Valorization of fish oil byproduct methyl esters for omega‑3 polyunsaturated fatty acids production via immobilized CALB lipase‑catalyzed hydrolysis

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) offer therapeutic benefits, including triglyceride reduction and management of cardiovascular and neurological disorders. This study investigates the use of fish oil processing by‑products, which consist mainly of fatty acid methyl and ethyl esters, as novel substrates for n‑3 PUFAs production. To overcome the low efficiency of conventional chemical methods and the vulnerability of free lipase to alcohol toxicity and poor reusability, we developed a stable immobilized lipase system. The target enzyme (CALB) was immobilized onto macroporous resin LXTE‑1000 via adsorption‑crosslinking, and optimal hydrolysis conditions were determined. The resulting immobilized enzyme (LXTE‑1000@CALB) showed markedly enhanced thermal and operational stability, retaining approximately 64.21% of its initial hydrolysis degree over ten consecutive batches. This work provides an efficient, green, and sustainable approach for valorizing fish oil by‑products and producing n‑3 PUFAs. Graphical abstract