Effect of moisture on technological properties of corn starch modified by the electron beam irradiation

Abstract

Electron beam irradiation is one of the most effective starch modification methods. Moisture is one of the factors that is affected by the irradiation via the free radical formation. The effect of the moisture content on the technological properties of irradiated starch samples was studied. The moisture content of corn starch samples in this study was adjusted at 9.08, 12.96, 15.06, 20.39 and 29.09% (w w). Corn starch samples were irradiated at 5 kGy. Color, free acid, solubility, swelling, transparency, syneresis and starch gel structure were studied to elucidate the effect of the moisture on technological properties of corn starch treated by electron beam. The results showed that electron beam radiation caused starch samples at different moisture to break into small molecules due to the separation of the glycosidie bonds. Thus, free acid, swelling, solubility of irradiated starch samples were higher than those of natural starch samples and were increased with low moisture content. The results also indicated that electron beam treatment increased the syneresis of irradiated starch samples. The texture profile analysis (TPA) of starch gel structure showed that textural properties such as hardness, elasticity and chewiness of irradiated starch samples were higher than those of natural starch samples.