Factors influencing ultraviolet and electron beam irradiation-induced free radical damage of ascorbic acid

The oxidation of an unsaturated fatty acid and antioxidant vitamin by ultraviolet (UV) and electron beam (e− beam) irradiation was studied. Hydroxyl radical (OH), generated by Fe-EDTA and hemoglobin, under heat incubation or UV illumination, was compared. L-ascorbic acid (LAA; 10, 100 and 500 mM) oxidation was measured after irradiation at 0–10 kGy, in the presence and absence of myoglobin. Moreover, both UV and e− beam irradiation at 0–20 kGy were used to oxidize a linoleic acid emulsion, both with and without LAA. The presence of hemoglobin generated less OH, than Fe-EDTA under similar heating conditions. Generation of OH increased with illumination by UV. LAA was oxidized by e− beam irradiation, with an increasing rate of oxidation occurring at lower concentrations of LAA and higher dosages of irradiation. LAA (10 mM) exhibited pro-oxidant activity in the linoleic acid emulsion when exposed to both forms of irradiation, while 500 mM LAA exhibited antioxidant activity.