Table 2.

RSM central composite design of three parameters (real and coded values) of five levels and the experimental responses (TPC and inhibition % of DPPH) of IRAE from blood orange peels.

	Run	Ethanol (%) Real [Coded] Value	Time (h) Real [Coded] Value	Temperature (°C) Real [Coded] Value	TPC (g GAE/100 g DM)	Inhibition % of DPPH
Factorial Design	1	15 [−1]	0.5 [−1]	40 [−1]	0.95	34.75
	2	55 [+1]	0.5 [−1]	40 [−1]	1.22	36.06
	3	15 [−1]	1.5 [+1]	40 [−1]	1.12	47.54
	4	55 [+1]	1.5 [+1]	40 [−1]	1.30	42.95
	5	15 [−1]	0.5 [−1]	70 [+1]	1.18	42.79
	6	55 [+1]	0.5 [−1]	70 [+1]	1.79	54.10
	7	15 [−1]	1.5 [+1]	70 [+1]	1.19	44.26
	8	55 [+1]	1.5 [+1]	70 [+1]	1.60	56.39
Center Points	9	35 [0]	1 [0]	55 [0]	1.39	54.10
	10	35 [0]	1 [0]	55 [0]	1.47	55.90
	11	35 [0]	1 [0]	55 [0]	1.34	48.85
	12	35 [0]	1 [0]	55 [0]	1.50	52.95
	13	35 [0]	1 [0]	55 [0]	1.48	47.38
	14	35 [0]	1 [0]	55 [0]	1.48	52.62
Star Points	15	1.36 [−α]	1 [0]	55 [0]	1.17	39.34
	16	68.6 [+α]	1 [0]	55 [0]	1.52	45.74
	17	35 [0]	0.16 [−α]	55 [0]	1.27	46.39
	18	35 [0]	1.84 [+α]	55 [0]	1.34	51.64
	19	35 [0]	1 [0]	29.8 [−α]	1.21	36.39
	20	35 [0]	1 [0]	80.2 [+α]	1.90	55.57