Low-cost extraction of multifaceted biological compounds from citrus waste using enzymes from Aspergillus Niger LBM 134

Abstract Agricultural industries search for biotechnological alternatives for waste management as they mean a significant concern and environmental challenge. More importantly, within a circular economy concept, such secondary substrates can be used to produce value-added compounds. This work is aimed at obtaining bioactive compounds from citrus waste by using a homemade enzymatic cocktail from Aspergillus niger LBM 134. The fungal enzymes were produced using raw sugarcane bagasse as substrate, which increased the ecological sustainability and the cost-effectiveness of the bioprocess. As the most relevant enzyme of this cocktail, a β-glucosidase showed to optimally act at 50 °C, retaining up to 70% of residual activity after 72 h. By means of an optimized enzyme-assisted extraction, the crude enzymatic cocktail produced was efficiently employed to extract the phenolics hesperetin, quinic, p -coumaric, and gallic acid, and the bioactive amino acid tryptophan from citrus waste. These assays yielded approximately 112% and 30% of phenolic compounds over alkaline conventional and commercial enzyme extraction methods, respectively. Graphical Abstract