results obtained showed that the nitrate content (1347.22 mg/kg) in the fresh vegetable is within the tolerable level and can be well tolerated in our meal. The cyanide level (199.11 mg/kg) is close to the maximum tolerable level of 200 mg/kg fresh weight. The levels of soluble and total oxalates in the fresh samples (2.80 g/kg and 4.76 g/kg respectively), were high enough to induce toxicity in human. All processing methods adopted significantly (p < 0.05) reduced the anti-nutrients and toxic substances in the vegetable. Boiling methods reduced the anti-nutrients and toxic substances significantly (p < 0.05) more than sun drying. The anti-nutrients and toxic substances decreased with boiling time. The processing methods also decreased vitamin C content significantly (p < 0.05) in the vegetable. Boiling methods retained more of the vitamin compared to sun drying. β-carotene levels increased in boiled vegetable, while its content was reduced in sundried sample. However, boiling exceeding 5 minutes led to reduction of the provitamin A content. Mineral elements also decreased with boiling. However, sun drying had no significant effect on the mineral contents of the vegetable. In conclusion, moderate boiling significantly reduces the levels of antinutrients and toxic substances ...


Download data is not yet available.


Abakr, A. and Ragaa, A. (1996). Trials to reduce nitrate and oxalate content in some leafy vegetables; Interactive effect of manipulating of the soil nutrient supply, different blanching media and preservation methods followed by cooking process. J. Sci. Food Agric., 97: 169- 178.

Adanlawo, I. G. and Ajibade, V. A. (2006). Nutritive value of the two varieties of roselle (Hibiscus sabdariffa) Calyces soaked with wood ash. Pak. J. Nutr., 5 (6): 555-557.

Addo. A. A. (1983). Ascorbic acids contents of food commonly consumed in the Northern States of Nigeria. Nig. Food J., 1(1): 129-133.

Aganga, A. A. and Tshwenyane. S. O. (2003). Feeding values and anti-nutritive factors of forage tree legumes. Pak. J. Nutr., 2(3): 170- 173.

Akanya, H. O. (2004). Retinol: The vitamin of life. Federal University of Technology, Minna. Inaugural Lecture Series No. 5. Scan Prints Nig. Ltd. p. 12.

Aliyu, H. M. and Morufu, A. I. (2006). Proximate analysis of some leafy vegetables (Roselle, jute and bitter leaf). Int J. Foods & Agric. Res., 3 (1): 194-198.

Ames, M. A., Moyer, T. P., Kavash, J. S., Moertel, C. G. and Rubin, J. (1981). Pharmacology of amygdalin (Laetrile) in cancer patients. Cancer Chemother. Pharmacol., 6: 51-57.

Anjana, S. U. and Muhammad, I. (2006). Nitrate accumulation in plants, factors affecting the process, and human health implications. A review. Agronomy for Sustainable Dev., 101: 1051-1060.

Anjana, S. U., Muhammed, I. and Abrol. Y. P. (2007). Are nitrate concentrations in leafy vegetables within safe limits? Curr. Sci., 92(3): 355-360.

Antia, B. S., Akpan, E. J., Okon, P. A. and Umoren, I. U. (2006). Nutritive and antinutritive evaluation of sweet potatoes (Ipomoea batatas) leaves. Pak. J. Nutr., 5(2): 166-168.

Aster-Damas, M. (1975). Change in nitrate, vitamin C, magnesium and iron contents of spinach. Annales Dela Nutr., 29: 239-244.

Augustine, J., Beck, G. B., Kalbfleish, G., Kagel, L. C. and Mathews, R. H. (1981). Variation in the vitamin and mineral contents of raw and cooked commercial Phaseolus valgaris classes. J. Food Sci. 46: 1701-1706.

Chweya, J. A. and Nameus, A. M. (1997). Cats whiskers (Cleome gynandra L). promoting the conservation and use of underutilized and neglected crops. II. Institute of plant genetics and crop plant research. Gatersleben/International plant Genetic Resources Institute, Rome, Italy. p. 18 - 21.

