Abstracts Book - IMRC 2018

• SB1-P015
THE INTERPRETATION OF WIDE-ANGLE X-RAY SCATTERING
CURVES IN ISOLATED STARCHES. THE IDENTIFICATION OF
LAMELLAR STRUCTURE
Mario Rodriguez Garcia 1 , Sandra Milena Londoño Restrepo 2 , Cristian Felipe Ramirez Gutierrez 2 ,
Batriz Marcela Millán Malo 1 , Eric Mauricio Rivera Muñoz 1
1
Universidad Nacional Autónoma de México, Departamento de Nanotecnología, Centro de
Física Aplicada y Tecnología Avanzada, Mexico. 2 Universidad Nacional Autónoma de México,
Posgrado en Ciencia e Ingeniería de Materiales, Mexico.
The existence of different starch crystalline structure polymorphism A, B, C, and
V types is commonly accepted. However, these polymorphisms had not been
well interpreted according to their WAX curves. The deconvolution of the
patterns used in the fitting process to characterize these polymorphism does
not make sense, being as the scattering contribution due to nano-size crystal
has not been considered. A simulation of the effect of the crystal size on the
shape and width on the WAX curves shows that the scattering phenomenon
governs the so-called X-ray diffraction patterns of starches due to the nano-size
crystal and the amorphous contribution of the amylose and/or amylopectin
fractions. The peak located at 5.64° present in some isolated starches of potato,
achira, cassava, jicama, Peruvian bean, lentil, cornstarch rich in amylose and
plantain does not identify any polymorphism; this peak could be the result of a
lamellar formation of a crystalline structure of the polysaccharides.
Keywords: amylose, amilopectine, WAXS
Presenting authors email: marioga@fata.unam.mxa