Optimization of Essential Oil Extraction from Bitter Leaf (Vernonia Amygdalina) by Using an Ultrasonic Method and Response Surface Methodology

Table 2

The design matrix of BBD and yield of essential oil.

Run number	Independent variables			Response
	A: sonication time (min)	B: ultrasonic power (W)	C: liquid-solid ratio (ml/g)	Y: yield of essential oil % (g/g)
1	20	200	8	4.085
2	20	150	6	4.121
3	20	150	6	4.114
4	20	150	6	4.102
5	10	200	6	3.631
6	20	100	8	3.673
7	10	100	6	3.193
8	30	150	4	2.96
9	30	200	6	3.45
10	20	150	6	4.053
11	10	150	4	2.704
12	30	150	8	3.42
13	20	150	6	4.088
14	20	200	4	3.013
15	20	100	4	3.045
16	30	100	6	3.289
17	10	150	8	3.98