Utilization of Pap processing waste in submerged culture of Aspergillus niger enriched with poultry dropping extract for citric acid production

Abstract

Determining the potential of pap processing waste for citric acid production was investigated using Aspergillus niger isolated from pap waste. The cost of substrate for citric acid production represents a significant percentage of the total production cost. The aim of this work was therefore, to utilize pap processing waste in submerged culture enriched with poultry dropping extract for citric acid production. The effect of initial pH, inoculums size, poultry dropping extract, pap processing waste concentration and alcohol addition were investigated on citric acid production from pap processing waste. The results show that the initial pH, inoculums size, poultry dropping extract, pap processing waste and methanol had significant effect on citric acid production from pap processing waste (p< 0.05). Citric acid concentration increased as the pH increased. A pH value of 6.0 was the optimum for maximum citric acid concentration of 6.5 ± 0.116 g/l after 96 hours of fermentation. Citric acid concentration also increased as the percentage inoculums increased. A 10 % inoculums size was the optimum with the maximum concentration of 8.0 ± 0.231 g/l citric acid. There is also an increase in citric acid concentration as the percentage poultry dropping extract concentrations increased from 5 % to 15 %. A 15 % poultry dropping extract concentrations was the optimum with the maximum concentration of 11.0 ± 0.251 g/l citric acid. As the concentration of the pap processing waste increased up to 20 % the citric acid concentration of 16.0 ± 0.413 g/l was produced after 96 hours of fermentation. A 3 % methanol addition was the optimum with the maximum citric acid concentration of 26.0 ± 0.351 g/l after 96 hours of fermentation. This research work has established the potential of pap processing waste on citric acid production if well harnessed.