Identification of dehydrated spices and herbs subjected to the irradiation process

This research shows the possibility of determining through a combination of analytical methods whether dehydrated spices and herbs were irradiated. The methods used were the following: viscosimetry, thermoluminescence (TL) and electron paramagnetic resonance (EPR). Viscosimetry was applied in suspensions of dehydrated and irradiated spices and herbs which had been gellified by heat. It was observed that the viscosity of the samples decreases when the radiation dose increases. It was also observed that the temperature of the gelification is linked to the viscosity. The variation of the capability of gelification of the samples in relation to the storage time (30 and 60 days) does not have any consequence on the viscosity. Thermoluminescence is based on the transference of electrons to an excited state by ionizing radiation with emission of light when the electrons thermally stimulated. The thermoluminescent signals of the spices can be explained by the presence of mineral grains adhering to the surface of the samples. The thermoluminescent signal increased in intensity with the amplification of the radiation dose. The study of the signal in relation to the storage time (30 and 60 days) showed that it weakened and decreased. Free radicals produced by irradiation of spices were analyzed by the electron spin resonance method (ESR). It was checked that increasing the radiation dose meant an intensification of the ESR signal. Within a 30 day storage time, a fading of the signal was observed. The results of this study lead us to the following conclusion: viscosimetry, thermoluminescence and electron spin resonance are methods of analysis which are proper to detect whether dehydrated spices and herbs were irradiated, especially when these different methods were used in combination. (author)