Studies on the quality preservation of dried laver, "nori", Porphyra yezoensis. VIII. Influences of water activity and temperature on water sorption and pigment stability of toasted and dried laver, "Yaki-nori", Porphyra yezoensis.

ARAKI Shigeru, MA Jiahai, OGAWA Hiroo, OOHUSA Tuyosi, KAYAMA Mitsu

doi:10.2331/suisan.51.1109

Dried and toasted laver, “Yaki-nori”, Porphyra yezoensis, was compared with dried, but not toasted laver, “Hoshi-nori”, with respect to water sorption and the pigment stability during storage under various conditions.<br>The water-adsorbing activity of “Yaki-nori” was lower than that of “Hoshi-nori”, and hysteresis effect of the water adsorption profile was observed in “Yaki-nori”, but not in “Hoshinori”. During a three-day storage period at 20°C in 100% relative humidity, chlorophyll a was degraded mainly to chlorophyllide a and pheophorbide a in “Hoshi-nori”, but to pheophytin a in “Yaki-nori”, thus, suggesting that chlorophyllase, which hydrolyzes the chlorophyll and pheophytin to the chlorophyllide and pheophorbide respectively, was inactivated by the toasting process.<br>During a three-month storage period under various conditions of water activities and temperatures, chlorophyll a and carotenoids were degraded in similar profiles in “Yaki-nori”. However, the rate of pigment degradation in “Yaki-nori” depended more or less on the quality of the sample.

Studies on the quality preservation of dried laver, "nori", Porphyra yezoensis. VIII. Influences of water activity and temperature on water sorption and pigment stability of toasted and dried laver, "Yaki-nori", Porphyra yezoensis.

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