Abstract
Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose and storage time on the free radical concentrations in gamma-irradiated dried seasoning powder. Seasoning powders of dried squid flavor, shrimp flavors, kimchi flavor, spicy beef soup flavor and soy sauce flavor were irradiated with doses of 0, 1, 3, 5, 7 and 9 kGy at room temperature using a Co-60 irradiator. Characteristic signals of free radicals were observed in all the irradiated samples of this experimental while these signals were not detected in non-irradiated samples. Since the free radical concentrations linearly increased with the applied doses (1~9 kGy), highly positive correlation coefficients ($R^2$ = 0.9285~0.9965) were obtained between irradiation doses and free radical concentrations during all the storage times. Free radical concentrations of the irradiated flavored seasoning powder did not change even at 16 weeks of storage at room temperature, while those of dried squid, shrimp and spicy beef soup flavors decreased until 2 weeks of storage after irradiation with 5 kGy or over, and these of soy cause flavors slowly decreased until 8 weeks of storage after irradiation with 3 kGy or over. Although the free radical concentrations decreased with storage times, the characteristic signals of the irradiated seasoning powders of dried squid, shrimp, spicy beef and soy sauce flavors were observed even after 16 weeks of storage at room temperature.
