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Summary The stability of polyhydroxylated 1,4‐naphthoquinone pigment recovered from sea urchin ( Strongylocentrotus nudus ) spines was observed by spectrophotometer. When pH values changed from 2.0 to 10.0, the pigment showed colour variations. Meanwhile, pH values affected the stability of the pigment. After 24 h of storage, the pigment remained 95.64%, 79.68% and 46.15% of the initial absorbance at pH 3.0, 7.0 and 10.0, respectively. The pigment was prone to degrade on exposure to light. It remained 40.11% of the initial absorbance under natural light after 14 days of storage. Whereas the corresponding value in the dark was 65.14%. Degradation rate of the pigment increased with increasing temperature. The pigment remained 90.49% of the initial absorbance at 20 °C after 24 h of storage. However, the corresponding value decreased to 66.61% at 80 °C. Additives, including antioxidant, oxidising and reducing agents, and some metal ions all affected the stability of the pigment.
Zhou et al. (Fri,) studied this question.