Plant Foods for Human Nutrition

, Volume 47, Issue 4, pp 361–367 | Cite as

Effect of blanching on the content of antinutritional factors in selected vegetables

  • T. C. Mosha
  • H. E. Gaga
  • R. D. Pace
  • H. S. Laswai
  • K. Mtebe
Article

Abstract

The effect of blanching on the antinutritional content was studied in cabbage, turnip, collard, sweetpotato and peanut leaves. All the vegetables contained various amounts of phytic acid, tannic acid and/or oxalic acid. Tannic acid was found in largest amounts ranging from 1266.00 mg/100 g in cabbage to 491.00 mg/100 g in sweetpotato. Phytic acid content ranged from 0.31 mg/100 g in sweetpotato to 3.97 mg/100 g in collard. Oxalic acid was in trace amounts in cabbage and turnip; but high concentrations were found in sweetpotato (469.67 mg/100 g) and peanut greens (407.00 mg/100 g). Levels of both tannic acid and phytic acid were significantly (p<0.05) reduced by conventional and microwave blanching methods while oxalic acid levels were not significantly (p<0.05) reduced in most of the treatments by either of the blanching methods. In general, blanching is recommended as an effective method for reducing the antinutritional factors in green vegetables, however, further investigation on the heating times for both conventional and microwave blanching methods has been suggested.

Key words

Antinutritional factors Conventional and microwave oven blanching Oxalic acid Phytic acid Tannic acid 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Anne F (1979) The role of wild foliage plants in the diet: A case study of Lushoto, Tanzania. Ecol Food Nutr 8(2): 87–93.Google Scholar
  2. 2.
    Schultink JW, West CE, Pepping F (1987) Beta-carotene content of Tanzanian foodstuffs. East Afric Med J 64(6): 368–371.Google Scholar
  3. 3.
    Camus MS, Laporte JC (1976) Effect of phytates on proteases. Ann Biol Anim Biochem Biophys 16: 719–729.Google Scholar
  4. 4.
    Connor HE (1977) The poisonous plants in New Zealand. Wellington, New Zealand: Government Printer, 143 pp.Google Scholar
  5. 5.
    Kelsay JL (1985) Effect of oxalic acid on bioavailability of calcium. In: C. Kies (ed), Nutritional bioavailability of calcium. Washington, DC: American Chemical Society.Google Scholar
  6. 6.
    AVRDC (1976) Annual report for 1975. Shanhua, Taiwan.Google Scholar
  7. 7.
    Evensen SK Standal BR (1984) Use of tropical vegetables to improve diets in the Pacific region. Honolulu: University of Hawaii, HITAHR Res Ser 28.Google Scholar
  8. 8.
    Halstred JA, Ronaghy HA, Abadi P, Haghshennass M, Amirhakemi GH, Barakat RM, Reinhold JG (1977) Zinc deficiency in man. Am J Med 53: 277–284.Google Scholar
  9. 9.
    Hoff-Jorgensen E, Anderson U, Nielsen G (1946) The effect of phytic acid on the absorption of calcium and phosphorus. Biochem J 40: 555–560.Google Scholar
  10. 10.
    Reinhold JG (1971) High content phytate of rural Iranian bread: A possible cause of zinc deficiency. Am J Clin Nutr 24: 1204–1206.PubMedGoogle Scholar
  11. 11.
    Halsam E (1966) Chemistry of vegetable tannins. New York: Academic Press.Google Scholar
  12. 12.
    Fairbairn JW (1989) The pharmacology of plant phenolics. New York: Academic Press.Google Scholar
  13. 13.
    Singleton VL, Kratzer FH (1969) Toxicity and related physiological activity of phenolic substances of plant origin. J Agric Food Chem 17: 497–501.Google Scholar
  14. 14.
    Ghazi A, Mtwali S, Atta MB (1989) Phenolic compounds in sweetpotato. Nahrung 33(2): 145–151.Google Scholar
  15. 15.
    Smith FJ (1977) How processing with microwave heat affects food qualities. Food Product Development 11: 60–65.Google Scholar
  16. 16.
    AOAC (1990) Official methods of analysis Washington, DC: Association of Official Analytical Chemists.Google Scholar
  17. 17.
    Steel RGD, Torrie JH (1980) The principles and procedures of statistics. New York: McGraw Hill.Google Scholar
  18. 18.
    Heaney RP, Weaver CM, Hinders SM, Martin B, Packard PJ (1993) Absorbability of calcium fromBrassica vegetables: Broccoli, Bok choy and Kale. J Food Sci 58(6): 1378–1380.Google Scholar
  19. 19.
    Hazell T (1988) Relating food composition data to iron availability from plant foods. Eur J Clin Nutr 42: 509–517.PubMedGoogle Scholar
  20. 20.
    Hazell T, Johnson IT (1987) Effect of food processing and fruit juices on in vitro estimated iron availability from cereals, vegetables and fruits. J Sci Food Agric 38: 7382.Google Scholar
  21. 21.
    Scholfield DJ, Rehall KM, Kelsay JL, Prather ES, Clark WM, Raiser S, Canary JJ (1990) The effect of natural dietary fiber from fruit and vegetable with oxalate from spinach on plasma minerals, lipids and other metabolites in men. Nutr Res 10: 367–378.Google Scholar
  22. 22.
    Hallberg, L, Rossander L, Skanberg AB (1987) Phytates and the inhibitory effect of bran on iron absorption in man. Am J Clin Nutr 45: 988–996.PubMedGoogle Scholar
  23. 23.
    Liebman M, Doane L (1989) Calcium and zinc balances during consumption of high and low oxalate-containing vegetables. Nutr Res 9: 947–955.Google Scholar
  24. 24.
    Hurrell RF, Juillert MA, Reddy MB, Lynch SR, Dassenko SA, Cook JD (1992) Soy protein, phytate and iron absorption in humans. Am J Clin Nutr 56: 573–578.PubMedGoogle Scholar
  25. 25.
    Baldwin DR, Anantheswaran RC, Sastry SK, Beelman RD (1986) Effect of microwave blanching on the yield and quality of canned mushrooms. J Food Sci 51(4): 965–966.Google Scholar
  26. 26.
    Chang R, Schwimmer D, Burr HK (1977) Phytate: Removal from whole dry beans by enzymatic hydrolysis and diffusion. J Food Sci 42: 1098–1101.Google Scholar

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • T. C. Mosha
    • 1
  • H. E. Gaga
    • 2
  • R. D. Pace
    • 3
  • H. S. Laswai
    • 1
  • K. Mtebe
    • 1
  1. 1.Department of Food Science and NutritionSokoine University of AgricultureMorogoroTanzania
  2. 2.Malawi Bureau of StandardsBlantyreMalawi
  3. 3.Department of Home EconomicsTuskegee UniversityTuskegeeUSA

Personalised recommendations