Abstract
Deterioration of oil and decomposition of tocopherol (Toc) in oil heated with or without an atuminum float were investigated. Some kinds of oil (soybean, hardend soybean, rapeseed, olive containing α-Toc and whale oil treated with the mixed Toc) were heated in glass tubes (2.7×20cm) at 180°C, and then the content of oxidized fatty acids (fatty substances insoluble in petroleum ether), anisidine, carbonyl and acid values, or amounts of Toc remaining in the oil were measured. The content of oxidized fatty acids, anisidine and carbonyl values of oil heated with the float were clearly lower than these of oil heated without the float, but the acid value for oil heated with the float was much higher. The degree of decomposition of Toc in oil without the float was much higher than that with the float. This result indicates that the decomposition of Toc in oil is not affected by the hydrolysate (free fatty acid) in oil, but by the thermal oxidation products (oxidized fatty acids and carbonyl composition etc.) in the oil.
