Production of Citric Acid from Garri Processing Solid Waste using Submerged Culture of Aspergillus niger

Background and Objective: Citric acid is a weak organic acid that occurs naturally in all citrus fruits. It is the largest consumed organic acid and is widely used in beverage, food and pharmaceutical industries. This study, therefore, investigates the efficient utilization of garri processing solid waste for citric acid production using Aspergillus niger in submerged culture. Materials and Methods: A series of experiments were designed on various fermentation parameters to establish the optimal conditions for citric acid production. Results: This study revealed that production parameters such as initial pH, incubation temperature and fermentation period had a profound effect on the amount of citric acid produced. Citric acid concentration, mycelium crude protein and biomass dry weight increased with initial pH of 5.5, time of 120 hrs, incubation temperature of 30°C and shaking condition of 200 rpm. Conclusion: The results revealed that the accumulation of biomass and mycelium crude protein has no significant effect on citric acid accumulation on garri processing waste by Aspergillus niger in submerged fermentation. The results of this study suggest that garri processing solid waste material could be harnessed for large-scale citric acid production.