Ejoh, A. R., Tanya, A. N., Djuikwo, N. A. and Mbofung, C. M. (2005). Effect of processing and preservation methods on vitamin C and total carotenoid levels of some Vernonia (bitter leaf) species. Afr. J. Food Agric. Nutr. & Dev., 5 (2): 105-117.

Eleri, T. and Hughes, R. E. (1983). Foliar ascorbic acid in some Angiosperms. Phytochem., 2(11): 2493.

Elllenhorn, M. J. and Barcelonx, D. G. (1988). Dical toxicology; Diagnosis and treatment of human poisoning. New York:Elsevier Science Publishing Co. p. 204-207.

Everist, S. L. (1981). Poisonous plants of Australia. Revised edn. Sydney: Angus and Robertson. p. 5-11.

Ezeonu, F. C., Musa, A., Stanly, C. D. and Oswald, C. E. (2002). Iron and zinc status in soils, water and stable food cultivars in Itakpe, Kogi State of Nigeria. The Environmentalist, 22: 237-240.

Fafunso, M. and Bassir, O. (1976). Variation in the loss of vitamin in leafy vegetables. Food Chem. 2: 51-55.

George, D. P. R. (1999). Newlife style: Enjoy it. Editorial Safeliz. Spain. p. 39-100.

Hambidge, K. M., Cassey, C. E. and Krebs, N. F. (1987). Zinc. In: trace element in human and animal nutrition. Mertz, W. (ed). Orlando: Academic Press. p. 1-138.

Ikediobi, C. O., Onyia, G. O. C. and Eluwah, C. E. (1980). A rapid and inexpensive non-enzymatic assay for total cyanide in cassava (Manihot esculenta Crantz.) and cassava product. Agric. Biol. Chem. 44: 2803-2808.

Keshinro, O. O. and Ketiku, A. O. (1983). Effect of traditional cooking on ascorbic acid content of some Nigeria leafy vegetables. Food Chem., 3: 303-309.

Khalid, I., Alam, K. and MuzaffarAli, M. K. K. (2004). Biological significance of ascorbic acid (vitamin C) in human health–A review. Pak. J. Nutr., 3(1): 5-13.

Magmus Pyke, O. B. E. (1979). Success in nutrition. London:John Murray Ltd,. p. 100-102. 21

Mathook, F. M. and Imungi, J. K. (1994). Ascorbic acid changes in three indigenous Kenyan leafy vegetable during traditional cooking. Ecol. Food & Nutr., 32:239-245.

McDonald, J. K., Caflin, N. A., Sommano. S. and Cocksedge, R. (2006). The effect of post harvest handling on selected native food plant: A report for the rural Industries Research and Development Corporation.

Nakata, P. A. (2003). Advances in our understanding of calcium oxalate crystal formation and function in plants. Plant Sci., 164: 901-909.

Oboh, .G. (2005). Effect of some post harvest treatment on the nutritional properties of Cnidoscolus acontifolus leaf. Pak. J. Nutr., 4(4): 226-230.

Ogbadoyi, E. O., Makun, A. H., Bamigbade, O. R., Oyewale, O. A. and Oladiran, J. A. (2006). The effect of processing and preservation methods on the oxalate levels of some Nigeria leafy vegetables. Biokemistri. 18(2):121-125.

Oguchi, Y., Weerakkody, W. A. P., Tanaka, A., Nakazawa, S. and Ando, T. (1996). Varietal differences of quality-related compounds in leaves and petioles of spinach grown at two locations. Bull. Horishima Prefectural Agric. Res. Center. 64:1-9.

Ojiako, O. A. and Igwe, C. U. (2008). The nutritive, anti-nutritive and hepatotoxic properties of Trichosanthes anguina (Snake tomato) fruits from Nigeria. Pak. J. Nutr., 7(1):85-89.

