Cereal Chem. 79(1):138-142The glass transition temperature of gluten at different moisture levels was determined by differential scanning calorimetry and mechanical spectrometry. The dynamic moduli (G' and G") of gluten with 10-40% moisture were measured as a function of temperature by pressure rheometry. At 10% moisture, gluten exhibited entangled polymer flow at 92-140°C and networking reactions at higher temperatures. At higher moisture levels, gluten experienced structured flow before networking cross-linking reactions. The onset temperature of the reaction zone was 120°C in 20% moisture gluten and 93ºC at moisture levels of 30-40%. Softening of the vitrified network occurred at 184, 181, and 170ºC in 20, 30, and 40% moisture gluten, respectively. A preliminary state diagram of gluten as a function of moisture and temperature was developed.
Cereal Chem. 78(3):226-230Extrudate expansion of cereal-based products is largely dependent on the molecular interactions and structural transformations that proteins undergo during extrusion processing. Such changes strongly influence the characteristic rheological properties of the melt. It is possible to modify rheological properties of wheat flour during extrusion processing, in particular shear viscosity, with cysteine. The objective of this work was to further develop an understanding of the molecular interactions and structural transformations of wheat flour from dynamic oscillatory rheological measurements. Temperature and frequency sweeps were conducted in the linear viscoelastic range of the material. Changes in the storage modulus (G′), the loss modulus (G′′) and the loss tangent (tan δ) of 25% moisture wheat flour disks as a function of cysteine concentration (0-0.75%) were monitored. Molecular weight between cross-links (M c ) and the number of cross-links (N c ) per glutenin molecule were determined from frequency sweep data. Increasing cysteine concentration broke crosslinks by decreasing G′ maximum and increasing tan δ values. Molecular weight between cross-links increased and the number of cross-links decreased. G′ values from temperature sweeps showed a similar trend. This information leads to a better understanding of the viscoelastic behavior of wheat flour doughs during extrusion cooking and elucidation of protein-protein reaction mechanisms and other interactions in extruded cereal-based snack foods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.