Multi-Objective Statistical Optimization of Pectinolytic Enzymes Production by an Aspergillus sp. on Dehydrated Coffee Residues in Solid-State Fermentation

Abstract

Pectinolytic enzymes are a group of enzymes widely used in the food industry. They can be obtained through a wide range of by-products and agricultural and agro-industrial waste by the action of fungi, such as Aspergillus spp., by solid-state fermentation (SSF). A wild strain of an Aspergillus sp. isolated in the Universidad Técnica del Norte (UTN) was used to obtain pectinolytic enzymes from dehydrated coffee waste (pulp and husk) derived from coffee cherries cultivated in the Ecuadorian Andean regions. It was possible to find a condition in which the production of pectinases (expressed as Enzymatic Activity (EA)) and the concentration of spores (S) were simultaneously maximized, using the response surface methodology, in a 3-level factorial design, by SSF in simple tray-type bioreactors. After the analysis and optimization of quadratic models, three confirmatory experiments were performed in the unique optimal condition recommended (35 °C and 79% relative humidity), obtaining 29.9 IU/g and 2.64 × 106 #Sp./g for EA and S, respectively; these values coincided with those predicted by the quadratic models, demonstrating their validity. The values obtained in this study are similar to those previously obtained by other authors.