Quenching mechanisms and kinetics of carotenoids in riboflavin photosensitized singlet oxygen oxidation of vitamin D2

Document Type

Article

Publication Date

1-1-2000

Abstract

The oxidation of vitamin D2 in a solution of 12% water, 88% acetone and 15 ppm riboflavin under light or dark was studied by measuring the headspace oxygen. Riboflavin accelerated the oxidation of vitamin D2 by singlet oxygen under light, but did not affect vitamin D2 oxidation under dark. Quenching mechanisms and kinetics within the range of 0-20 ppm β-carotene or fucoxanthin and with 0-80 ppm retinyl acetate or retinal on 15 ppm riboflavin photosensitized singlet oxygen oxidation of vitamin D2 were also studied. The rate of singlet oxygen formation by 15 ppm riboflavin was 1.78 umole oxygen/mL headspace-hour. The reaction rate constant of vitamin D2 with singlet oxygen was 2.2 × 107 M-1 s-1. The carotenoids minimized the oxidation of vitamin D2 by quenching singlet oxygen. The total quenching rate constants of retinal, retinyl acetate, fucoxanthin and β-carotene were in the order of 1.22 × 108, 5.98 × 108, 1.78 × 109 and 5.00 × 109 M-1, s-1 respectively, which suggests that as the number of double bonds of carotenoids increases, the quenching rate constant of carotenoid increases.

Publication Source (Journal or Book title)

Journal of Food Biochemistry

First Page

477

Last Page

492

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