TABLE 1.

Levels of independent variables in RSM for riboflavin production.

Variables	Factors	Lower factorial point (−1)	Central point (0)	Upper factorial point (+1)
A	Glucose (g/L)	10	15	20
B	Yeast extract (g/L)	10	15	20
C	pH	5	6	7
D	Temperature (°C)	30	40	50