Abstract

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Citric acid production by Aspergillus niger isolated from spoilt beans using cane molasses was investigated. The spoilt bean on SDA media produced Aspergillus niger from which Citric acid was produced using submerged fermentation technique. The sensory properties of the Citric acid produced from A. niger indicated dark coloration with pH values of 3.55 as the minimum and 5.19 as the maximum. The total titrable acidity (TTA) in solid state fermentation by A. niger during Citric acid production was carried out, and the data obtained are mean values, with minimum value of 1.03 and maximum 2.55. Hence, the curve of TTA against the fermentation days showed that, as the fermentation day increases the volume of NaOH required to neutralize the acidity content in the fermentation medium also increases, but decreases at the 7th day. The concentration of Citric acid observed for the number of days of fermentation showed that the yield of the Citric acid increases with the number of days across the flasks, which have the minimum concentration value to be 0.05g/L at day 1, but different maximum values which are 0.24, 0.12, 0.13 and 0.12g/L at days 7, 5, 7 and 7 respectively. The microbial load in flasks 1, 2 and 4 were within the range of 10-19 cfu/g, while flask 3 showed an increase up to 38 cfu/g which is a significant increase compared to the other 3 flasks. The confirmatory test showed that flask 1, 2 and 4 produced Citric acid, while the flask 3 gave a negative result. This study showed that cane molasses is a suitable medium for biosynthesis of Citric acid by Aspergillis niger due to its nutritional content

Keywords: Aspergillus niger, cane molasses, Citric acid,