Demonstration of irradiation in onions

Two onion varietics (Vsetana and Hiberna) were used for the experiments. Radiation treatment was carried out not later than 25 days after harvesting with a 80 Gy dose of gamma radiation. Following treatment the onions were stored at temperatures between 9 and 21.5 degC and a relative humidity of 30 to 76%. Samples were taken at about one month intervals of irradiated and non-irradiated onions of both varieties and the content of deoxysaccharides determined. The concentration in non-irradiated onions was 0.27x10-4% in the Vsetana variety and 0.33x10-4% in the Hiberna variety. In the radiation treated samples the concentrations were higher: 0.65x10-4% in the Vsetana variety and 0.68x10-4% in the Hiberna variety. Samples of the Vsetana variety were further irradiated with doses of 0, 80, 150, 250, 500, 750 and 1000 Gy of gamma radiation and the content of deoxysaccharides determined. It was found that the concentration of deoxysaccharides is in linear dependence on the applied dose, this within the range of 0 to 250 Gy. In this dose range it is possible to determine the absorbed dose from the content of deoxysaccharides. Model solutions were prepared according to the chemical composition of the onions (tabulated). The solutions were irradiated with a dose of 1000 Gy under the same conditions as the onions. The deoxysaccharide concentration in irradiated model solutions was proportional to the concentration of those saccharides which in the solutions were contained in the highest concentration (glucose, saccharose, raffinose). All obtained results are summed up in tables and discussed in great detail. (E.S.) 4 tabs., 1 fig., 29 refs