Evaluating the potential of wild cocoyam (Caladium bicolor) for citric acid production in a submerged culture of Aspergillus niger.

Background: Wild cocoyam (Caladium bicolar) is non-edible starchy material which is commonly known as 'Ede umuagbara' in the south-east region of Nigeria. Evaluating the potential of wild cocoyam for citric acid production was investigated using Aspergillus niger in a submerged culture. Results: This study showed that wild cocoyam flour concentration, pretreatment of wild cocoyam, inoculums size, initial pH of wild cocoyam and incubation temperature of wild cocoyam medium had significant effect on the amount of citric acid produced from wild cocoyam (p < 0.05). Citric acid concentration increased as the concentration wild cocoyam increased up to 15% with the maximum citric acid concentration of 10.0 ± 0.251 g/l after 96 h of fermentation. Also citric acid concentration increased as the pretreatment time of wild cocoyam increased from 5 to 20 min. A 20 min pretreatment time at 121 °C was the optimum with maximum concentration of 14.0 ± 0.325 g/l citric acid after 96 h of fermentation. 15% inoculums was the optimum with the maximum concentration of 16.0 ± 0.431 g/l citric acid. However, the wild cocoyam initial pH value of 5.5 was the optimum for maximum citric acid concentration of 19.0 ± 0.316 after 96 h of fermentation. Moreover, citric acid concentration increased as the incubation temperature of wild cocoyam medium increased from 20 to 30 °C. Incubation of wild cocoyam medium at 30 °C was the optimum with the maximum citric acid concentration of 23.0 ± 0.432 g/l after 96 h of fermentation. Conclusion: Therefore, the result revealed that wild cocoyam which is found plenty within the south-east region of Nigeria can be converted to citric acid if well harnessed. [ABSTRACT FROM AUTHOR]