Physicochemical and Functional Properties of Cassava Starch from Different Varieties as Affected by Gamma Irradiation

The most commonly consumed essential edible crop in many tropical countries in Africa, South America, and Asia is Cassava (Manihot esculenta Crantz). There are limitations on the utilization of cassava roots by processors, and they are also highly perishable and bulky. Raw cassava starches are excessively weak in terms of their structure and functionality, hence, limiting the diversity of industrial applications. The objective was to estimate the outcome of gamma irradiation as an amending agent on raw cassava starch from three cassava types (Ankra, Bosome nsia and TME419). Ankra, Bosome nsia and TME419 were the cassava varieties used for the study. The cassava starch was extracted, and then modified using cobalt-60 source. The administered doses were 5, 10, 15 and 20 kGy at a dose rate of 2.087 kGy/hr, and using zero as the control. The physicochemical and functional properties of the raw and modified cassava starches were evaluated using standard procedures. Gamma irradiation significantly reduced the amylose and carbohydrate contents as well as the colour of cassava starch. Amylose content of Ankra, Bosome nsia and TME 419 were 14.45, 16.39 and 18.21%, respectively. Also, the irradiation reduced the amylose content from 20.21% (control) to 17.47, 15.98, 14.99 and 13.27% at 5-20 kGy, respectively. The carbohydrate content of 44.44, 44.09 and 27.28% were recorded for Ankra, Bosome nsia and TME 419, respectively. Further, the irradiation decreased the carbohydrate content from 48.08% (control) to 45.63, 36.81, 34.94 and 27.54% at 5-20 kGy, respectively. The irradiation doses did not significantly affect the emulsion capacity and stability, and bulk density. The swelling power decreased as the radiation dose increased while solubility index, water and fat absorption capacities and least gelation significantly increased with the radiation dose. Therefore, gamma irradiation could be exploited to alter cassava starch for industrial applications likewise a chemical modification.