Citric acid production by Aspergillus niger AN 400 from agroindustry waste

ABSTRACT The agro-industry generates large volumes of waste with high organic load, which requires the development of technologies to minimize the impacts caused by the improper disposal of this waste on the environment. The citric acid produced by agro food wastes as substrate for fermentation is a solution to reduce the organic load of these pollutants and add economic value by generating a profitable product. Aspergillus niger AN 400 was used to produce citric acid from cheese whey. The study was divided in three phases according to the addition of extra sugar (50, 100, 150 g.L-1): Phase I, with glucose; Phase II, with sucrose, and Phase III, with cheese whey only, without adding extra sugar. The reactors remained under agitation 150 rpm and at 30ºC for 10 days. The highest concentration of citric acid (2,379 mg.L-1) was observed upon the addition of 100 g.L-1 of glucose. However, the greatest yields were recorded in the reactors with 50 (458 mg.L-1.day-1) and 100 g.L-1 (745 mg.L-1. day-1) of sucrose, followed by the reactor that contained only cheese whey, without adding extra sugar (313 mg.L-1.day-1), demonstrating the potential of this waste to obtain citric acid with a great commercial interest.