Enzymatic conversion and recovery of protein, chitin, and astaxanthin from shrimp shell waste

Accumulated shrimp shell waste is a source of environmental pollution and represents a waste of resources. Recycling shell waste into valuable fractions using cost-effective and environmentally benign approaches remains challenging. To address this issue, in this study a clean and efficient enzymatic process was developed to recover most components of shrimp shell waste including protein, chitin, astaxanthin, and minerals. The process used two recombinant aspartic proteases for protein hydrolysis, recombinant chitinase for chitin hydrolysis, and ethyl acetate for astaxanthin extraction. Deproteinization rendered shell chitin accessible to chitinase, and astaxanthin was easily extracted from shell residue after protein and chitin removal. The process was completed within hours and resulted in high recovery rates of protein (91.4%) and chitin (88.9%). Importantly, amino acids in peptides, the N-acetyl group of chitin oligomers, and astaxanthin in the final products were preserved in their natural states, unlike with traditional chemical or physical treatments. The products have potential applications in nutrition and as anti-inflammatory and antioxidant agents. This enzymatic process promotes sustainable development by establishing a circular economy in shrimp processing, thus offering both economic and environmental benefits.