Oke, L. O. (1966). Composition of some Nigeria leafy vegetables. J. Am. Dietetic Ass., 53:130-132.

Okon, E. U. and Akpanyung, E. O. (2005). Nutrients and antinutrients in selected brands of malts drink products in Nigeria. Pak. J. Nutr., 4(5):352-355.

Olaofe, O. (1992). Vitamin C content of Nigerian food-stuffs. Nig. J. Nutr. Sci., 13(1&2):1-7.

Oshodi, A. A. (1992). Comparison of proteins, minerals and vitamin C content of some dried leafy vegetables. Pak. J. Sci. & Ind. Res., 35:267-269.

Oyenuga, V. A. and Fetuga, B. C. (1975). Dietary importance of fruits and vegetables. A paper presented at the first national seminal on fruit and vegetables. Natl. Horticultural Res. Inst. p. 19-23.

Prohp, T. P., Ihimire, I. G., Madusha, A. O., Okpala, H. O, Erebor, J. O. and Oyinbo. C. A. (2006). Some antinutritional and mineral contents of extra-cotyledonous deposit of pride of barbados (Caesalpina pulcherrima). Pak. J. Nutr., 5(2): 114-116.

Richard, D. W. (1991). Cooperative Extension Service: Cooperative Extension Work Acts: May 8 and June 30, 1914, as amended, Kansas State University, County Extension Councils. Extension Districts and U.S. Department of Agriculture Cooperative.

Rickman, J. C., Bruhn, M. C. and Barret, D. M. (2007). Nutritional comparison of fresh, frozen and canned fruits and vegetables II. Vitamin A and caroteniods, Vitamin E, minerals and fiber. J. Sci. Food & Agric., 88:1185-1196.

Ryan, M. F. (1991). The role of magnesium in clinical biochemistry: an overview. Ann. Clin. Biochem., 28: 19.

Sandberg, A. S., Hulthen, R. and Turk. M. (1996). Dietary Aspergillus niger phatase increases iron absorption in human. J. Nutr. 126:476-480.

Schippers, R. R. (2000). African indigenous vegetables: An overview of the cultivated species. England: University Greenwwish. p. 193–205.

Shahnaz. A., Khan, K. M., Munirm, A. and Muhammed, S. (2003). Effect of peeling and cooking on nutrient in vegetables. Pak. J. Nutr., 2(3):189-191.

Shingeru, M., Noriko, Y. and Keerthis, S. G. (2003). Simple capillary electrophoretic determination of soluble oxalate and nitrate in forage grasses. J. Vet. Diagn. Invest., 15:480-483.

Sjoberg, A. M. K. and Alanko, T. A. (1994). Spectrophotometric determination of nitrate in baby food: Collaborative study. J. AOAC Int., 77(2):425-430.

Tietz, N. W., Carl, A. B. and Edward, R. A. (1994). Tietz Textbook of Clinical Chemistry. 2nd edn. London: W. B. Saunders Company. p. 1184-1235.

USDA. (1998). U. S. Department of Agricultural Research Service. Nutrient Data Laboratory USDA Nutrient Database for Standard Reference. http://www.nal.usda.gov/fnic/food comp/Data/

Waclaw, M. and Stefan. S. (2004). Effect of culinary processes on the content of nitrates and nitrites in potatoes. Pak. J. Nutr., 3(6):357-361.

Wayne, A. P. and Dale, B. H. (1989). Understanding your health. 2nd edn. USA, St. Louis: Time Mirrow/Mosby College Publishing. p. 107.



How to Cite

Effect of processing methods on some micronutrients, anti-nutrients and toxic substances in Vernonia amygdalina leaves. (2011). Nigerian Journal of Biochemistry and Molecular Biology, 26(1), 10-22. https://www.nsbmb.org.ng/journals/index.php/njbmb/article/view/261