Diana A. Dobreva

Nutritional evaluation of aquaculture mussels (M. galloprovincialis) from the Black Sea, Bulgaria

Abstract In recent years black mussels are one of the most commercially important species from the Bulgarian Black Sea. The marine mollusks are valuable healthy food, low in calories and fats and high in proteins. They are a major dietary source of fat soluble pigments - astaxanthin, carotenoids and polyunsaturated fatty acids (PUFA). To our knowledge the information about the nutritional quality of mussels from the Bulgarian Black Sea waters, based on chemical composition, fat soluble pigments, cholesterol and PUFA content is very limited. The aim of the present study is to determine and compare protein, lipid, carbohydrate and energy values, fat soluble pigments, cholesterol and fatty acid composition in farmed mussels (Mytilus galloprovincialis) from the Bulgarian northern and southern parts of the Black Sea coast. The mussel samples were analyzed for lipids (Bligh & Dyer method), crude proteins (Kjeldahl method), carbohydrates and moistures according to the AOAC (1990) methods. Fatty acids were analyzed by the GC-MS system. Fat soluble pigments and cholesterol were analyzed simultaneously by the RP-HPLC system. Lipid and protein content were found to be higher in mussels from the northern region. In accordance with the Commission Regulation (EC) No. 116/2010 all analyzed mussel samples can be classified as high in protein and low in fats and carbohydrates. The amount of cholesterol, contained in all mussel populations is significantly low, while the omega-3 (n-3) is significantly higher than the omega-6 PUFA. A portion of 100 g edible tissue provides 0.500 g more of the required amount of eicosapentaenoic acid (20:5) and docosahexaenoic acid (22:6) n-3 PUFA according to EFSA (2012). It can be concluded that the studied mussel aquaculture in the Black Sea is beneficial food for the human health and it is advisable to be part of a proper or a preventive diet of Bulgarian consumers.

Bulgarian Marine and Freshwater Fishes as a Source of Fat-Soluble Vitamins for a Healthy Human Diet

The aim of the present study evaluates the fat-soluble vitamins all-trans retinol (vitamin A), cholecalciferol (vitamin D₃) and α-tocopherol (vitamin E) content in the fresh edible tissue of Bulgarian fish species: marine-grey mullet (Mugil cephalus) and bonito (Sarda sarda), and freshwater-rainbow trout (Oncorhynchus mykiss) and common carp (Cyprinus carpio). The sample preparation procedure includes alkaline saponification, followed by liquid-liquid extraction with n-hexane. All-trans retinol, cholecalciferol and α-tocopherol were analyzed simultaneously using RP-HPLC\UV\FL system with analytical column C18 ODS2 Hypersil™. The fat soluble vitamins content (μg per 100 g wet weight) in the fresh edible fish tissue of analyzed fishes are in the ranges: vitamin A from 2.7 ± 0.4 to 37.5 ± 3.4 μg/100 g ww; vitamin D₃ from 1.1 ± 0.1 to 11.4 ± 0.6 μg/100 g ww; vitamin E from 121.4 ± 9.6 to 1274.2 ± 44.1 μg/100 g ww. Three fat-soluble vitamins occur in higher amounts in rainbow trout and grey mullet species. According to recommended daily intake (RDI), they are a good source of cholecalciferol.

Fat Soluble Vitamins, Cholesterol, and Fatty Acid Composition of Wild and Farmed Black Mussel (Mytilus galloprovincialis) Consumed in Bulgaria

ABSTRACT The most commercially important mollusk species from the Bulgarian Black Sea is the black mussel (Mytilus galloprovincialis). There is limited information about fat soluble vitamins, cholesterol, and fatty acid content of the Bulgarian Black Sea mussel. The aims of the present study are to determine and compare the fat soluble vitamin contents as well as relative daily intake of vitamins, cholesterol, fatty acid content, and lipid quality indices (atherogenic, thrombogenic) in the wild and farmed black mussels. Fat soluble vitamins and cholesterol were analyzed simultaneously using reverse phase high performance liquid chromatography. The fatty acid composition was analyzed by gas chromatography-mass spectrometry. In both mussels, fat soluble vitamins A and E were in high amounts, but they were a better source of vitamin D3. Cholesterol contents were 67.54 ± 0.50 mg/100 g ww (wild) and 49.88 ± 0.30 mg/100 g ww (farmed). The fatty acid distributions of wild and farmed mussels are: saturated > polyunsaturated > monounsaturated fatty acid. The n3/n6 and polyunsaturated/saturated fatty acid ratios were greater than that recommended by the Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO). A 100-g edible portion of both mussels contained from 0.252 g (wild) to 0.425 g (farmed) of eicosapentaenoic acid (EPA, C20:5n-3) + docosahexaenoic acid (DHA, 22:6n-3).

