Hydrophobic Deep Eutectic Solvents (HDES) as an Alternative for the Extraction of Omega-3 Fatty Acids from Octopus maya By-Products

This study evaluated the use of HDES for omega-3 recovery from by-products of Octopus maya, an endemic species of the Yucatán Peninsula, Mexico. A 2 × 3 × 2 factorial design was applied to assess the effect of: (1) the hydrogen bond acceptor (HBA, menthol or eucalyptol) of hydrophobic deep eutectic solvents (HDES) with oleic acid as the hydrogen bond donor; (2) the molar ratio (MR) (1:1, 1:2, or 2:1); and (3) ultrasound-assisted extraction time (ET) (30 or 60 min) in omega-3 equivalents (EO3, mg/mL), determined by UV–Vis spectrophotometry and viscosity characterization to the Octopus maya extracted samples (n = 2), reported as x¯ ± SD. The effects of the factors studied were analyzed by a DOE methodology with Minitab® (version 18). Samples with the highest omega-3 were selected and their composition was confirmed by FTIR, Raman spectroscopy and gas chromatography. Eucalyptol at a molar ratio of 1:2 and an extraction time of 30 min yielded the highest OE3 (0.70 mg/mL). The statistical analysis revealed that the extraction of omega-3 determined by UV–Vis spectrophotometry was significantly influenced by the triple interaction of HBA × MR × ET (p < 0.05), indicating that extraction performance depends on the combined effect of solvent composition and processing conditions. All extracts showed Newtonian behavior with viscosities between 0.011 and 0.036 Pa·s, with eucalyptol formulations presenting the lowest values (0.011–0.023 Pa·s). Fatty acid profile allowed to quantify C16:0; C18:0; C18:1 n-9; C18:2 n-6; and C18:3 n-3, palmitic, stearic, oleic, linoleic and linolenic fatty acids, respectively, showing greater affinity for polyunsaturated fatty acids, mainly omega-6 (23.45–27.91%), and lower affinity for saturated fatty acids such as palmitic and stearic acids, indicating HDES as a sustainable alternative for selective extractions.