Sevim Köse

High docosahexaenoic acid levels in both neutral and polar lipids of a highly migratory fish: Thunnus tonggol (Bleeker).

The lipid and FA compositions of various organs (light muscle, dark muscle, liver, pyloric cecum, and the orbital region) and of the stomach contents of a highly migratory fish species Thunnus tonggol (Bleeker) were analyzed. TAG and phospholipids (PE and PC) were the major lipid classes in the total lipids of T. tonggol. DHA was characteristically the major FA of all the major classes of all its organs except for only one case of liver TAG. The mean DHA contents of the various organs accounted for more than 20% of the total FA (TFA), even though it is a neutral depot lipid. However, DHA in the stomach contents, originating from their prey, fluctuated and was generally low. DHA levels were generally higher in a year (2000) when water temperatures were colder than in one when it was warmer (1998). Furthermore, DHA levels in muscle TAG were consistently high in spite of the fluctuation of those in the visceral TAG, which might be directly influenced by the prey lipids. This phenomenon suggests the physiological selective accumulation of DHA in the muscle, after the migration of the digested FA in the vascular system and absorption of the prey lipids in the intestine. In contrast, the FA composition of other species is generally variable and their DHA contents of TAG are usually less than 20% of TFA.

Non-ionic micellar electrokinetic chromatography with laser-induced fluorescence: a new method tested with biogenic amines in brined and dry-salted fish.

A non‐ionic micellar electrokinetic chromatography method coupled to laser‐induced fluorescence detection was developed for the quantitative determination of biogenic amines. Complete resolution of six biogenic amines – FITC derivatives – was achieved in less than 10 min, employing 10 mM Brij 35 in 75 mM borate buffer and at pH 9.7 as the running electrolyte. Relative fluorescence intensities of biogenic amines enhanched considerably and separation time decreased considerably when Brij 35 was substituted for SDS in the same buffer. The detection limits of the method for biogenic amines were found between 0.416 and 1.26 nM. The precisions for the corrected peak areas were calculated as between 1.63 and 3.24 %RSD. The applicability of the method was demonstrated by analyzing biogenic amines in the processed, brined, and dry‐salted fish samples. The method is simple and rapid, and widely applicable for the determination of biogenic amines in food samples.

Changes in the levels of histamine during processing and storage of fish meal

Abstract Processing and storage trials were carried out under controlled laboratory conditions to investigate the effect of processing and storage conditions on histamine formation during fish meal production. It was found that most histamine concentrated in the press liquor (stickwater) meal after processing. Histamine levels were mainly decreased in mackerel samples but increased in cod samples after processing into fish meal. Histamine was detected in the fish meal samples of fish offal of both cod and mackerel. No bacterial growth was observed in the press-cake when fish was cooked and pressed during fish meal production. After drying of solids and the stickwater, bacterial growth was observed. This is an indication that fish meal is apparently microbiologically hygienic after cooking process, then recontamination occurs. That samples were packed in polyethylene bags seemed to show a slight increase in histamine levels up to fifth week but a significant decrease (P

The Variations in Proximate Chemical Composition and Fatty Acid Profile in Different Parts of the Thornback Ray (Raja clavata) Caught from Black Sea, Turkey

Proximate chemical composition and fatty acid (FA) profile of different parts and sexes of ray (Raja clavata) were compared. The proximate values of liver samples significantly differed from other body parts (p < 0.05). Pectoral fin had the highest moisture, protein, and ash contents (78.6, 20.5, and 1.2%, respectively). The highest fat content (39.7%) was observed for liver samples. A significant variation was also observed between sexes in terms of proximate and FA values (p < 0.05). The levels of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) varied between 27.1–32.1, 14.9–19.0, and 34.3–39.5%, respectively, in total fatty acid methyl esters (FAME). The highest total PUFA and docosahexaenoic acid (DHA) values were observed in the edible portion of liver for both sexes due to high contents of fat, despite the low values of % total FAME in comparison with other body parts. Significant variations among FA levels were observed for different body parts (p < 0.05). The highest DHA and eicosapentaenoic acid (EPA) values were found in the edible portion of the liver and calculated as 6.8 and 2.3 g/100 g, respectively, indicating the importance of utilizing the liver of this species.

Levels of heavy metals in blue whiting caught from the eastern Black Sea area of Turkey

This paper presents data on the concentrations of 5 metals, copper (Cu), cadmium (Cd), iron (Fe), zinc (Zn) and lead (Pb) in Blue Whiting sampled from the Eastern Black Sea coast of Turkey. The highest metal concentrations of Cu, Cd, Fe, Zn and Pb were recorded in Blue Whiting with the values of 2.71, 0.601, 14.137, 15.322 and 1.078 μg g‐1 dry weight, respectively. On average the metal concentrations in Blue Whiting followed the order of Zn > Fe > Cu > Pb > Cd. Temporal differences of concentrations of these metals were significant (p < 0.05). Spatial fluctuations of Cu, Cd, Fe, Zn and Pb concentrations in Blue Whiting were also significant (p < 0.01). It was found that the concentrations of Cu, Cd, Fe, Zn and Pb in the muscle in Blue Whiting were below the limit of Public Health Regulation in Turkey.

