Authors: HAYDER KHALEEL QURBAN ALI, MOHAMMED ZULKALI MOHAMMED DAUD, ZINAH AL-AZZAWI
Abstract: An economic study was carried out to show the benefits of optimization during the production of citric acid from rice straw as a substrate by solid-state fermentation (SSF) using Aspergillus niger}. The optimization procedure for the media components (NH_4NO_3, KH_2PO_4, MgSO_4, CuSO_4, ZnSO_4, FeSO_4, and MnSO_4) was carried out using Plackett-Burman design (PBD) for the screening and central composite design (CCD) for the optimization. The results obtained from PBD indicated that NH_4NO_3, KH_2PO_4, and MgSO_4 were the most significant components that affected the citric acid production. The maximum yield obtained by CCD was 50.23 g citric acid/kg rice straw. The rate of citric acid production by SSF after the optimization indicated a profit of about 65% for SSF without any nutrient addition and of about 27% for SSF without optimization.
Keywords: Citric acid, solid-state fermentation, rice straw, Plackett-Burman design, central composite design
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