Abstract
The paper presents the experimental results regarding the investigation of some physico-chemical and structural characteristics of starch modified by electron beam and microwave combined treatment. The combined electron beam (EB) and microwave (MW) treatment of granular starch was performed in four different regimes, successive and simultaneous. The experimental data showed that the acidity of starch aqueous solutions increased while the apparent viscosity reduced as a function of the treatment parameters and regime. No significant changes appeared in the morphological characteristics of the samples treated with combined EB-MW, but the spectral characteristics suffered minor changes suggesting that the stability of hydrogen inter- and intramolecular bonds is affected. At the same time, the degree of order increased after successive combined treatments indicating some molecular associations or rearrangements in amorphous component of starch due to the microwave field. The evolution of the molecular weights and molecular weight distribution indicated that the macromolecular degradation cannot be correlated with the specific absorbed energy as a consequence of the microwave field contribution. Keywords: starch, electron beam, microwave, viscosity, SEM, GPC