Table 1.

Experimental matrix used for response surface methodology with experimental and predicted values for the independent variables, error rate, yield and final temperature after ultrasonic-assisted extraction of J. spicigera leaf extracts

Run	Predictors1			Response variable		Error rate (%)	Yield (%)	Final temperature (°C)
	XPC (s)	XSA (%)	XET (min)	Experimental SP2	Predicted SP3
1	0.4	40	7	23.89 ± 2.16d	23.91	− 0.08	4.65	20 ± 0.5
2	1	40	7	25.43 ± 0.42cd	25.37	0.23	5.08	24 ± 0.5
3	0.4	100	7	24.47 ± 0.79d	23.85	2.53	4.78	24 ± 0.5
4	1	100	7	25.87 ± 0.20d	23.20	10.32	4.74	26 ± 0.5
5	0.4	70	2	24.55 ± 1.05cd	24.27	− 0.08	4.91	19 ± 0.5
6	1	70	2	32.60 ± 0.90b	32.88	− 0.08	6.52	20 ± 0.5
7	0.4	70	12	25.21 ± 0.96cd	24.93	1.11	5.04	23 ± 0.5
8	1	70	12	23.98 ± 0.21d	24.26	− 1.16	4.79	27 ± 0.5
9	0.7	40	2	37.12 ± 0.70a	36.85	0.72	7.42	20 ± 0.5
10	0.7	100	2	27.19 ± 0.56c	27.47	− 1.02	5.43	24 ± 0.5
11	0.7	40	12	24.51 ± 1.48cd	24.23	1.14	4.90	21 ± 0.5
12	0.7	100	12	24.42 ± 0.12cd	24.70	− 1.14	4.88	26 ± 0.5
13	0.7	70	7	33.44 ± 0.74b	33.85	− 1.12	6.68	20 ± 0.5
14	0.7	70	7	33.87 ± 0.76b	33.85	0.05	6.77	20 ± 0.5
15	0.7	70	7	34.24 ± 0.18b	33.85	1.13	6.85	20 ± 0.5

All values are mean ± SD of three determinations by triplicate (n = 9). Different letters in each file indicate significant statistical differences between treatments (α = 0.01)

¹Pulses cycle (X_PC); Sonication Amplitude (X_SA) and Extraction Time (X_ET)

²Gallic acid equivalents (mg GAE/g dry basis)

³The values were predicted using a secondary polynomial equation, R² = 0.97. Gallic acid equivalents (mg GAE/g dry basis)