各種水分活性下における乾のり中の色素成分の変化〔乾のりの品質保持に関する研究-2-〕

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Degradation of four pigments; phycoerythrin, phycocyanin, chlorophyll a, and carotenoids, was studied as a function of water activity (in the range of 0 to 0.6) during storage of dried laver "Nori" Porphyra yezoensis for six months at 15-18°C. The extract of chlorophyll a and its decomposed compounds were fractionated into three components;chilorophyll a, phaeophytin a, and phaeophordide a-like substances by means of ion exchange column chromatography. The last one contained a substance which appeared similar to phaeophytin a in its absorption spectra, but was probably absent in phytyl residue. Chlorophyll a was very stable in the aw range of 0 to 0.2, but it began ot degrade at aw higher than 0.3. The rate increased with increasing of aw. The degradation of chlorophyll a was accompanied by the formation of phaeophytin a and phaeophorbide a- like substances. The amount of phaeophorbide a-like substances produced was 2 to 3 times as much as that of phaeophytin a. It seemed that carotenoids might be destroyed at extremely dry conditions, such as aw 0, and most of them were also destroyed at aw higher than 0.3. Phycoerythrin and phycocyanin were the most stable pigments, since only 10% were destroyed even at aw 0.6. These results suggest that the color of "Nori" can be preserved most safely at aw 0.1, which corresponds to the BET monolayer coverage.
日本水産學會の論文