title: Properties of Particle Size Distribution from Milled White Nixtamalized Corn Kernels as a Function of Steeping Time.
abstract: This paper focuses on the particle size distribution (PSD) changes during nixtamalized corn kernels (NCK) as a function of the steeping time (ST). The process to obtain powder or corn flour from NCK was as follows: (i) the NCK with different STs were wet-milled in a stone mill, (ii) dehydrated by a Flash type dryer, and (iii) pulverized with a hammer mill and sieved with a 20 mesh. The powder was characterized by measuring the PSD percentage, calcium percentage (CP), peak viscosity at 90°C (PV), and crystallinity percentage (CP). The PSD of the powder as a function of ST was determined by sieving in Ro-TAP equipment. By sieving, five fractions of powder were obtained employing meshes 30, 40, 60, 80, and 100. The final weight of the PSD obtained from the sieving process follows a Gaussian profile with the maximum corresponding to the average particle obtained with mesh 60. The calcium percentage as a function of ST follows a behavior similar to the weight of the PSD. The study of crystallinity versus the mesh number shows that it decreases for smaller mesh number. A similar behavior is observed as steeping time increases, except around ST = 8 h where the gelatinization of starch is observed. The trend of increasing viscosity values of the powder samples occurs when increasing ST and decreasing particle size. The ST significantly changes the crystallinity and viscosity values of the powder and, in both cases, a minimum value is observed in the region 7-9 h. The experimental results show that the viscosity increases (decreases) if the particle size decreases (increases).
authors.affiliation: Instituto Politécnico Nacional, CICATA LEGARIA, Calzada Legaria No. 694, Colonia Irrigación, 11500 México, DF, Mexico.
authors.forename: J L
authors.initials: JL
authors.lastname: Fernández-Muñoz
authors.affiliation: Instituto Politécnico Nacional, CICATA LEGARIA, Calzada Legaria No. 694, Colonia Irrigación, 11500 México, DF, Mexico.
authors.forename: M
authors.initials: M
authors.lastname: Zapata-Torrez
authors.affiliation: Departamento de Ingeniería Agrícola, DICIVA, Universidad de Guanajuato, Campus Irapuato-Salamanca, Ex Hacienda el Copal km 9, Carretera Irapuato-Silao, 36500 Irapuato, GTO, Mexico.
authors.forename: A
authors.initials: A
authors.lastname: Márquez-Herrera
authors.affiliation: Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07000 México, DF, Mexico.
authors.forename: F
authors.initials: F
authors.lastname: Sánchez-Sinencio
authors.affiliation: Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07000 México, DF, Mexico.
authors.forename: J G
authors.initials: JG
authors.lastname: Mendoza-Álvarez
authors.affiliation: Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07000 México, DF, Mexico.
authors.forename: M
authors.initials: M
authors.lastname: Meléndez-Lira
authors.affiliation: Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14-740, 07000 México, DF, Mexico.
authors.forename: O
authors.initials: O
authors.lastname: Zelaya-Ángel