Orange Peels Valorization For Citric Acid Production Through Single And Co-Culture Fermentation.

The present work describes fermentation of raw materials to produce citric acid through single and co-culture process using indigenous strains of Aspergillus niger and Aspergillus fumigatus. For this purpose, orange peels, peanut shells and their homogenous mixtures were used as raw material using solid state fermentation (SSF). Incubation period, pH, temperature, moisture content, inoculum size and substrate concentrations were optimized simultaneously using response surface methodology (RSM) design followed by contour plot analysis. Citric acid was separated from other by products in a nonpolar C-8 column and quantified using reversed phase high performance liquid chromatography (RP-HPLC) technique. It was found that more amount of citric acid (114.68±0.73 mg/mL) was produced during co-culture fermentation employing both A. niger and A. fumigatus simultaneously as compared to single culture fermentation inoculated with A. niger (94.92±0.46 mg/mL) and A. fumigatus (65.13±0.28 mg/mL), using 25 gms orange peels OPs as substrate, 60 % moisture content, 6 pH, 6 mL inoculum size, 6 days incubation period and 50 °C temperature as optimized fermentation conditions. The results also showed that RSM based co-culture SSF using cheap biomass can produce more amount of citric acid as compared to conventional fermentation. [ABSTRACT FROM AUTHOR]