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Sunira Moses From Corn

Corn is a staple food in many parts of the world. Corn has been cultivated for almost 9000 years, originally domesticated in the Southern Lowlands of Mexico.

Composition and nutrients Link to the Composition and nutrients heading

  • Pericarp (Bran): outermost layer of the corn kernel

    • Rich in fiber, particularly insoluble fiber.

  • Endosperm: the food source for the embryo, makes up majority of kernel

    • Primarily composed of starch and protein.

  • Germ: the embryo of the corn kernel

    • Rich in healthy fats, vitamins (particularly vitamin E), minerals, and antioxidants.

    • When milled, the germ is often separated from the rest of the kernel due to its high fat content, which reduce shelf life.

Anti-Nutrients Link to the Anti-Nutrients heading

The bioavailability of nutrients in corn is limited due to the presence of the following anti-nutrients:

  • Phytic Acid (Phytates):

    • 0.89-1.21% by weight, highest concentration in the germ.
    • Forms insoluble complexes with minerals such as iron, zinc, magnesium, and calcium, reducing their absorption.
    • Heat-stable and resistant to digestive enzymes, but reduced by nixtamalization.

  • Saponins:

    • 0.01-0.1% by weight.
    • Form insoluble complexes with nutrients such as vitamins and minerals, particularly iron and zinc, reducing their absorption.
    • Heat-stable and resistant to digestive enzymes.

  • Oxalates:

    • 0.02-0.1% by weight.
    • Form insoluble complexes with minerals like calcium and magnesium, reducing their absorption.
    • Relatively heat-stable, but reduced by nixtamalization.

Nixtamalization Link to the Nixtamalization heading

Nixtamalization, the process of soaking and boiling corn in a heated alkaline solution (1-5% concentrate), typically lime or wood ash, for 30-90 minutes then steeping in the solution for 3-6 hours. This practice is ancient in South America, and is typically done before milling but it is possible to nixtamalize corn after its been milled. The process typically involves relatively vigorous stirring which often removes the softened germ and pericarp. This significantly enhances its nutritional profile:

  • Protein Quality: Increases the availability of essential amino acids.
  • Vitamin and Mineral Bioavailability: Particularly increases niacin (vitamin B3) and calcium, making these nutrients more absorbable.
  • Phytic Acid Reduction: Lowers levels of phytic acid, increasing the bioavailability of iron and other minerals.

During Nixtamalization Link to the During Nixtamalization heading

  • Phylates are reduced by 25% - 45%.
  • Saponins are reduced by up to 22%.
  • Essential amino acids lysine and tryptophan are made more bioavailable.
  • Niacin is made more bioavailable.
  • Calcium is added from the solution.
  • Zinc and iron increase.
  • The starch in the endosperm undergoes gelatinization, making it more easily digestible.
  • Some of the nutrients in the germ, such as the healthy fats (including essential fatty acids like linoleic acid) are lost.
  • The pericarp might be lost.

Usage Link to the Usage heading

Because nixtamalization effectively turns corn into a goop, it is typically milled and then used as dough or dried and becomes into cornmeal. Nixtalamalized cornmeal often has a deeper yellow color.

Resources Link to the Resources heading

  • Study on reduction of phtyic acid and increase of nutrients
  • Güçlü-Üstündağ, Ö., & Mazza, G. (2007). Saponins: properties, applications and processing. Critical Reviews in Food Science and Nutrition, 47(3), 231-258.
  • Lásztity, R. (1984). The Chemistry of Cereal Proteins (1st ed.). CRC Press.
  • Miyake, K., Tanaka, T., & McNeil, P. L. (2007). Lectin-based food poisoning: a new mechanism of protein toxicity. PloS one, 2(8), e687.
  • Pisulewska, E., & Pisulewski, P. M. (2000). Trypsin inhibitor activity of legume seeds (peas, chickling vetch, lentils, and soya beans) as affected by the technique of harvest. Animal Feed Science and Technology, 86(3-4), 261-265.
  • Ruan, Q. Y., Zheng, X. Q., Chen, B. L., Xiao, Y., Peng, X. X., Leung, D. W., & Liu, E. E. (2013). Determination of total oxalate contents of a great variety of foods commonly available in Southern China using an oxalate oxidase prepared from wheat bran. Journal of Food Composition and Analysis, 32(1), 6-11.
  • Schlemmer, U., Frølich, W., Prieto, R. M., & Grases, F. (2009). Phytate in foods and significance for humans: food sources, intake, processing, bioavailability, protective role and analysis. Molecular Nutrition & Food Research, 53(S2), S330-S375.
  • Serna-Saldivar, S. O. (2010). Cereal grains: properties, processing, and nutritional attributes. CRC press.
  • Shi, J., Wang, H., Wu, Y., Hazebroek, J., Meeley, R. B., & Ertl, D. S. (2003). The maize low-phytic acid mutant lpa2 is caused by mutation in an inositol phosphate kinase gene. Plant Physiology, 131(2), 507-515.