Fungos filamentosos utilizados para produção de ácido cítrico e degradação de matéria orgânica de água residuária do café (Coffea arabica L.)

Abstract

Coffee is one of the most economically important agricultural products in Brazilian agribusiness. During grain processing, waste is generated, which is disposed of in inappropriate ways in the environment. Wet coffee processing generates large volumes of wastewater rich in organic and inorganic materials with high pollutant power, as well as a large amount of sedimentable solids, sugars, phenolic compounds, high chemical oxygen demand (COD) and biochemical demand oxygen (BOD). The objective of this work was to evaluate the production of citric acid by Aspergillus and Penicilium fungi in submerged fermentation using the wet processing wastewater as a fermentative medium in order to add value to this residue and to propose an alternative for this residue. reduction of the levels of organic matter present. Twenty acidity producing isolates were evaluated in medium containing coffee wastewater and in control medium. During fermentation, the sugar content, pH, mycelial weight and citric acid production were analyzed. As a result, it was found that the maximum yield of citric acid in coffee wastewater containing medium was 5,250 mgL-1 and in the control medium it was 20,102 mgL-1 after 196 h of fermentation for specie Aspergillus niger (A. niger 00194). Therefore, it is possible to use these agroindustrial residues for the production of citric acid. Of the genus Penicillium, the most citric acid producing species was Penicillium citrinum, which presented levels of 3,086 mgL-1 in the wastewater medium and 12,584 mgL-1 in the control medium, for the same fermentation time. Regarding the degradation of the organic matter present in the wastewater, Aspergillus niger (A. niger 00194) showed the highest degradation. BOD and COD values after fermentation were 8655,00 mgL-1 and 9156,30 mgL-1, respectively. Thus, a preliminary step in the treatment of coffee wastewater would be the use of these isolates to assist in the degradation of the organic matter present.