Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/13/2002
Publication Date: 5/1/2005
Citation: Bryant, R.J., Dorsch, J.A., Peterson, K.L., Rutger, J.N., Raboy, V. 2005. Phosphorus and mineral concentration in whole grain and milled low phytic acid (lpa) 1-1 rice. Cereal Chemistry. 82(5):517-522. Interpretive Summary: Phytic acid, a phosphorus containing compound, is known to bind minerals such as iron, calcium, and zinc in slightly acidic conditions. Coupled with its characteristic of being indigestible, this compound, which is commonly found in grains such as rice, reduces the availability of minerals when consumed. A Kaybonnet low phytic acid (lpa1) mutant and its parent, Kaybonnet, were subjected to different degrees of milling. Each milled sample was examined for its phytic acid content. The total phytic acid concentration in the brown rice of lpa1 was 48.6% lower than that of the parent. Even though some phytic acid appears to be present in the endosperm, 64% of the phytic acid is removed at the 10% milling level. The development of the above low phytic acid rice line would be of significant nutritional concern to a large portion of the world's population where mineral deficiency is common.
Technical Abstract: Phytic acid [(myo)-inositol 1, 2, 3, 4, 5, 6-hexakisphosphate] is known to bind phosphorus and chelate minerals, such as iron, in slightly acidic conditions thus making them unavailable when consumed. Coupled with its characteristic of being poorly digested by humans and other non-ruminant animals, this compound is commonly found in cereal grains. Brown rice of Kabonnet low phytic acid (lpal) mutant and the parent, Kaybonnet, were milled to different degrees (0, 10, 12, 17, 20, 22 and 25%) and compared for their phytic acid content using anion-exchange high-performance liquid chromatography. The total phytic acid concentration in the unmilled (0%) brown rice of lpa1 (8.4 mg/g) was 49.4% lower than that of the parent (16.6 mg/g). At 10% milling, the phytic acid content decreased to 2.7 mg/g for lpa1 and 5.1 for the parent. At 12, 15, and 17% milling, the phytic acid concentrations for lpa1 were 1.9, 1.7, and 1.0 mg/g, respectively, whereas, ,concentrations for the parent were 3, 4, 2, 6, and 1.5 mg/g, respectively. Even at 25% milling there was still a small amount of phytic acid present, 0.3 mg/g for lpa1 and 0.5 for the parent. Although some phytic acid will remain in milled rice, since most rice is milled to between 8 and 12% on a paddy basis (10 to 15% brown rice basis), the amount in lpa1 will still be 47.1% less than that of the parent. Even though phytic acid appears to be present in the endosperm, 64% of it is removed in the 10% milling. The phytic acid content of thirteen varieties were also determined and found to be between 12.2 and 19.6 mg/g of the brown rice flour.