Some studies on Citric acid production by Aspergillus niger

Abstract

The present study was undertaken to study Citric acid production by Aspergillus niger. Thirty different fungal infected Citrus fruits were taken from different areas of Pakistan. Aspergillus niger was isolated and then fungal growth was qualitatively tested to see weather or not the fungus produced Citric Acid. The best results came from an Orange taken from Islamabad which showed heavy precipitation when tested with Deniges reagent and rapid effervescence by the Carbonate test. Further tests were then conducted to study the effect of Inoculum size on the size of fungal pellets produced, their dry mass weight, and amount of Citric acid produced. The effect of Incubation period on Citric acid production was also studied. It was seen that the larger the size of the inoculum, the greater will be the dry mass weight of the pellets, and more citric acid will be produced. Whereas larger pellets are produced for smaller inoculum sizes. As a result of this study it was also seen that most citric acid is produced after longer incubation. periods, therefore showing a positive correlation between incubation time and amount of citric acid produced.