Mutant Strain of <i>Aspergillus aculeatinus</i> Boosts Total Phenolic Compounds and Sugar Recovery from Coffee Residues via Enzyme-Assisted Extraction

Coffee residues are a valuable source of phenolic compounds and saccharides, which can be extracted through various methods such as solvent extraction, subcritical water extraction, and microwave-assisted extraction. Recently, enzyme-assisted extraction using microbial enzymes has emerged as a green and sustainable alternative. This study focused on enhancing cellulase and pectinase production in <i>Aspergillus aculeatinus</i> SF-034 through induced mutagenesis and evaluating the mutant enzymes for extracting polyphenols and saccharides from coffee by-products. The mutant QN-247 strain exhibited notably increased enzyme activities, with pectinase and CMCase levels approximately 31% and 120% higher than those of the mutant SF-034 and the wild-type strain, respectively. Scale-up in a 10-L bioreactor further confirmed high enzyme activities, reaching 995.8 U/ml for pectinase and 888.7 U/ml for CMCase. Enzyme-assisted extraction using the QN-247 mutant enzymes significantly enhanced the release of polyphenols (9.0-31.7 mg GAE/g) and glucose (166.7-208.3 mg/g biomass), outperforming commercial enzyme preparations under the assay conditions. These findings highlight the QN-247 strain as an efficient producer of multi-enzyme cocktails that offer a sustainable approach for extracting valuable bioactive compounds from coffee residues and other agricultural by-products.