Optimized Production of Fungal Polygalacturonase Using Cupuaçu (Theobroma grandiflorum) Peel as Substrate and Its Effect on Clarification of Cupuaçu Juice

Pectinolytic enzymes play a key role in many beverages manufacturing processes, improving their clarification and filtration steps. Fungal pectinases are considered promising green catalysts for industrial applications, and they can be produced using fruit-processing residues as substrate. In this study, we investigated the optimal conditions to produce polygalacturonase from Aspergillus brasiliensis in a solid-phase bioprocess, using cupuaçu (Theobroma grandiflorum) peel as substrate. Then, the pectinolytic extract was applied in the clarification of cupuaçu juice. A central composite design was used to determine the optimal fungal cultivation conditions. Thus, the optimal fungal cultivation (maximum production of 11.81 U/g of polygalacturonase) was obtained using cupuaçu peel with 80% moisture, at 34 °C, for 7 days in a medium containing 4.2% phosphorus and 2.6% nitrogen. The enzymatic extract showed greater activity at 60 °C and stability at a pH range between 5.0 and 7.0. The pectinolytic extract was able to clarify the cupuaçu juice, causing a 53.95% reduction in its turbidity and maintaining its antioxidant activity. Our results demonstrate that the cupuaçu peel can be used as a substrate to produce polygalacturonase, and the enzymatic extract produced can be applied in the cupuaçu juice processing, contributing to the circular economy.