Cariny POLESCA1,2, Jason HALLETT1, Pedro NAKASU1
1Imperial College London, London, United Kingdom
2CICECO - Aveiro Institute of Materials, Aveiro, Portugal
The shellfish processing industry produces a substantial amount of waste – approximately 75% of the total weight of crustaceans – and there are no proper waste management solutions. The primary utilisation of shellfish waste is the production of chitin, one of the most commonly occurring polysaccharides worldwide, second only to cellulose, with total annual production by marine species estimated at millions of metric tonnes. It has potential as a biomaterial because it is biocompatible, bio-reactive and biodegradable but has low solubility, making it difficult to process. Squid pens are a by-product of squid processing and present β-chitin in their structure. β-chitin can be processed into β-chitosan, a valuable polysaccharide and more reactive than α-chitosan from shrimp and crabs. Squid pens contain a considerable amount of protein, 50-75 wt%, chitin and low amounts of lipids, lipoproteins, and minerals. During chitin production, a protein pre-extraction step is performed with dilute NaOH, generating a protein-rich lignin stream. However, this stream is currently considered waste and little attention has been paid to its recovery and use. In this work, we aimed to explore the use of ionic liquids (ILs) in the protein extraction of squid pens. After an IL screening between protic and aprotic ILs, [Ch][OAc] was chosen as the most suitable for protein extraction. The recovered proteins were then used to make biocompatible films that could potentially be used for packaging and/or biomedical applications. Additionally, ionic liquid recovered protein was compared with the ones obtained by the conventional alkaline process.