Effect of hot smoking on proximate, fatty acid and amino acid composition of the European eel (Anguilla anguilla)

The effects of hot smoking on the proximate composition, amino acid profile, and fatty acid composition of European eel (Anguilla anguilla) were investigated. Hot smoking significantly reduced moisture content (from 65.67 to 56.78 g/100 g) while increasing protein (17.76 to 21.45 g/100 g), lipid (14.17 to 18.16 g/100 g), and ash (1.26 to 2.74 g/100 g) concentrations (p<0.05), consistent with a moisture-driven concentration effect amplified by mineral absorption during brining. Glutamic acid, leucine, and aspartic acid were the dominant amino acids in both groups. Total amino acid content increased significantly from 15.50 to 20.51 g/100 g following smoking (p<0.05), with essential amino acid scores exceeding FAO/WHO/UNU (2007) reference values for all quantified EAA in both raw and smoked samples. The TEAA/TAA ratio remained stable at approximately 52.5% across treatments, and the predicted protein efficiency ratio did not differ significantly between groups (p>0.05), confirming the preservation of relative protein quality following processing. Regarding fatty acid composition, oleic acid (C18:1n–9) and palmitic acid (C16:0) were the dominant fatty acids in both groups. Smoking caused a significant increase in total saturated fatty acids (SFA: 31.23 to 41.18%) and significant decreases in total monounsaturated (MUFA: 47.14 to 40.75%) and polyunsaturated fatty acid (PUFA: 21.62 to 18.04%) fractions (p<0.05). However, when expressed on a wet-weight basis (g/100 g), absolute EPA+DHA content was nutritionally equivalent between groups (raw: 1.24 vs. smoked: 1.29 g/100 g), reflecting the concentration effect of lipids following moisture loss. The omega 3/omega 6 (n‒3/n‒6) ratio was 3.19 in raw and 3.33 in smoked eel, with no significant difference between groups. These findings indicate that while hot smoking alters the relative fatty acid distribution, European eel retains its nutritional value as a high-quality protein and n–3 fatty acid source following processing.