Table 1.

Independent variables and their coded levels used for the optimization of loss mass substrate by the keratinolytic fungus

Factors	Independent variables	Range levels
		Low	Medium	High
		−1	0	+1
X1	pH	6.5	7.5	8.5
X2	Temperature (°C)	25	28	37
X3	Feathers (g)	0.5	1	2