Analysis of molecular mobility in corn and quinoa flours through ¹H NMR and its relationship with water distribution, glass transition and enthalpy relaxation
Solids-water interactions of corn and quinoa flours were evaluated through 1H NMR, DSC, and water sorption isotherms. Glass transition temperature (Tg), observed by DSC, was better distinguished through FID signals, and correlated to water content through the Gordon and Taylor model. Enthalpy relaxations, identified by thermal analysis at 50–70 °C were studied through transverse relaxation times (T2) measured after Hahn spin-echo sequence, which revealed a rearrangement of the biopolymers structures that cause immobilization of polymer chains and reduced mobility of water molecules with weak interactions with solids (lower T22). The higher lipid content of quinoa flour was manifested after the CPMG sequence (T2 ≈ 100 ms) and caused reduced hygroscopicity and Tg values compared with corn flour systems. 1H NMR resulted efficient for assigning proton populations and understanding the changes in their distribution with temperature, analyzing glass transition and interpreting the implications of enthalpy relaxations processes in corn and quinoa flours.
| Main Authors: | , , |
|---|---|
| Format: | info:ar-repo/semantics/artículo biblioteca |
| Language: | eng |
| Published: |
Elsevier
2021-03
|
| Subjects: | Alimentos, Productos Derivados de Cereales, Harina de Maíz, Quinua, Calidad de los Alimentos, Análisis de Alimentos, Almacenamiento, Polimeros, Higroscopicidad, Foods, Cereal Products, Corn Flour, Food Quality, Food Analysis, Storage, Polymers, Hygroscopicity, Isotermas de Sorción de Agua, Movilidad Molecular, Temperatura de Transición del Vidrio, Relajación de la Entalpía, Quinoa, |
| Online Access: | http://hdl.handle.net/20.500.12123/10970 https://www.sciencedirect.com/science/article/pii/S0308814621024286 https://doi.org/10.1016/j.foodchem.2021.131422 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Solids-water interactions of corn and quinoa flours were evaluated through 1H NMR, DSC, and water sorption isotherms. Glass transition temperature (Tg), observed by DSC, was better distinguished through FID signals, and correlated to water content through the Gordon and Taylor model. Enthalpy relaxations, identified by thermal analysis at 50–70 °C were studied through transverse relaxation times (T2) measured after Hahn spin-echo sequence, which revealed a rearrangement of the biopolymers structures that cause immobilization of polymer chains and reduced mobility of water molecules with weak interactions with solids (lower T22). The higher lipid content of quinoa flour was manifested after the CPMG sequence (T2 ≈ 100 ms) and caused reduced hygroscopicity and Tg values compared with corn flour systems. 1H NMR resulted efficient for assigning proton populations and understanding the changes in their distribution with temperature, analyzing glass transition and interpreting the implications of enthalpy relaxations processes in corn and quinoa flours. |
|---|