Irradiation and storage effects on some properties of potato starch and use of thermoluminescence for identification of irradiated tubers

The effect on properties of starch isolated from Ajax and Diamant potatoes freshly harvested and irradiated immediately after harvest and after two we eks with 0.05, 0.10, 0.15, and 0.20 kGy were reported. Changes due to posti rradiation storage up to six months at two different conditions (5 C, 90+/- 2% RH and 20 C, 79+/-5% RH) were also studied. Swelling power (SP) slightly decreased or remained unchanged with different irradiation dose, but the e ffect of timing of irradiation after harvest was significant. Doses of 0.2 and 0.15 kGy significantly (p less than or equal to 0.05) increased solubil ity, particularly at 90 C solubility temperature compared to lower doses. D ecrease in viscosity with increasing dose immediately after irradiation was observed in both varieties but was more pronounced in Diamant. However, ch anges were dependent on variety, irradiation dose, timing of irradiation, a nd postirradiation storage conditions. Viscoamylograph test showed that 0.2 kGy significantly (p less than or equal to 0.05) increased transmission te mperature (TT) and temperature at maximum viscosity (TMV), but decreased th e maximum viscosity immidiately after irradiation. The same trend was estab lished during the post-irradiation storage time, particularly in Ajax starc h, regardless of timing of irradiation or storage conditions. Thermolumines cence (TL) glow curves exhibited qualitative differences between irradiated and unirradiated tubers during the entire storage period, but dose estimat ion could not be determined.