Abstract:

Chirocephalus diaphanous eggshell was ground, defatted and sieved before being subjected to ultrasonic-assisted
extraction with 60% ethanol solution as the solvent to obtain pigment. The structure of the pigment as well as its maximum
absorption peak was determined by infrared and ultraviolet-visible spectroscopy. Then effects of light, temperature, pH,
food additives, metal ions, oxidant and reductant on its stability were investigated. Total antioxidant capacity and hydroxyl
and ABTS radical scavenging activities of the pigment were measured by in vitro. The results showed that the pigment
was a dark brown powder composed of amide-aromatic compounds with –OH, –CH2–, –C≡C– and –C–O–C–, and the
maximum absorption peak appeared at 397 nm. The pigment was sensitive to outdoor natural light, ultraviolet light and
high temperature. pH, sacrose, sodium carbonate, sodium bicarbonate, sodium citrate, Na+ and K+ could affect the stability
of the pigment. Acidic environment, citric acid, tartaric acid, soluble starch, Mg2+ and Al3+ had a hyperchromic effect on the
pigment. However, sodium benzoate, Ca2+, Zn2+, Fe3+, Fe2+, Cu2+ and Pb2+ could destroy the pigment in different degrees. The
pigment could be easily damaged by oxidant, but it had high capacity to resist reduction. The pigment possessed favorable
total antioxidant activity, and its IC50 for scavenging hydroxyl and ABTS radicals were 6.104 and 0.377 mg/mL, respectively.
Therefore, the pigment can be used as a natural antioxidant.

Key words: Chirocephalus diaphanous eggshell, pigment, stability, in vitro antioxidant activity