Table 5.

Predicted and experimental values of the responses at optimum conditions for ultrasound- assisted and conventional extraction methods.

Extraction method	Astaxanthin content	DPPHsc	FRAP
Extraction method	(µg/g)	(%)	(µmol Fe²⁺/kg)
Solvent extraction (petroleum ether/acetone/water Solvent; 15:75:10)
Experimental values¹	48.47 ± 0.35^b^*	67.64 ± 0.71^b	1504.90 ± 16.39^b
Ultrasound-assisted extraction (UAE)
Optimized values²	51.47^a	73.89^a	1704.71^a
Experimental values ¹	50.78 ± 0.15^a	72.0 ± 0.48^a	1689.90 ± 17.85^a

The data within a column with the same letters are not significantly different at p < 0.05.

Mean ± standard deviation of triplicate determinations from experiments.

Predicted using response surface quadratic model.