Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Food Technology


The decomposition of fatty acid hydroperoxides leads to the formation of various carbonyl compounds in different yields. A method for the quantification of carbonyl compounds in oxidized fat by gas chromatography of the trichlorophenylhydrazones was adapted for the quantification of carbonyls produced from the decomposition of pure linoleic acid and linolenic acid hydroperoxides produced by autoxidation or enzymatically by soybean lipoxygenase or potato lipoxygenase. The hydroperoxides were dissolved in dodecane and decomposed anaerobically under different conditions: temperature, metal ions, and antioxidants;Both linoleic acid 9- and 13-hydroperoxides produced hexanal and 2,4-decadienal at higher temperatures (80(DEGREES)C, 160(DEGREES)C), but only hexanal was formed under milder temperatures (40(DEGREES), 55(DEGREES)C) in yields varying from 5% to 12%. Metal ions (Cu('++), Fe('++)) and antioxidants Propyl Gallate (PG), Butylated Hydroxy Anisole, Butylated Hydroxy Toluene (BHT), (alpha)-Tocopherol ((alpha)-Toco.), and Tertiary Butylated Hydroxy Quinone (TBHQ) accelerated hydroperoxide decomposition resulting in higher yields of carbonyls in the case of metal ions and lower yields in the presence of antioxidants. Most of the carbonyls formed from the decomposition of methyl linoleate, and methyl linolenate hydroperoxides were those expected from the scission of monohydroperoxides at the two sides of their alkoxy radicals. Their molar yields were from 1% to 8% for methyl linoleate hydroperoxides and from 1% to 4% for methyl linolenate hydroperoxides;Linolenic acid 13-hydroperoxide formed 2- or 3-hexenal (3%) and 2-pentenal (2.5%) at high temperature (160(DEGREES)C), but only 2-pentenal at 55(DEGREES)C. However, the 9-isomer did not produce any quantifiable carbonyls under the conditions investigated.



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Bouali Saaidia



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81 pages