SEM studies of the structure of the gels prepared from untreated and radiation modified potato starch

• Four procedures of the preservation of starch gels for SEM studies were applied.
• The ability to observe the radiation effect by SEM was assessed for each method.
• Dose dependent changes in the gel structure were discovered.
• It was related to decrease in the swelling power and decreased viscosity of the gels.
• A hot-stage microscope was applied in order to follow the gelatinization process.

Potato starch was irradiated with a 60Co gamma rays using doses of 5, 10, 20 and 30 kGy. Gels containing ca. 9.1% of starch were prepared by heating the starch suspensions in the heating chamber stabilized at 100 °C. Four procedures were applied for preparation of the samples in regard to SEM studies and the ability to observe the radiation effect by SEM was assessed for each method. Differences were observed between the SEM images recorded for the non-irradiated samples prepared using all the methods, and those irradiated. Images of the non-irradiated gels indicate generally a honey-comb structure, while smooth areas but with oriented fractures has appeared after irradiation. Modification of gel structure corresponds to the applied dose. The results were related to the process of gel formation (as observed by means of the hot stage microscope) to decrease in swelling power of the irradiated starch and to decreased viscosity of the resulting gels. It can be concluded that the differences in structural properties of gels shown by SEM result probably due to the better homogenization of the gels formed after radiation induced degradation.