Fat soluble vitamins and fatty acid composition of wild Black sea mussel, rapana and shrimp

Abstract Many studies suggest that marine molluscs are one of the most important dietary sources of fat soluble vitamins (E, D3 and A) and essential fatty acids (FA). The most commercially important species from the Bulgarian Black Sea are the Black mussel, rapana and shrimp. There is scarce information in the scientific literature about fat soluble vitamins and FA composition of these Black Sea molluscs. The aims of the present study are to determine and compare fat soluble vitamins content as well as relative daily intake, FA composition and atherogenic index (IA), thrombogenicity index (IT) and flesh-lipid quality index (FLQ) in wild Black Sea mussel (Mytilus galloprovincialis), rapana (Rapana venosa) and shrimp (Crangon crangon). Fat soluble vitamins were analysed simultaneously using RP-HPLC system. The FA profile was analysed by GC-MS. All of the analysed samples presented significant amounts of vitamin E, followed by vitamin A and D3. Black Sea molluscs are excellent sources of fat soluble vitamins, especially for vitamin D3 - one survey provides more than 100% of the RDI established in Bulgaria. The FA composition of total lipids showed significant differences and the present study revealed that SFA content was significantly higher than MUFA (p<0.001) and PUFA (p<0.001) (SFA>PUFA>MUFA) in shrimp and mussel whereas rapana showed opposite trends (PUFA>SFA>MUFA). The omega6/omega3 and PUFA/SFA ratios of the analysed species were greater than the FAO/WHO recommendations.

Fatty acid and fat soluble vitamins composition of raw and cooked Black Sea horse mackerel

Abstract The fat soluble vitamins, as well as n3 and n6 fatty acids (FA) are essential compounds of fish lipids and exclusively provided by the diet. Fish is sometimes eaten raw, but it is usually thermal processed before consumption. Temperature processing of fish tissue enhances its taste, inactivates pathogenic microorganisms and increases its shelf life. The fat soluble vitamins (vitamins A, D3 and E) and fatty acids are considered to be susceptible to oxidation during heating (cooking) process. The aim of the present study was to evaluate the effect of steaming (10 min at 90°C) and frying (5 min on the each side with sunflower oil) on fat soluble vitamins and fatty acids composition in Horse mackerel (Trahurus mediterraneus) fish fillets. Vitamins A, D3 and E were analyzed simultaneously using RP-HPLC. The fatty acid composition was analyzed by GC-MS. The amounts of vitamin A (retinol) in cooked fish fillets (for both heat treatments) decreased significantly, compared to their content in the raw samples. In contrast vitamin D3 (cholecalciferol) content affects only by steaming, while changes on vitamin E (alpha-tocopherol) was observed solely after frying process. The highest content of monounsaturated fatty acids (MUFA) were observed after steaming, whereas fried samples presented higher values of polyunsaturated fatty acids (PUFA) due to significant increase in linoleic acid (C18:2n6). During steaming did not reduce significant n3 and n6 PUFA levels, while frying caused a large reduction of n3 PUFAs. The ratio of n3/n6 was markedly lower in fried samples than in raw and steamed mackerel. In conclusion the Black Sea Horse Mackerel is a good source of vitamin D3, vitamin E and n3 PUFAs. After steaming and frying process there were minimum losses in the contents of cholecalciferol and alpha-tocopherol, while retinol was reduced nearly a half. The process of frying affects most significantly three fatty acids groups, whereas after steaming was observed little influence on fatty acids profile.

Alpha-tocopherol and ergocalciferol contents of some macroalgae from Bulgarian Black Sea coast

Abstract The aim of the present study was to determine and compare _-tocopherol and ergocalciferol content in four macroalgae from Bulgarian Black sea coast. Ulva rigida, Cladophora vagabunda, Cystoseira barbata and Cystoseira crinita were used for evaluation of corresponding fat soluble vitamins content. The sample preparation procedure includes alkaline saponification, followed by liquid-liquid extraction. Ergocalciferol (vitamin D2) and α-tocopherol (vitamin E) were analyzed simultaneously using HPLC/UV/FL system (Thermo Scientific Spectra SYSTEM) equipped with RP analytical column. The mobile phase was composed of 97:3 = MeOH:H2O. Ergocalciferol was monitored by UV detection at λmax = 265nm, while α-tocopherol was detected by fluorescence at λex=288nm and λem=332nm. Alpha-tocopherol content in algal tissues ranged from 1.68±0.38mg/100g d.w. in Cladophora vagabunda to 29.13±1.08mg/100g d.w. in Cystoseira barbata. Ergocalciferol was detected only in Ulva rigida samples.

