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Oxidation mechanism of riboflavin destruction and antioxidant mechanism of tocotrienols

Kim, Hyun Jung
http://rave.ohiolink.edu/etdc/view?acc_num=osu1184681773

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Food Science and Nutrition.
Riboflavin is a photosensitizer to produce singlet oxygen. The compound formed from riboflavin under light was positively identified as 2,3-butanedione by a combination of gas chromatographic retention time, mass spectrum and odor evaluation of authentic 2,3-butanedione. The addition of sodium azide, a singlet oxygen quencher, minimized the formation of 2,3-butanedione from riboflavin. The 2,3-butanedione was formed from the reaction between riboflavin and singlet oxygen. The effects of 0, 100, 200, 300, 500, and 1000 ppm of alpha-, beta-, gamma-, and delta-tocotrienol on the oxidation of lard in the dark at 55°C for 7 days were determined by measuring headspace oxygen and peroxide value. The 100 ppm alpha- or beta-tocotrienol was the most effective antioxidant. Gamma- or delta-tocotrienol at all concentrations significantly lowered the oxidation of lard. The antioxidative activities were in delta- > gamma- > beta- > alpha-tocotrienol. The selection of type and optimum concentration of tocotrienol can minimize the oxidation of lipids and be economically important. Samples of 0.1, 0.25, or 0.4 M lard in methylene chloride containing 4.4 × 10 -6M chlorophyll b and 0, 0.3, 0.6, or 0.9 mM alpha-, beta-, gamma-, or delta-tocotrienol were prepared and stored at 3,000 lux for 4 hours to study the quenching mechanisms of tocotrienols on the chlorophyll photosensitized oxidation of lard. The steady state kinetic study showed that tocotrienols acted as singlet oxygen quenchers. The reaction rate of singlet oxygen with lard was 6.5 × 10 4M -1sec -1. The singlet oxygen quenching rates of alpha-, beta-, gamma-, and delta-tocotrienol were 2.16 × 10 7, 1.99 × 10 7, 2.05 × 10 7, and 0.80 × 10 7M -1sec -1, respectively. Alpha-tocopherol in foods is oxidized during the processing and storage. The effects of 0, 250, 500, 1000 and 1500 ppm of oxidized alpha-tocopherol on the oxidation of purified soybean oil in the dark at 55°C for 6 days were studied. The oxidized alpha-tocopherol acted as prooxidant. The prooxidant mechanism may be due to intermediate compounds such as hydroxyl, peroxy or oxy radical and singlet oxygen formed during the oxidation of alpha-tocopherol. The prevention of tocopherol oxidation and removal of oxidized tocopherol could improve the oxidation of foods.
David Min (Advisor)
175 p.
Riboflavin; Singlet Oxygen; 2; 3-Butanedione; Tocotrienol; Antioxidant; Singlet Oxygen Quencher; Oxidized Tocopherol; Prooxidant

Recommended Citations

Citations

  • Kim, H. J. (2007). Oxidation mechanism of riboflavin destruction and antioxidant mechanism of tocotrienols [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1184681773

    APA Style (7th edition)

  • Kim, Hyun Jung. Oxidation mechanism of riboflavin destruction and antioxidant mechanism of tocotrienols. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1184681773.

    MLA Style (8th edition)

  • Kim, Hyun Jung. "Oxidation mechanism of riboflavin destruction and antioxidant mechanism of tocotrienols." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1184681773

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.