Table 1.

Experimental range and levels of the three independent variables used in RSM in terms of actual and coded factors

S.No	Variables	Range and levels
		− 1	0	+ 1
1.	pH	4	5.5	7
2.	Temp	25	32.5	40
3.	Casein conc.	0.5	2.75	5

– 1, minimum value; 0, average value; + 1: maximum value