Table 2.

Coded and actual values used in the central composite rotatable design (CCRD) for reducing foodborne pathogens inoculated in apple juice

Variables	Code	− 1.68	− 1	0	+ 1	+ 1.68
Pressure (MPa)	x1	100	201	350	499	600
Holding time (s)	x2	26	60	110	160	194
DMDC (mg/L)	x3	116	143	183	223	250

− 1.68 (lower axial point), − 1 (lower level), 0 (central point), + 1 (upper level), + 1.68 (upper axial point)

α = (2ⁿ)^1/4 = 1.68 where n is the number of variables