Macromolecular degradation of extruded starches measured by HPSEC-MALLS | [Degradation macromoleculaire d'amidons extrudes mesures par HPSEC-MALLS]
1999
Baud, B. (Institut National de la Recherche Agronomique, Nantes (France). Centre de Nantes, Unite de Recherche sur les Polysaccharides leurs Organisations et Interactions) | Colonna, P. | Della Valle, G. | Roger, P.
Maize starches with various amylose contents (0, 23, 47, 70 %) were processed on a twin screw extruder under various conditions of temperature Tp (100-185 degrees), moisture content MC (2-33% on a total weight basis) and specific mechanical energy SME (100-580 kWh/t) during processing. Degraded starches are dispersed in 95% dimethylsulphoxide and solubilized in water with high yields (86%). High performance size exclusion chromatography coupled on-line with multiple angle laser light scattering (HPSEC-MALLS) method was used to determine the molecular weight distribution (MWD), the number-average MA and weight-average Mw molar masses of each sample. Sample recoveries after chromatography are higher than 90%. Compared with those obtained for native starches, MWD changes for extruded products underlined the disappearance of the high molecular weight fractions and MA and Mw decreased. Negative influence of SME on MA was all the more significant as amylose content decreased. The molecular degradation affects more amylopectin than amylose, due to the higher molecular weight of the first one
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