Ultrasound treatments of tef [Eragrostis tef (Zucc.) Trotter] flour rupture starch ?-(1,4) bonds and fragment amylose with modification of gelatinization properties

Tef is a nutritionally-rich ancient grain gaining increasing interest in gluten-free market. Molecular and structural properties the main biopolymers of two Spanish ecotypes tef flour physically modified by ultrasound (US) treatments under different temperatures (20, 40, 45, 50 55 °C) were studied. Modifications achieved dependent on ecotype, where white presented higher susceptibility. Size-exclusion chromatography indicated proportion intermediate amylose chains (degree polymerization 300–1600) across whole chain-length distribution amylose/amylopectin ratio, that increased up to 23% 19% treated samples brown respectively. US starch short-range order crystallinity promoted formation random coil protein structure disappearance ?-sheet, as confirmed from FTIR spectroscopy. XRD 1H NMR revealed fragmentation ?-(1,4) than ?-(1,6) bonds due ultrasonication. The gelatinization temperature range ?Hgel decreased after ultrasonication 6 °C 13%, an effect was reinforced or counteracted, respectively, treatment temperature, indicating annealing modulates impact sonication properties. found be significantly treatments, determining variable influencing degree modification achieved.