Abstract: In this study, the structural properties of degerminated corn starch modified by enzymatic extrusion, such as crystallinity and morphological structure, were analyzed by X-ray diffraction, polarizing microscope, scanning electron microscope, hot-stage microscope, differential scanning calorimetry and Fourier transform infrared spectroscopy. The physicochemical properties of native, extruded and enzymatic extruded degerminated corn starch, including enzymatic hydrolysis, iodine blue value, gelatinization degree and amylose content, were studied by using various techniques such as differential scanning calorimetry and Fourier transform infrared spectroscopy. Extrusion and enzymatic extrusion had great influence on starch structure and properties. Enzymatic extrusion could increase the efficiency of enzymatic hydrolysis and the degree of gelatinization degerminated corn, and decrease iodine blue value and amylase content. The morphology and birefringence of enzymatic extruded degeminated corn starch granules was partially destroyed and aggregation of starch granules was observed. The enthalpy change of gelatinization was reduced. The crystal structure of starch granules was destroyed, along with a significant decrease in the degree of crystallinity. The broken starch granules were susceptible to gelatinization and decomposition.

Key words: starch, extrusion, degerminated corn, structure, physicochemical properties