Retinol, cholecalciferol and alpha-tocopherol contents of Bulgarian Black Sea fish species

Abstract The aim of the present study is to determine and to compare the content of retinol, cholecalciferol and alpha-tocopherol in edible tissue of two Black sea fishes - Garfish (Belone belone) and Turbot (Psetta maxima). All-trans-retinol (vitamin A), cholecalciferol (vitamin D3) and alpha-tocopherol (vitamin E) were analyzed simultaneously using HPLC/UV/FL system (Thermo Scientific Spectra SYSTEM) equipped with RP analytical column. The mobile phase was composed of 97:3 = MeOH:H2O. Retinol and cholecalciferol were monitored by UV detection at lmax = 325 nm and lmax = 265 nm, respectively. Alpha-tocopherol was detected by fluorescence at lex=288 nm and lem=332 nm. The sample preparation procedure includes alkaline saponification, followed by liquid-liquid extraction. Quantities of all-trans-retinol and cholecalciferol were higher in garfish tissues while alpha-tocopherol content in turbot showed seven times higher values.

Lipid composition of raw and cooked Rapana venosa from the Black Sea

Abstract Rapana venosa is an edible mollusc with nutritional and economic importance. There is limited information about its lipid composition. The aim of the present study is to provide information about lipid composition, fatty acid profiles, fat soluble vitamins and cholesterol content of raw and cooked Rapana venosa. Cooking did not affect the ratio of lipid classes, but fatty acids composition varied significantly. Considerable variations were observed in fatty acid distribution of total lipids and neutral lipids. Fatty acid groups of phospholipids remained unaffected by temperature treatment. The most abundant fatty acids in all lipid classes of raw and cooked specimens were palmitic acid (C16:0) and eicosapentaenoic acid (C20:5n-3). The sum of omega-3 polyunsaturated fatty acids (PUFA) was higher than omega-6 PUFA in all lipid fractions. The results of the present study showed that cooking process affected cholesterol, fat soluble vitamins and carotenoids content differently. Larger variations were observed for vitamin A, β-carotene and astaxanthin and to lesser for vitamin E. Cholesterol and vitamin D3 were also affected by the thermal stress. The present study revealed that Rapana venosa meat could be a good source of high quality nutritional lipids, which are well preserved even after culinary treatment

Comparison of fatty acids, cholesterol, fat soluble vitamins and carotenoids content of skin and edible tissue of farmed African catfish (Clarias gariepinus, Burchell 1822)

Abstract African catfish (Clarias gariepinus) is new species for the Bulgarian market. It is a valuable source of biologically active components that play an important role in human diet, but there is lack of information for the quality of its dietary lipids. This study focuses on the assessment of skin and edible tissue lipid quality of farmed African catfish based on lipid content and detailed fatty acids, fat-soluble vitamins, cholesterol and carotenoids composition. Fatty acid composition was determined by gas chromatography with mass spectrometer (GC/MS) after lipid extraction. Vitamins A, D3 and E, beta-carotene, astaxanthin and cholesterol were analyzed simultaneously using high performance liquid chromatography (HPLC) with ultraviolet and fluorescence detectors. Lipids, cholesterol, astaxanthin and monounsaturated fatty acids (MUFA) were significantly higher in skin, whereas vitamin A and E, polyunsaturated fatty acids (PUFA) were higher in muscle tissue. Vitamin D3 showed comparable amounts in both tissues. Eicosapentaenoic acid (C20:5n3) and docosahexaenoic acid (C22:6n3) which are important indicators for fish lipids quality presented significantly high amounts. A portion of 100 g filet without skin contains approximately 600 mg. Results confirmed that African catfish meat - with or without the skin, can be valuable and preferable source of biologically active lipids.

Fish Lipids as a Valuable Source of Polyunsaturated Fatty Acids

Abstract This article presents information about omega-3 (h-3) and omega-6 (n-6) polyunsaturated fatty acid (PUFA) contents in a broad range of commercially important fish species available on Bulgarian fish markets. The aim is to raise consumers’ awareness and encourage them to eat fish. Fish species from the Black Sea coast have relatively high proportion of n-3 PUFAs, of which more than 80% is by EPf (eicosapentaenoic acid, C 20:5 n-3) and DHA (docosahexaenoic acid, C 22:6 n-3). Extensive epidemiological studies show that fish consumption is inversely associated with the incidence of cardiovascular diseases (CVD), stroke and the functioning of the brain. About 0.5 g of omega-3 (EPA+DHA) a day or two savings of oily fish a week are required to reduce the risk of death from CVD. PUFAs needs should be satisfied not only with food additives but with fish lipids containing food.