title: Physico-chemical, nutritional and infrared spectroscopy evaluation of an optimized soybean/corn flour extrudate.
abstract: A central composite design using RMS (Response Surface Methodology) successfully described the effect of independent variables (feed moisture, die temperature and soybean proportion) on the specific parameters of product quality as expansion index (EI), water absorption index (WAI), water solubility index (WSI) and total color difference (ΔE) studied. The regression model indicated that EI, WAI, WSI and ΔE were significant (p < 0.05) with coefficients of determination (R(2)) of 0.7371, 0.7588, 0.7622, 0.8150, respectively. The optimized processing conditions were obtained with 25.8 % feed moisture, 160 °C die temperature and 58 %/42 % soybean/corn proportion. It was not found statistically changes in amino acid profile due to extrusion process. The electrophoretic profile of extruded soybean/corn mix presented low intensity molecular weight bands, compared to the unprocessed sample. The generation of low molecular weight polypeptides was associated to an increased in In vitro protein digestibility (IVPD) of the extrudate. The FTIR spectra of the soybean/corn mix before and after extrusion showed that the α-helix structure remained unchanged after extrusion. However, the band associated with β-sheet structure showed to be split into two bands at 1624 and 1640 cm(-1) . The changes in the β-sheet structures may be also associated to the increased in IVPD in the extruded sample.
authors.affiliation: Departamento de Graduados en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Col. Sto. Tomás, México, D.F. C.P. 11340 México.
authors.forename: Fabiola Araceli
authors.initials: FA
authors.lastname: Guzmán-Ortiz
authors.affiliation: Departamento de Graduados en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Col. Sto. Tomás, México, D.F. C.P. 11340 México.
authors.forename: Humberto
authors.initials: H
authors.lastname: Hernández-Sánchez
authors.affiliation: Escuela Superior de Físico Matemáticas, Laboratorio Espectroscopia Mössbauer y Técnicas Complementarias, Departamento de Física, Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional S/N Edificio 9, U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, Mexico, D.F. C.P.07738 México.
authors.forename: Hernani
authors.initials: H
authors.lastname: Yee-Madeira
authors.affiliation: Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Instituto Politécnico Nacional, Calzada Legaria No. 694 Col. Irrigación, Del. Miguel Hidalgo, Mexico, D.F. C.P. 11500 México.
authors.forename: Eduardo
authors.initials: E
authors.lastname: San Martín-Martínez
authors.affiliation: Departamento de Graduados en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Col. Sto. Tomás, México, D.F. C.P. 11340 México.
authors.forename: María Del Carmen
authors.initials: Mdel C
authors.lastname: Robles-Ramírez
authors.affiliation: Centro de Investigación en Biotecnología Aplicada. ExHacienda San Juan Molino. Carretera Estatal, Tecuexcama-Tepetitla Km. 1.5, Tlaxcala, Tlax. C.P. 90700 México.
authors.forename: Marlon
authors.initials: M
authors.lastname: Rojas-López
authors.affiliation: Processed Foods Research Unit. USDA-ARS-WRRC, Albany, CA USA.
authors.forename: Jose De J
authors.initials: Jde J
authors.lastname: Berríos
authors.affiliation: Departamento de Graduados en Alimentos, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Carpio y Plan de Ayala S/N, Col. Sto. Tomás, México, D.F. C.P. 11340 México.
authors.forename: Rosalva
authors.initials: R
authors.lastname: Mora-Escobedo
keywords: Amino acid profile and electrophoresis; Extrusion cooking of soybean/corn; In vitro protein digestibility; Infra-red spectroscopy (FTIR); Protein changes; Response surface methodology