Fig. 1. Ultraviolet-visible absorption spectra of the yolk extract and canthaxanthin
a, b, c are the first, second and third yolk extracts respectively; d, e and f are the standard solution of canthaxanthin with concentrations of 1, 10 and 20 μg·mL^-1, respectively

Fig. 2. The first derivative spectra of yolk extract and canthaxanthin
a, b, c are the first, second and third yolk extracts respectively; d, e and f are the standard solution of canthaxanthin with concentrations of 1, 10 and 20 μg·mL^-1, respectively

Fig. 3. (a) is the ultraviolet-visible absorption spectrum of the yolk extract with canthaxanthin; (b) is the first order derivative spectrum of (a)
g, h, i, j, k, l and m represent canthaxanthin with the concentrations of 0, 2.67, 5.33, 8.00, 10.67, 13.10 and 17.68μg·mL^-1, respectively

Fig. 4. Standard curve (a) and linear regression equation of canthaxanthin (b) in egg yolk extract