title: Starch-guar gum extrudates: microstructure, physicochemical properties and in-vitro digestion.
abstract: Starch-guar gum mixtures were obtained by extrusion using a three-variable Box-Behnken statistic design. Morphology, expansion index, viscosity, crystallinity and digestion in vitro of the extruded samples were analyzed through response surface methodology (RSM). The extrusion temperature and the moisture content were the factors that significantly affected the physicochemical properties of the samples. Starch-guar gum samples showed expansion index and viscosity up to 1.55 and 1400mPas, respectively. The crystallinity of the samples was modified by adding guar gum to the extrudates, showing correlation between long-range order (X-ray diffraction) and short-range order (FTIR spectroscopy). Guar induced microstructural changes and its role in gelatinization-melting processes was significant. The rate of glucose release decreased from 0.47 to 0.43mM/min when the extrusion temperature decreased. However, adding guar gum to starch had no significant effect on glucose release. Overall, the extrusion temperature and the moisture content were the factors that significantly affected the physicochemical properties of the extruded samples.
authors.affiliation: Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Col. Irrigación, C.P. 11500 México D.F., Mexico. Electronic address: evborries@hotmail.com.
authors.forename: Erich
authors.initials: E
authors.lastname: von Borries-Medrano
authors.affiliation: Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Col. Irrigación, C.P. 11500 México D.F., Mexico. Electronic address: mjaimef@ipn.mx.
authors.forename: Mónica R
authors.initials: MR
authors.lastname: Jaime-Fonseca
authors.affiliation: Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Legaria 694, Col. Irrigación, C.P. 11500 México D.F., Mexico. Electronic address: miguel_agme@hotmail.com.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Aguilar-Méndez
mesh_terms: D055598:Chemical Phenomena; D005685:Galactans / Q000737:chemistry*; D008351:Mannans / Q000737:chemistry*; D053149:Plant Gums / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D014867:Water; D013213:Starch; C007894:guar gum
keywords: Corn starch; Extrusion; Guar gum; In-vitro digestion; Microstructure; RSM