Studies on the Microstructure and Thermal Properties of Pulsed Electric Fields (PEF)-Treated Maize Starch

Abstract

Maize starch-water suspensions (8.0%) were submitted to the pulsed electric fields (PEF) with different electric field strength and treatment time up to 50 kV/cm and 1272 μs. Samples were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR). GPC analysis showed that molecular weights (Mw and Mn) were decreased with increasing electric field strength and treatment time. DSC studies showed a decrease in gelatinization temperatures (To and Tp) and the enthalpy of gelatinization (ΔHgel) with increasing electric field strength and treatment time. It was explored that electric field strength played a dominant role in the PEF treatments. On the other hand, it was demonstrated from NMR and TGA analysis that no significant difference among the native and PEF-treated maize starches was obtained, which indicated that PEF treatments did not affect the chemical structure of maize starch.