Abstract
Author contemplated to survey the change of carbonyls occurring in the soybean oil at the frying temperature (190°C). The column and thin layer chromatographic methods were employed for separation and identification of the carbonyls.
I. The results of frying test were : 1) Before the TSUKARE (weariness of oil) appeared, the major portions of carbonyls were C4, C6 and C10C12 and when the TSUKARE developed, C3, C5 and C7 appeared in the oil. But these mono-carbonyls constituted only 2030% of the total and the remainder were higher carbonyls formed inside glyceride (or polymerized glyceride). 2) At the earlier stage of oxidation, the amount of staturated carbonyls was significantly larger than the unsaturated, but as oxidation developed, the unsaturated content increased in the oil according with progress.
II. The results of aeration test were : 1) With the progress of oxidation, the unsaturated carbonyls (C3C7) increased in both scattered out of the oil and remained in the oil. But there seemed that the saturated were enriched in the former and the unsaturated condensed in the latter. 2) The scattered carbonyls consisted of 1623% of the total, and considerable amount of volatile carbonyls (2028%) was detected in the oil. 3) As to the oxidation mechanism for the formation of carbonyl group at the frying temperature, it could be conceived that the carbonyl formation inside the oxidative glyceride is unremittingly competing with the fission reaction of carbon to carbon bond in the oil, and with increase in the TSUKARE, the fission occurres more frequently than the carbonyl-glyceride formation.
