Changes in Selected Nutrients and Microstructure of White Starch Quality Maize and Common Maize During Tortilla Preparation and Storage

2004 ◽  
Vol 10 (2) ◽  
pp. 79-87 ◽  
Author(s):  
R. Mora-Escobedo ◽  
P. Osorio-Diaz ◽  
M. I. Garcia-Rosas ◽  
A. Bello-Perez ◽  
H. Hernandez-Unzon
Keyword(s):  
Differential Scanning Calorimetry ◽  
High Temperature ◽  
Structural Changes ◽  
Prolonged Storage ◽  
Starch Granules ◽  
Scanning Calorimetry ◽  
Starch Quality ◽  
Starch Retrogradation ◽  
And Storage ◽  
Starch Crystallinity

Raw maize, masa, and fresh and stored tortillas of white starch quality maize (Costeno) and common maize were analysed for chemical composition, dietary fibre, digestible (DS) and resistant (RS) starches. Changes in starch crystallinity and microstructure were also evaluated. Protein content was lower in masa and tortillas than in the original maize samples. Insoluble (IDF) and soluble (SDF) dietary fibres were higher in Costeno than in common maize, but stored tortillas showed the highest value in both samples. DS decreased and RS increased during tortillas storage, made with both starches. The development of RS explained the observed decrease in DS in masa (enthalpy of gelatinisation). Differential scanning calorimetry studies showed peak gelatinisation temperatures (Tp) of 75.1 and 69.4 C for Costeno and common maize respectively. Masa of common maize showed a second transition endotherm (Tp, 108.9 C) which corresponded to amylose–lipid complexation. Tortillas with 5 and 10 days of storage showed an endothermic event at 53 and 55.7, and 54.5 and 59.9 C for Costeno and common maize respectively, due to starch retrogradation. These values were in accordance with the higher total RS contents recorded after prolonged storage. Microscopic structures for masa and fresh tortillas showed that the high temperature imposed on the masa and the influence of mechanical stress during tortillas making were great enough to disrupt starch granules. In general, structural changes were in agreement with changes in starch.

scholarly journals Influence of trehalose, glucose, fructose, and sucrose on gelatinisation and retrogradation of corn and tapioca starches

2009 ◽  
Vol 27 (No. 3) ◽  
pp. 151-157 ◽  
Author(s):  
J. Babić ◽  
D. Šubarić ◽  
B. Milicevic ◽  
D. Ačkar ◽  
M. Kopjar ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Corn Starch ◽  
Storage Temperature ◽  
Storage Period ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Starch Retrogradation ◽  
And Storage

The effects of trehalose, glucose, fructose, and sucrose on the gelatinisation and retrogradation properties of corn (CS) and tapioca (TS) starches were studied with differential scanning calorimetry (DSC). The results showed that the sugars affect gelatinisation and retrogradation of both starches, with the effect varying significantly between sugars. The addition of trehalose, glucose, fructose, and sucrose increased the gelatinisation temperatures and enthalpy of gelatinisation of corn and tapioca starches. The extent of increase followed the order: fructose < glucose < trehalose < sucrose with CS, and fructose < trehalose < sucrose < glucose with TS. The retrogradation studies showed that sugars of lower molecular weights (glucose and fructose) were less effective in the reduction of retrogradation than those of higher molecular weights (sucrose and trehalose). Trehalose retarded retrogradation of both corn and tapioca starches under all conditions investigated. Sucrose had the same effect on the corn starch retrogradation. The effects of other sugars depended on the type of starch, storage period, and storage temperature.

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

Preparation and Crystallization Kinetics of FeSiB Amorphous Ribbons under Non-Isothermal Regime

2014 ◽  
Vol 605 ◽  
pp. 35-38
Author(s):  
Eirini Varouti
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Chemical Composition ◽  
Crystallization Kinetics ◽  
Structural Changes ◽  
Scanning Calorimetry ◽  
Amorphous Ribbons ◽  
Isothermal Regime ◽  
Kinetics Of

The aim of the present work was the preparation and characterization of FeSiB amorphous magnetic ribbons with the following chemical composition: Fe80SixB20-x, x=5,6,8 and Fe75Si15B10. Differential Scanning Calorimetry was employed in order to study the thermal stability and structural changes during the transformations that took place. Much emphasis is placed on the analysis of the crystallization kinetics.

Multiple dielectric anomalies in xBiLaO3–(1 − x)PbTiO3 piezoelectrics

2008 ◽  
Vol 23 (2) ◽  
pp. 565-569 ◽  
Author(s):  
Runrun Duan ◽  
Michael S. Haluska ◽  
Robert F. Speyer
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Excellent Agreement ◽  
Structural Changes ◽  
Dielectric Anomaly ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermally Induced ◽  
X Ray ◽  
Higher Temperature

Compositions of xBiLaO3–(1 − x) PbTiO3 over the range 0 ≤ x ≤ 0.225 were calcined and sintered. The dielectric constant with temperature and differential scanning calorimetry measurements were in excellent agreement with respect to Curie-like tetragonal to cubic transformations starting at 495 °C for pure PbTiO3, shifting to lower temperatures with increasing x. For compositions of x ≥ 0.05, a second higher-temperature (∼600 °C) endotherm, and matching dielectric anomaly, were consistently observed, for which there were no structural changes indicated by hot-stage x-ray diffraction. This transformation was speculated to be based on a thermally induced desegregation of B-site cations.

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