Phycoerythrin Contributes to the Photooxidation of Eicosapentaenoic Acid in Porphyra yezoensis During Light Exposure

• Autores: Tatsuya Sugawara, Yukako Komura, Hiroshi Hagino, Takashi Hirata
• Localización: Journal of food science, ISSN 0022-1147, Vol. 71, Nº 6, 2006
• Idioma: inglés
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• Resumen

  • Porphyra yezoensis, a red alga, is widely consumed as a familiar daily food in Japan. Lipid oxidation products including volatile decompositions during drying process might contribute to the quality and flavor of dried nori prepared from P. yezoensis. To explore the mechanism of photooxidation in the alga during light exposure, we investigated the contribution of phycoerythrin to eicosapentaenoic acid (EPA) photooxidation in P. yezoensis. After EPA dispersed in aqueous solution in the presence of Tween 20 was incubated with phycoerythrin under light-exposed condition, the 6- and 17-isomers of methyl trimethylsiloxy eicosanoate derived from 6- and 17-hydroperoxy EPA, respectively, the specific hydroperoxide isomers by photosensitized oxidation, were detected by gas chromatography–mass spectrometry analysis. After the light exposure for 15 h at 4 °C, the generation of 6-hydroperoxy EPA in P. yezoensis was 2 times higher than in a fresh alga. Moreover, 17-isomer production by light exposure was almost 14 times higher than in nontreated control. After exposing to filtered light passed through a band-pass-type filter that can transmit 60% of light of maximum wavelength at 550 nm for partial excitation of phycoerythrin, each amount of 6- and 17-isomer (approximately 80% and 25% of that exposed by nonfiltered light) was higher than in a fresh alga. These results suggested that phycoerythrin might, at least in part, contribute to the generation of singlet oxygen and the photooxidation of lipid in P. yezoensis during light exposure. The content of phycoerythrin would be important for the quality of color, flavor, nutrition, and biological functions in P. yezoensis.