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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
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.
Schultink JW, West CE, Pepping F (1987) Beta-carotene content of Tanzanian foodstuffs. East Afric Med J 64(6): 368–371.
Camus MS, Laporte JC (1976) Effect of phytates on proteases. Ann Biol Anim Biochem Biophys 16: 719–729.
Connor HE (1977) The poisonous plants in New Zealand. Wellington, New Zealand: Government Printer, 143 pp.
Kelsay JL (1985) Effect of oxalic acid on bioavailability of calcium. In: C. Kies (ed), Nutritional bioavailability of calcium. Washington, DC: American Chemical Society.
AVRDC (1976) Annual report for 1975. Shanhua, Taiwan.
Evensen SK Standal BR (1984) Use of tropical vegetables to improve diets in the Pacific region. Honolulu: University of Hawaii, HITAHR Res Ser 28.
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.
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.
Reinhold JG (1971) High content phytate of rural Iranian bread: A possible cause of zinc deficiency. Am J Clin Nutr 24: 1204–1206.
Halsam E (1966) Chemistry of vegetable tannins. New York: Academic Press.
Fairbairn JW (1989) The pharmacology of plant phenolics. New York: Academic Press.
Singleton VL, Kratzer FH (1969) Toxicity and related physiological activity of phenolic substances of plant origin. J Agric Food Chem 17: 497–501.
Ghazi A, Mtwali S, Atta MB (1989) Phenolic compounds in sweetpotato. Nahrung 33(2): 145–151.
Smith FJ (1977) How processing with microwave heat affects food qualities. Food Product Development 11: 60–65.
AOAC (1990) Official methods of analysis Washington, DC: Association of Official Analytical Chemists.
Steel RGD, Torrie JH (1980) The principles and procedures of statistics. New York: McGraw Hill.
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.
Hazell T (1988) Relating food composition data to iron availability from plant foods. Eur J Clin Nutr 42: 509–517.
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.
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.
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.
Liebman M, Doane L (1989) Calcium and zinc balances during consumption of high and low oxalate-containing vegetables. Nutr Res 9: 947–955.
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.
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.
Chang R, Schwimmer D, Burr HK (1977) Phytate: Removal from whole dry beans by enzymatic hydrolysis and diffusion. J Food Sci 42: 1098–1101.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Mosha, T.C., Gaga, H.E., Pace, R.D. et al. Effect of blanching on the content of antinutritional factors in selected vegetables. Plant Food Hum Nutr 47, 361–367 (1995). https://doi.org/10.1007/BF01088275
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01088275