Publication no. C-2003-1119-07R |  VIEW ARTICLE

Study of Calcium Ion Diffusion in Components of Maize Kernels During Traditional Nixtamalization Process.

J. L. Fernández-Muñoz (1), Isela Rojas-Molina (2,3), M. L. González-Dávalos (2,6), Myriam Leal (4,5), M. E. Valtierra (4,5), E. San Martín-Martinez (1), and M. E. Rodríguez (5,7). (1) Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, I.P.N, Unidad Querétaro, C.P. 76040, José Siurob 10, Col Alamedas, Querétaro, Qro, México. (2) Facultad de Ciencias Naturales, Licenciatura en Nutrición, Universidad Autónoma de Querétaro, Querétaro, Qro, México. (3) Facultad de Ciencias Químicas, Postgrado en Química, Universidad Nacional Autónoma de México, México. (4) Ganaderos Asociados de Querétaro, S. A. de C. V, Carretera libre Querétaro-Celaya, Km 6.5, Querétaro, Querétaro, Qro, México. (5) Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, C.P. 76230, A.P. 1-1010, C.P. 76000, México. (6) Posgrado en Alimentos del Centro de la Republica (PROPAC), Facultad de Química, Universidad Autónoma de Querétaro, Qro, México. (7) Corresponding author. Phone: 52-442-2381141. E-mail: <marioga@fata.unam.mx> Cereal Chem. 81(1):65-69. Accepted July 15, 2003. Copyright 2004 American Association of Cereal Chemists, Inc.

Our report shows the calcium ion diffusion process through the different parts of maize kernels (pericarp, endosperm, and germ) during the traditional nixtamalization process as a function of steeping time (t) 0-24 hr. The cooking step of the nixtamalization process used 3 kg of maize kernels in 6L of water and 2% calcium hydroxide (w/w). The cooking temperature was 92°C for 40 min. The calcium content of the samples was measured using atomic absorption spectroscopy. We found that the whole instant corn flour, pericarp, endosperm, and germ, had a nonlinear relationship to steeping time, showing a local maximum at 9 hr. Analysis of the different parts of the nixtamalized kernels showed that in short steeping times (0-5 hr) calcium diffusion took place mainly in the pericarp. Calcium diffusion in the endosperm and germ occurred gradually over longer steeping times. However, the physical state of the kernels (broken kernels) accelerated the diffusion process. Calcium diffusion occurred first in the pericarp, followed by the endosperm and germ. Immediately after cooking (t = 0 hr), we found a 1.148% calcium content in the pericarp, 0.007% in the germ, and 0.028% in the endosperm. After 24 hr of steeping, the calcium contents were 2.714% in the pericarp, 0.776% in the germ, and 0.181% in the endosperm. In another study, the calcium content in the endosperm was measured by first separating the 10% from the outermost, followed by another 10% from the next endosperm tissue, and concluding with the remaining 80%. Calcium ions were present mainly in the outermost layers of the endosperm. The damaged kernels steeped for more than 5 hr showed greater calcium concentrations than the undamaged counterparts.