The accumulation of peroxides, acid values, and carbonyl values during irradiation and post-irradiation storage of the ricebran oil has been studied. The rice bran oils were irradiated two doses of 2 and 7 megarads (300 rads/sec) at 23℃ atmospheric circumstance. The acid values, peroxide values and carbonyl values were measured at regular intervals of one week during the stroage at 5° and 25°.
1) During the storage, the acid values of the irradiated rice bran oils increased or decreased insignificantly regardless of the addition of antioxidants and storage temperature.
2) The peroxide values were not increased continuously but increased zigzag.
The result was indicated that the composition and decomposition of peroxides occurred continuously throughout the storage.
3) As the peroxide values increased, carbonyl values decreased and changed quite differently, but, especially in 7th week, they were constant or insignificant.
4) Bibutylhydroxytoluene is more effective than cafieic acid in retarding the formation of peroxides during irradiation of rice bran oils and post-irradiation storage. The effect of antioxidant is more efficient at 2 megarads than at 7 megarads irradiation. When we store the rice bran oil, the addition of antioxidants of post-irradiation is more desirable than that of preirradiation.
5) In spite of changing conditions such as storage ternperature and addition of antioxidants, the peroxide values of rice bran oils irradiated at 2 megarads were always greater than those at 7 megarads during tha storage. Peroxide oalues of samples at high temperature (25℃) storage increased as twice as those of low temperature (5℃) storage samples. At low temperature, peroxide values in the first week increased twice during the period of 8th weeks storage, but those did from three to four times at higher temperature in the same period Therefore, the low temperature storage is recommandable too.
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