Quality and Stability of Liquid Smoked Kapreeta Fish During Refrigerated Storage

Abstract

In Egypt, Kapreeta fish (like tuna) as marine fish, is not appreciated among Egyptian consumers because it is bloody dark flesh and presence of many blood vessels.Therefore, this kind of fish must be utilized as fish products through different preservation methods as canning and smoking.The aim of this study is to investigate the effects of liquid smoking and essential oils prior smoking on the quality of smoked kapreeta fish fillets just after smoking and during refrigerated storage up to 90 days.Proximate composition was determined in fresh and smoked fish fillets.Chemical, microbiological and sensory analyses of the samples as well as fatty acids composition of fresh and smoked kapreeta fish fillets were carried out during the storage to test their quality and lipid stability.Moisture content decreased while protein, lipid and ash increased after smoking.The pH values were slightly increased by storage time.Total volatile basic nitrogen, trimethyl amine nitrogen, peroxide values, thiobarbituric acid, free fatty acids and total viable count values were increased more in untreated fish samples than smoked fish samples treated with thyme or sage essential oils, while sensory scores decreased during storage.The total polyunsaturated fatty acids content was 35.14% of total fatty acids in untreated smoked fish and 35.80% in treated samples with 5% thyme oil and 36.14% in treated samples with 5% sage oil prior to smoking, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) being the prominent polyunsaturated fatty acids.The decrease of PUFAs may indicate the oxidation of these unsaturated fatty acids during storage.Such changes were not observed in sage or thyme extracts treated lots.According to the results of physicochemical, microbiological and sensory analyses, it was found that untreated smoked kapreeta fish samples were in high quality and lipid stability for 30 days under refrigerated storage and smoked kapreeta fish samples treated with 5% thyme oil or sage oil were in high quality till 60 and 75 days under refrigerated storage.It can be concluded that kapreeta fish fillets treated with sage and thyme essential oils prior to liquid smoking have positive effect on quality and shelf life of smoked fish as well as induced the stability of fatty acids profiles without altering their composition and minimize oxidation.