Table 1.

Central composite design (CCD) for the optimization of Yanang encapsulation

Treatment	Coded variablea			Process variableb
	X1	X2	X3	X1	X2	X3
1	−1	−1	−1	10	1:6	140
2	−1	−1	+1	10	1:6	160
3	−1	+1	−1	10	1:4	140
4	−1	+1	+1	10	1:4	160
5	+1	−1	−1	20	1:6	140
6	+1	−1	+1	20	1:6	160
7	+1	+1	−1	20	1:4	140
8	+1	+1	+1	20	1:4	160
9	0	0	0	15	1:5	150
10	0	0	0	15	1:5	150
11	0	0	0	15	1:5	150
12	0	0	0	15	1:5	150
13	−2	0	0	5	1:5	150
14	+2	0	0	25	1:5	150
15	0	−2	0	15	1:7	150
16	0	+2	0	15	1:3	150
17	0	0	−2	15	1:5	130
18	0	0	+2	15	1:5	170

^aCoded level of variables: + = upper level, − = lower level and 0 = center points

^bX₁, X₂ and X₃ were gum arabic concentration (%), the ratio of core material to wall material (w/w), and outlet temperature (°C), respectively.