Identification of radiation processing of different plant foods of Pakistan origin using the rapid technique of Electron Spin Resonance (ESR) spectrometry

Electron Spin Resonance (ESR) spectrometry is a potential technique for detection of irradiated foods like plant foods, which contain cellulosic materials as well as low molecular weight sugars and like the meat and fish, which contain bones. This study is focused on identification of irradiated foods such as tree nuts (pine nuts and walnuts), beans and pulses (red grams, white beans, pinto beans and green peas), and food containing low molecular weight sugars (pan masala and dried dates). The food samples were obtained from Pakistan and exposed to different permissible doses of radiation using electron beam linear accelerator. The control and irradiated samples were kept at room temperature in the laboratory for the record of ESR spectra. For post-irradiation stabilities the food samples were analysed at different intervals of time (15, 90 and 300 days). The controlled samples in case of cellulosic foods showed ESR signal at g0 = 2.004 and irradiated samples were shown with triplet signal indicative of the presence of radiation-induced cellulose radicals. Similarly, in case of Pan Masala and dried dates, a straight signal at zero level was observed for un-irradiated samples and a complex ESR signal was appeared for irradiated samples. The observed radiation-induced signals were dose-dependent and showed an increasing trend with an increase in radiation dose. The comparison of intensities of ESR signals was also carried out along with the study of post-irradiation stabilities of the ESR signals and method proved to be valid for differentiation of controlled and irradiated samples of food.