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. 2021 May 31;63(3):603–613. doi: 10.5187/jast.2021.e43

Table 1. Factors and their levels in our central composite design (CCD).

Actual factor (Coded factor) Actual factor level corresponding to the coded factor level
2.366 −1 0 1 2.366
Peptone soy (X1) (% [w/v]) 0.000 1.155 2.000 2.845 4.000
Yeast extract (X2) (% [w/v]) 0.000 1.155 2.000 2.845 4.000
Glucose (X3) (% [w/v]) 0.000 0.577 1.000 1.423 2.000
L-cystein (X4) (% [w/v]) 0.000 0.289 0.500 0.711 0.100
Ferrous sulfate (X5) (% [w/v]) 0.000 0.006 0.010 0.014 0.020