Production of citric acid from pineapple waste using aspergillus niger

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The need to recycle waste materials should be paramount in our country since these materials are becoming environmental hazard. One such method by which the waste material could be recycled is through biotechnology. Pineapple peels, one of such waste materials that contribute to the environmental degradation of our towns and cities were collected, mashed and the juice extracted was utilized for citric acid fermentation. Four of such media were prepared with initial concentrations as follows; 50.942g/L, 82.04O0g/L, 1 19.872g/L and 158.272g/L. The media were inoculated with free spores of Aspergillus niger and incubated at 27 - 29°C. Four parameters of each fermentation media were analysed to determine how they influenced or were influenced by the fermentation process. These parameters were the pH, citric acid production, sucrose consumption and biomass production. The fungus was found to be successfully cultivated on all the four media, thus causing the media to be more acidic as a result of the production of citric acid, decreasing the pH from an average value of 4.03 to 2.20. All the four parameters were found to be significantly different at 5%. The differences that existed between these values might be due to a metabolic control mechanism such as substrate inhibition by the highly concentrated substrate above 1l9.872g/L. Thus the optimum sucrose was found to be 119.9g/L corresponding to the media supplemented with 400grams of sugar (M - 4S).
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, in partial fulfilment of the requirements for the award of the Degree of Master of Science in Environmental Science, 2000