Residual quantity of a-tocopherol, BHA and BHT added to oils was examined after purification and hydrogenation processes, and the following results were obtained.
1) α-Tocopherol, BHA and BHT concentration in the oil hardly changed after deacidification, but a large amount of sodium hydroxide slightly reduced the amount of a -tocopherol.
2) α-Tocopherol, BHA and BHT concentration in the oil decreased slightly by use of activated clay for decolorization, and the rate of reduction of BHA and BHT was smaller than a-tocopherol. Use of an adsorbent containing activated carbon increased the reduction rate to a slight extent.
3) BHA and BHT were completely removed from the oil even by treatment at 160°C, the temperature lower than that used for usual deodorization treatment, but 50% of α-tocopherol remained even by treatment at 250°C, althought the decrease became greater at higher temperatures of deodorization treatment.
4) Change in the concentration of α-tocopherol by hydrogenation of the oil depended on the kind of catalyst used, and a-tocopherol concentration decreased in the order of Ni, Ni-Cu, Pd-C, and Cu-Cr catalyst. By the use of a Ni catalyst, concentration of α-tocopherol hardly changed when hydrogenated at an atomospheric pressure, irrespective of temperature, but under a high-pressure, the rate of decrease became greater with increasing temperature. In contrast, concentration of BHA and BHT decreased markedly by the use of Cu-Cr or Cu-Ni catalyst at atomospheric pressure, but the decrease was small under other conditions.
