Ilona Kołodziejska, Celina Niecikowska and Zdzisław E. Sikorski
Gdańsk University of Technology, Gabriela Narutowicza 11/12, 80-952 Gdańsk, Poland

Key words: mackerel fillets, sprats, smoked fish, lipid oxidation, lysine availability, wood smoke phenols.

Abstract.
Fatty fish are a valuable dietary source of proteins and of polyenoic fatty acids from the n-3 family. Smoking may affect the state of lipids and proteins due to heating and the reactivity of smoke components, predominantly phenols. The aim of this work was to investigate the effect of smoking in mild conditions on lipid oxidation and lysine availability in Atlantic mackerel fillets and sprats. There was large variability in the results regarding the state of the lipids and proteins in individual defrosted raw mackerel fillets taken from the same batch. No correlation was found between the degree of lipid oxidation and the contents of lipids in the thawed fillets. The ranges of the peroxide value and anisidine value were considerably high. Hot and cold smoking did not affect the peroxide value of mackerel fillets, while in smoked sprats it was much lower than in the thawed fish. Smoking did not cause any decrease in lysine availability, although the anisidine value increased about twofold in smoked mackerel and fourfold in smoked sprats. The contents of phenols were similar in the skins of the analyzed samples of all assortments of smoked fish and ranged from 19 to 24 mg/100 g. The phenol content in the meat of the smoked sprats was only 20% lower than that in the skin.