Fungal production of citric acid

Overview of citric acid production from Aspergillus niger

“…A decrease in the accumulation of citric acid with iron has been observed, as well as changes in mycelial growth (Mischak et al 1985). Grewal and Kalra (1995) deduced that at a high zinc concentration, the fungi maintained growth without accumulation of citric acid (Drysdale & McKay 1995). Nickel, molybdenum and cobalt are some other trace metals reported to affect the citric acid accumulation of A. niger (Habison et al 1983).…”

“…Therefore, varying aeration rates can have adverse effects on the fermentation performance and yield (Grewal & Kalra 1995). At high aeration rates, there is reduced partial pressure of the dissolved carbon dioxide in the medium.…”

“…Solvent extraction is an alternative to the purification and crystallization of citric acid, as it has reduced environmental impacts compared with the precipitation method, by making use of n-octyl alcohol and tridodecylamine for citric acid extraction, thereby eliminating the production of gypsum. This method was also recommended by the US Food and Drug Administration for use in food and drug applications (Grewal & Kalra 1995). Electrodialysis makes use of electrically charged membranes, utilizing the electrical potential difference between the ionic and aqueous solution to separate them.…”

“…It is further concentrated by evaporation in a vacuum at 40°C. Lastly, crystals of citric acid monohydrate are formed in a vacuum crystallizer at a temperature of 20-25°C and anhydrous citric acid is formed at crystallization temperatures above 36.5°C (Kubicek 1986;Grewal & Kalra 1995). The wastes from this process include calcium sulphate, and microorganism residues containing amino acids, sugar, colloid, pigment and inorganic matter, which could be supplied to cement factories and dried for use in feed factories, respectively (Dhillon et al 2011b).…”

Citric acid production by Aspergillus niger van. Tieghem MTCC 281 using waste apple pomace as a substrate

“…There are many reports on effi cient utilization of agroindustrial residues and by-products for citric acid production using less expensive substrates, such as apple and grape pomace, carrot waste, orange and pineapple waste, cassava bagasse, coffee husk, kiwifruit peel, rice and wheat bran (Hang and Woodams 1986a, Grewal and Kalara 1995, Lu et al 1998, Soccol and Vandenberghe 2003. These residues are very well adapted to SSF due to their cellulosic and starchy nature.…”