Development of ESR method for gamma-irradiated lactose powders

In this study, ESR was used to characterize the differences between irradiated lactose and non-irradiated lactose. A multi-component ESR spectrum was observed from most of the non-irradiated commercial lactose powder as well as the gamma-irradiated lactose powder. However, the signal pattern of non-irradiated lactose powder was different from that of irradiated lactose powder. Moreover, the multi-component ESR spectrum intensity of radicals generated by milling was weaker than that by gamma-irradiation. Among the several possible causes of generating radicals such as irradiation, lipid oxidation, protein oxidation, influence of ash or mineral and mechanical radical by grinding, the multi-component ESR spectrum from the non-irradiated lactose powder was shown to have resulted from the generation of mechanical radicals during milling in the manufacturing processes.