PRODUCTION OF CITRIC ACID FROM SUGARCANE MOLASSES BY ASPERGILLUS NIGER USING SUBMERGED FERMENTATION

CITRIC ACID FROM MOLASSES USING SUBMERGED FERMENTATION

Abstract

Citric acid (CA) has a high demand due to its various uses in the food and pharmaceutical industries. However, the natural supply of citric acid is very limited as compared to its growing industrial demand. The increasing demand for CA can be fulfilled by using biotechnological processes. This study was conducted on liquid state bioconversion by Aspergillus niger for the production of citric acid using sugarcane molasses as the main substrate. As sugarcane, molasses considered as a waste, which consists of a big proportion of the organic matter such as lipids and carbohydrates. It makes sugarcane molasses a potential and alternative source of producing citric acid for a lower cost. Aspergillus niger was cultured in potato dextrose agar. Then, spores inoculum introduced into the fermentation media for a specific duration according to the Design Expert 6.0 software. In this study, sequential optimization strategy, based on statistical designs, applied to improve CA production using submerged fermentation. Three parameters examined to determine the best process optimization conducted in shaking flasks. Response surface methodology (RSM) was adopted to obtain the best conditions for the process, where two-level factorial designs with three parameters were employed for the fermentation. It was carried out at room temperature (32â°C), agitation was set at three different values which are 160, 180 and 200 rpm. Another parameter was substrate concentration where 47%, 60%, 73% introduced. The fermentation carried out for the duration of one to five days. Initial pH was set at (5) five. Three quantitative and qualitative tests were conducted in order to assure its identity and measure CA yield, which was Titration, HPLC and FTIR spectroscopy. Qualitative estimation of CA in the cultivation media obtained using FTIR analyses. The optimization study showed that the media incubated for 72 hours with a substrate concentration of 60% and an agitation speed of 180 rpm produced the highest CA yield using High Performance Liquid Chromatography (HPLC) method. The analysis of variance (ANOVA) also showed that the HPLC optimization model was significant with p < 0.0104 and R² = 0.8964.