Date of Award

12-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Food Science

First Advisor

Prof. Afaf Kamal-E ldin

Second Advisor

Dr. Ismeldin Bashir Hashim

Third Advisor

Dr. S. Salman Ashraf

Abstract

During the oxidation of bulk oils, oxidation products (i.e. peroxide values, conjugated dienes and thiobarbituric acid reactive substances) are formed gradually and increased sharply at the end of the induction period. Tocophero1s were consumed, some water was formed, and micelles increased in size during the induction period of vegetable oils oxidized in bulk. The evidence that the evolution of micellar size was in parallel with the end of induction period corroborates the recognition that micelles are the active site of oxidation. The interaction of α-tocophero1 and three synergists: ascorby1 palmitate, phosphatidy1choline and L-lysine were studied in cod liver oil, to examine their effects on formation of thiobarbituric acid reactive substances. Second order polynomial models were found to satisfactorily represent the slope of changes of conjugated dienes, thiobarbituric acid reactive substances and α-tocopherol during the induction period. The suggested optimized levels of the four additives to protect cod liver oil at 30°C based on the rate of thiobarbituric acid reactive substances formation and loss of α-tocopherol (day 0 to 4) are α-tocopherol (1200 μg/g), ascorby1 palmitate (100 μg/g), phosphatidy1choline at (9000 μg/g), and L-lysine (1000 μg/g). Higher level of α-tocopherol and ascorby1 palmitate did not give better protections to the oils or caused a loss in the antioxidant efficacy, compared to when the additives were added at lower levels. Phosphatidy1choline was effective at a wide range of high concentration while L-lysine improved the protection at levels up to 4000 μg/g.

Included in

Food Science Commons

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