Seasonal Changes in Proximate Composition and Fatty Acid Profile of Pufferfish (Lagocephalus sceleratus Gmelin, 1789) from the Mediterranean Sea of Turkey

This study represents a first report on the proximate composition and fatty acid profile of Lagocephalus sceleratus from the Mediterranean Sea as well as seasonal changes and sexual differences. Significant variations in the proximate composition were observed during the months of the study (p < 0.05). The highest moisture, fat, protein, and ash contents were found to be 78.47, 0.33, 21.62, and 1.63%, respectively. Total saturated and monounsaturated fatty acid values were similar throughout the year despite individual variations of 24.22–29.46 and 7.87–13.94%, respectively. However, significant variations were observed in total polyunsaturated fatty acids as well as significant differences between sexes (p < 0.05) with some exceptions. The major fatty acid was found as docosahexaenoic acid (DHA), between 24.17 and 32.65%. Due to the low fat content of this species, the highest eicosapentaenoic acid (EPA) + DHA values were calculated as 80.93 mg/100 g of edible muscle. The results indicated that this species contains high nutritional properties in terms of protein content and fatty acid values.

Solar drying of rainbow trout

The aim of this study is to dry rainbow trout (Oncorhynchus mykiss) by employing a solar energized system. For this purpose, an experimental apparatus was built in the Energy Research Laboratory of Mechanical Engineering Department, Karadeniz Technical University, Trabzon, Turkey. The pre-treated fish samples were dried at 33–36°C with about 1·8 m/s air velocity in 3 days. Results showed that the samples dried very quickly in the first 15 h of drying then a slow process occurred. The drying process was completed in about 75 h. It was concluded that fish drying is possible in the North East Black Sea region or other areas with a similar climate by a solar energy system if an additional heater is used. This technique was found to be safe for changeable weathers as well as simple. This system has economical advantages compared to other methods applied alone, and can also be used for other drying applications. Copyright

Variations in Total Lipid and Fatty Acid Contents of Edible Muscle, Liver, and Roes of Spotless Shad, Alosa Immaculata, During Catching Season in Black Sea

ABSTRACT Monthly variations of lipid and fatty acid contents in muscle, liver, and roes of Alosa immaculata from the Black Sea were investigated. Lipid contents of muscle were higher than the levels obtained for liver and roes at 15.8–21.2%. Significant variations occurred in fatty acid levels (p < 0.05). Edible muscle and roe samples contained higher total polyunsaturated fatty acids (∑PUFA) in comparison with total saturated (∑SFA) and monounsaturated fatty acids (∑MUFA), while the majority of fatty acids were represented by ∑MUFA for liver samples. The highest ∑PUFA for edible muscles and roes were both obtained in March as 38.3 and 39.5%, respectively, while the highest ∑MUFA level was found for liver in February as 42.3%. The study showed that about 43–106 g of edible shad muscle will be enough to cover the weekly requirement of EPA + DHA, while less than 12 g of shad muscle should satisfy the daily n-3 PUFA intake. The results indicate that A. immaculata caught from the Turkish Black Sea is a good source of omega-3. This information can be used for commercialization of shad and also may aid further studies on physiology of shad species. Moreover, these results are useful to evaluate the utilization of by-products of this species for sustainable fisheries.

Quality Changes and Shelf Life of Cultured and Wild Hot-Smoked Mediterranean Horse Mackerel (Trachurus mediterraneus) at Refrigerated (4 ± 1°C) Conditions

ABSTRACT Mariculturing of horse mackerel is not known in the world. Additionally, limited studies exist on quality changes of smoked horse mackerel at refrigerated temperatures. Therefore, in this study, between 1+ and 2-year-old wild and cultured horse mackerels were hot smoked and stored at refrigerated conditions. Chemical, microbiological, and sensory analyses were performed weekly to investigate quality changes and to determine the shelf stability of the products. The results of thiobarbituric acid, trimethylamine, and total bacteria counts were obtained within the acceptable levels. Although the counts of histamine-forming bacteria increased significantly (p < 0.05) during storage, histamine values were well below the permitted limits set by Food and Drug Administration and European Union (EU). Sensory results showed that both storage groups had 3 weeks of shelf life. Total volatile basic nitrogen values supported sensory results. Therefore, the results indicate that culturing of horse mackerel did not alter the quality during storage at 4 ± 1°C.

Comparison of Proximate Composition and Fatty Acid Profile of On-Growing and Wild Mediterranean Horse Mackerel (Trachurus mediterraneus)

ABSTRACT On-growing of horse mackerel is not known in the world. Recently, we have initiated on-growing of the Mediterranean horse mackerel in the Black Sea. Therefore, we aim to compare proximate composition and fatty acid profile of on-growing and wild horse mackerels to evaluate the effect on their nutritional value. Captured horse mackerels less than 13 cm were kept on-growing in sea cages and fed sea bass feed for a year in the southern Turkish Black Sea. Results showed seasonal variations in the proximate contents and fatty acid profile of both on-growing and wild fish groups (p < 0.05). Protein contents of the wild horse mackerel group were significantly higher than the on-growing mackerel group, while the opposite situation was observed for lipid contents (p < 0.05). Despite higher eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels (as fatty acid methyl esters %) of wild horse mackerel in comparison with on-growing group, much higher EPA + DHA contents were accounted for in on-growing fish in the edible portion resulting from higher lipid contents of these samples. The results suggest that lower amounts of fish meat, 50–90 g, from on-growing mackerel would cover the daily suggested value of EPA + DHA; this level is calculated as 51–150 g for wild fish meat.