ABSTRACT

Citric acid holds considerable economic value and finds diverse applications across various industries. Some agricultural and industrial byproducts, such as yam peels, cocoyam peels, and pineapple peels are utilized in the production of citric acid. This research aims to optimize the influence of inducers necessary to maximize citric acid production from a three-component feedstock using Aspergillus niger. Mixture and Response Surface designs were employed to investigate the impact of the composite feedstock and inducers (specifically tween20, tween80, and triton X-100) on citric acid production with Aspergillus niger. The optimization process was conducted using Response Surface Methodology (RSM), which yielded a quadratic model for predicting citric acid concentration based on the composite feedstock and inducers.

The optimal composition of the three-substrate feedstock, as determined by the mixture design, consisted of 9.435g of yam peel, 3.801g of cocoyam peel, and 1.765g of pineapple peel, resulting in a maximum citric acid yield of 32.351g/1. The performance of these models was assessed using Ra and Root Mean Square Error (RMSE). The optimization studies demonstrated that the highest citric acid yield achieved was 32.351g/1 using RSM. The inducers played a significant role in enhancing citric acid production, with the maximum yield reaching a concentration of 39.514ml. The optimal levels of the factors were found to be 1.962% w/w for tween20, 0.188% w/w for tween80 and 1.854% w/w for triton X-100. In conclusion, inducers were found to have a substantial impact on citric acid production, making them highly recommendable, especially in situations where sources of agro-waste substrates for citric acid production are limited.