Abstract :

Optimization of citric acid production by Aspergillus niger isolated from soil was studied by solid state fermentation with Coffee husk (CH) and Lemon Peel Pomace (LPP). Box?Behnken design (BBD) was used to optimize the variables such as pH, incubation time, coffee husk and lemon peel pomace. The BBD design analysis showed a reasonable adjustment of the quadratic model with the experimental data. A statistical model predicted the highest citric acid concentration as 103 g/kg, at the optimal condition pH 5.0, 120 hrs, CH 6% with 10% of LPP. The 3-D plots were generated to evaluate the changes in the response surface and to understand the relationship between the citric acid yield and the culture conditions