An enzymatic approach for producing chitin from snow crab and American lobster seashells

Shellfish processing plants generate large volumes of by-products rich in high-value biomolecules such as proteins, minerals, and chitin. Currently, chitin extraction is mainly carried out by chemical hydrolysis using strong acids and bases, a method with a large environmental impact. To address these concerns, a sustainable enzymatic approach was developed for extracting chitin from snow crab and American lobster shells. Different acid-active proteases were tested to identify the most effective enzyme for simultaneous deproteinization and demineralization of the shells. Pepsin demonstrated the highest efficiency, achieving over 95% demineralization and 78% deproteinization. The process was further optimized to minimize enzyme concentration and hydrolysis time. The respective optimum parameters for crab and lobster were 3130 and 2070 U of pepsin per gram of protein for 2.5 hours. In these conditions, deproteinization rates of 74.0% and 81.1% and demineralization rates of 94.5% and 90.8% were achieved for crab and lobster shells, respectively. Additionally, soluble proteins from the enzymatic hydrolysis were recovered and characterized, demonstrating their potential for use in animal feed and for bioactive peptides production. • Sustainable chitin extraction was achieved with efficient one-step pepsin hydrolysis • A second pepsin hydrolysis improved the purity of chitin • Shell soluble proteins were recovered and identified through proteomic analysis • Soluble shell proteins could be used as animal feed or bioactive peptides