Fermentation of the fruit pulp of Dialium guineense (Velvet tamarind) for Citric Acid Production Using Naturally Occurring Fungi
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Date
2015
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Abstract
The aim of this research was to produce citric acid from the fruit pulp of Dialium
guineense using naturally occurring fungi in a solid state fermentation. The fruit
pulp was de-capped from the seed and dried at 60
oC in an oven. Natural
fermentation was carried out for seven days at 28
0C ± 2. The fungi were isolated
and identified as Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Penicillium citrinum, Mucor hiemalis, Mucor racemosus, Rhizopus stolonifer, Alternaria tenuis Syncephalastrum racemosus, Saccharomyces cerevisiae and
Schizosaccharomyces pombe. They were screened for citric acid production using
standard methods. Yellow coloration confirmed citric acid production after five
days of incubation. Organisms that were strongly positive for citric acid production
include Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Penicillium citrinum, Mucor racemosus, and Alternaria tenuris. They were used to
ferment the fruit pulp of D. guineense in a solid state fermentation by inoculating
2ml spore suspension of 2x10
5 spores/ml of each of the isolates on separate
Erlenmeyer flasks of 250ml for seven days at 28 ± 2
oC. Quantitative production of
citric acid was determined using standard methods. Aspergillus niger had the
highest citric acid production of 14.07mg/g while Aspergillus flavus had the lowest
citric acid production of 6.34mg/g. The result of this investigation reveals that
some of the naturally occurring fungal isolates from the natural fermentation of the
fruit pulp of D. guineense are capable of utilizing the substrate for the production
of citric acid and could be employed for the production of citric acid on large scale.