Research on fermentation process of citric acid in solid state using sugarcane bagasse and Aspergillus Niger

Abstract

Citric acid is an organic acid that has a wide range of applications in food industry and other industries. In the pharmaceutical industry, citric acid is used to produce different metal citrate salts so that these minerals can be biologically used in many medicines. For example, iron citrate made from citric acid provides iron to protect human blood, or is used to produce medicines in tablet or cream forms and cosmetics.

In this research, we investigated effects of technological factors on the fermentation process of citric acid in the solid state using sugarcane bagasse and Aspergillus Niger. We conducted an experiment to determine the content of citric acid obtained in fermented liquid using HPLC. The result showed that substrate humidity, culture ratio and duration significantly influence on the fermentation process. Through the investigation of water content change in solid state from sugarcane bagasse, we indicated that during the fermentation time, a fixed amount of water to be supplemented every day to maintain the initial humidity. Based on the results, we recommend a fermentation process of citric acid using sugarcane bagasse under the following condition: substrate humidity 80%, temperature 30^OC, 9-day duration, A.niger ratio 10% (v/w). The content of citric acid that can be obtained under the above condition is 12.02g/100g of sugarcane bagasse.