title: Physicochemical, rheological and structural characteristics of starch in maize tortillas.
abstract: Fresh and stored maize (white and blue) tortillas were evaluated for physicochemical, rheological and structural characteristics assessed by calorimetry, x-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, dynamic viscoelastic tests, and high-performance size-exclusion chromatography. Two endotherms were found in studies of fresh and stored tortillas. The low temperature endotherm (50-56 degrees C) was due to reorganized (retrograded) amylopectin, while the high temperature endotherm (105-123 degrees C) was attributed to retrograded amylose. The enthalpy value for the lower temperature transition was minor than that of the high temperature transition. Fresh tortillas showed an amorphous starch arrangement by x-ray diffraction study. Stored samples showed the presence of peaks at 2theta = 17 masculine and 23 masculine, indicating re-crystallization of starch components. FTIR results confirmed the development of higher levels of starch crystals during storage. Differences in the viscoelastic parameters were also observed between fresh and stored samples. At the longest storage times, white tortillas were more rigid than blue tortillas. Molar mass values for starch increased for both white and blue tortillas as storage time progressed, though relatively higher values were obtained for white tortillas. More starch reorganization occurred in white tortillas, in accordance to calorimetric, x-ray diffraction, FTIR and rheological results. These results corroborate that changes occurring in tortillas during storage are related to reorganization of starch components, and the maize variety more than the color plays an important role.
authors.affiliation: Centro de Desarrollo de Productos Bióticos del IPN, Km 8.5 Carr. Yautepec-Jojutla, Colonia San Isidro, Apartado Postal 24, 62731, Yautepec, Morelos, México.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Hernández-Uribe
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Ramos-López
authors.forename: Hernani
authors.initials: H
authors.lastname: Yee-Madeira
authors.forename: Luis A
authors.initials: LA
authors.lastname: Bello-Pérez
mesh_terms: D000687:Amylopectin / Q000737:chemistry; D000688:Amylose / Q000737:chemistry; D001939:Bread / Q000032:analysis*; D002151:Calorimetry; D003460:Crystallization; D004548:Elasticity; D005511:Food Handling / Q000379:methods; D012212:Rheology; D012639:Seeds; D017550:Spectroscopy, Fourier Transform Infrared; D013213:Starch / Q000032:analysis / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity; D014961:X-Ray Diffraction; D003313:Zea mays
chemical_list: D013213:Starch; D000688:Amylose; D000687:Amylopectin
references.citation: Int J Biol Macromol. 2002 Dec 20;31(1-3):79-85
references.pmid: 12559430
references.citation: Plant Foods Hum Nutr. 2009 Mar;64(1):18-24
references.pmid: 19153833
references.citation: J Agric Food Chem. 2005 Feb 9;53(3):495-501
references.pmid: 15686392
references.citation: Int J Biol Macromol. 2006 Dec 15;40(1):59-63
references.pmid: 16806453
references.citation: J Sci Food Agric. 2007 Nov;87(14):2733
references.pmid: 20836185
references.citation: Plant Foods Hum Nutr. 2008 Sep;63(3):119-25
references.pmid: 18600459
references.citation: Plant Foods Hum Nutr. 2004 Spring;59(2):51-4
references.pmid: 15678751
references.citation: Arch Latinoam Nutr. 2001 Jun;51(2):187-94
references.pmid: 11678051