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QUENCHING MECHANISMS AND KINETICS OF CAROTENOIDS IN RIBOFLAVIN PHOTOSENSITIZED SINGLET OXYGEN OXIDATION OF VITAMIN D 2
Author(s) -
LI TSUNGLIN,
KING JOAN M.,
MIN DAVID B.
Publication year - 2000
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.2000.tb00717.x
Subject(s) - singlet oxygen , chemistry , retinyl acetate , reaction rate constant , photochemistry , riboflavin , quenching (fluorescence) , oxygen , vitamin , kinetics , retinol , organic chemistry , biochemistry , fluorescence , physics , quantum mechanics
The oxidation of vitamin D 2 in a solution of 12% water, 88% acetone and 15 ppm ribqflavin under light or dark was studied by measuring the headspace oxygen. Ribofiavin accelerated the oxidation of vitamin D 2 by singlet oxygen under light, but did not affect vitamin D 2 oxidation under dark. Quenching mechanisms and kinetics within the range of 0–20 ppm β‐cawtene or fucoxanthin and with 0–80 ppm retinyl acetate or retinol on 15 ppm riboflavin photosensitized singlet oxygen oxidation of vitamin D 2 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 D 2 with singlet oxygen was 2.2 times 10 7 M −1A s −1 . The carotenoids minimized the oxidation of vitamin D 2 by quenching singlet oxygen. The total quenching rate constants of retinol, retinyl acetate, jucoxanthin and ft‐carotene were in the order of 1.22 times 10 8 , 5.98 times 10 8 , 1.78 times 10 9 and 5.00 times 10 9 M −1 . s −1 respectively, which suggests that as the number of double bonds of carotenoids increases, the quenching rate constant ofcarotenoid increases.