Table 1.

The experimental conditions of CO₂ supercritical fluid extraction (CO₂-SFE) and yield of Rana chensinensis ovum oil (RCOO) based on the Box–Behnken Design (BBD).

No.	X1: Pressure (MPa)	X2: Flow (L/h)	X3: Temperature (°C)	X4: Time (min)	Actual Yield (%)	Predicted Yield (%)	Residual (%)
SFE1	35	75	47	30	8.69	8.05	0.64
SFE2	25	75	47	90	11.48	11.31	0.17
SFE3	35	100	47	90	11.92	12.19	−0.27
SFE4	25	100	32	90	11.99	11.36	0.63
SFE5	15	100	47	90	9.08	10.09	−1.01
SFE6	25	100	62	90	11.69	10.61	1.08
SFE7	25	50	47	150	11.51	11.12	0.39
SFE8	35	75	32	90	10.16	9.65	0.51
SFE9	25	75	32	30	3.81	5.20	−1.39
SFE10	35	75	47	150	13.06	13.42	−0.36
SFE11	15	75	47	30	3.03	1.92	1.11
SFE12	25	50	62	90	7.55	7.42	0.13
SFE13	25	75	47	90	11.55	11.31	0.24
SFE14	25	75	62	150	12.56	12.20	0.36
SFE15	25	50	47	30	2.36	1.77	0.59
SFE16	25	100	47	30	7.96	8.07	−0.11
SFE17	15	75	47	150	10.65	10.53	0.12
SFE18	25	75	47	90	10.89	11.31	−0.42
SFE19	15	75	32	90	9.24	8.48	0.76
SFE20	25	75	32	150	11.25	11.44	−0.19
SFE21	25	100	47	150	12.39	12.71	−0.32
SFE22	25	75	62	30	3.61	4.46	−0.85
SFE23	35	50	47	90	10.62	10.65	−0.03
SFE24	15	50	47	90	2.98	3.74	−0.76
SFE25	35	75	62	90	12.51	13.00	−0.49
SFE26	15	75	62	90	4.93	5.16	−0.23
SFE27	25	50	32	90	6.32	6.65	−0.33

X₁, X₂, X₃, and X₄ are the codes for pressure, flow, temperature, and time in the BBD model, respectively.