Electron spin resonance investigation of free radicals produced in pulverized non-irradiated sugar

An electron spin resonance (ESR) study of the effects of pulverization on non-irradiated crystalline sugar was performed. It indicated that the crystalline sugar before being ground did not give any ESR signal but an ESR signal was found in pulverized sugar. These results implied that free radicals were produced by pulverization. Moreover, the free radical density increased as the particle size decreased. From high-performance liquid chromatography analysis and the ESR spectrum of non-irradiated powdered sucrose, it can be inferred that the pulverization-induced free radical in sugar is a sucrose radical. Recently, many researchers have reported that sugar irradiated with ⁶⁰Co γ-rays at different doses produced stable sucrose radicals. This may imply that the process of sucrose radical formation by mechanical stress is similar to that for irradiation.