Extraction of edible oils and amino acids from eel by-products using clean compressed solvents: An approach of complete valorization

Abstract

Green extraction methodologies using supercritical carbon dioxide (SC-CO₂) and subcritical water were used to valorize Conger myriaster skin (CMS). The omega-3 fatty acid content in CMS oil extracted using SC-CO₂ was 18.62 ± 0.08%, and vitamin A, D, E, and K₂ contents were 467.38 ± 0.46 μg/100 g, 8.31 ± 0.02 mg/100 g, 143.42 ± 4.61 mg/100 g, and 1.27 ± 0.05 mg/100 g, respectively. De-oiled CMS was hydrolyzed using subcritical water at temperatures ranging from 160 to 280 °C. Total protein, total sugar, and Maillard reaction product contents reached maximum values of 409.31 ± 2.86 mg bovine serum albumin (BSA)/g at 190 °C, 8.31 ± 0.31 mg glucose/g at 280 °C, and 0.240 ± 0.003 (Abs_420nm) at 220 °C, respectively. The highest antioxidant activity was observed at 280 °C. Free amino acids were abundant in the hydrolysates. Oil extraction from CMS using supercritical and subcritical fluids represents an effective and economical source of functional materials.

Keywords: Amino acids; Functional materials; Green compressed solvents; Heavy metals; Marine oils.