Physiological and Biochemical Effects of Gamma Radiation on Tubers of Jerusalem Artichoke

Abstract

1. High doses of gamma radiation (over 2 x 106 reps) caused softening and disintegration of tubers of Jerusalem artichoke (Helianthus tuberosus L.). 2. Darkening of the epidermis and enzymatic (oxidative) activity in the tubers were directly correlated with irradiation doses between 1 x 106 to 4 x 106 reps. With 8 x 106 and 10 x 106 reps these effects were diminished, and with doses above 20 x 106 reps color was more like the controls. 3. Chemical analysis of ethanol slurries of irradiated and non-irradiated tubers indicated that the amounts of reducing sugars, acidity, and permanganate values were positively, and the amounts of inulin, crude fiber, and pectic substances inversely, correlated with radiation dose; total solids and total sugars remained fairly constant. Viscosity of the slurries was approximately constant up to the dose of 4 x 106 reps. On the other hand, the viscosity was reduced with doses from 8 x 106 to 20 x 106 reps but increased with doses of 40 x 106 and 60 x 106 reps. 4. A complete hydrolysis of inulin to fructose in the irradiated (60 x 106 reps) tubers was accomplished by a 1 M HCl treatment at 176⚬ F. for 10 minutes. This was confirmed by paper chromatography.