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

The oxidation of an unsaturated fatty acid and antioxidant vitamin by ultra violet (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 LA A. The presence of hemoglobin generated less . OH, than Fe-EDTA under simil ar heating conditions. Generation of . OH increased with illumination by UV . LAA was oxidized by e(-) beam irradiation, with an increasing rate of oxi dation occurring at lower concentrations of LAA and higher dosages of irrad iation. LAA (10 mM) exhibited pro-oxidant activity in the linoleic acid emu lsion when exposed to both forms of irradiation, while 500 mM LAA exhibited antioxidant activity. (C) 2001 Elsevier Science Ltd. All rights reserved.