Mona Stancheva

Investigation about the presence of organochlorine pollutants in mussels from the Black Sea, Bulgaria

Abstract The aim of this study was to investigate the presence of polychlorinated biphenyls (PCBs), organochlorine pesticides (HCB, DDT and its metabolites) and HCBD in mussels from Bulgarian Black Sea coast. Mussels (Mytilus galloprovincialis) are aquatic organisms which are immobile so that the concentration of pollutants should primarily be considered as an indication of local levels of organochlorine compounds. Samples were collected from three areas of Black Sea coast of Bulgaria in summer 2015. The fifteen congeners of PCBs, HCB, HCBD, DDT and its metabolites DDE and DDD were performed by gas chromatography system with mass spectrometry detection. The metabolites DDE and DDD were found in all analyzed mussel samples, but PCBs were not detected in any sample. DDE concentrations were found in mussels from 1.09 to 1.63 ng/g wet weight. In mussel total DDT concentrations (2.14 ng/g ww) were found comparable to those in mussels, sampled in 2013 and 2014 (1.87 ng/g ww). The levels of DDTs and polychlorinated biphenyls in mussels from the Black Sea were found comparable to levels measured in the same molluscs from neighbor seas - Mediterranean Sea and Adriatic Sea.

Organochlorine contaminants (PCBs, DDTs, HCB & HBDE) in fish from the Lake Varna and Lake Beloslav, Bulgaria

Abstract Concentrations of organochlorine compounds such as polychlorinated biphenyls (PCBs), DDT and its metabolites, hexachlorobenzene (HCB) and hexachlorobutadiene (HBDE) were determined in three fish species: goby (Neogobius melanostomus), golden grey mullet (Mugil auratus) and silverside (Atherina boyeri). Samples were collected from the Lake Varna and the Lake Beloslav in 2014. The edible fish tissues were analyzed in order to investigate the presence of pollutants in species from the lakes near Varna City, Bulgaria and compared the results to the levels in other aquatic ecosystems. The fifteen congeners of PCBs, HCB, HCBD, DDT and its two main metabolites DDE and DDD were determined by capillary gas chromatography system with mass spectrometry detection. The OCPs levels in the wild fish were found in the order DDTs > PCBs. The other contaminants HCB and HCBD were not detected or were below the analytical detection limit. Among the pesticides, essentially only the metabolites p, p’- DDE and p, p’- DDD were found. The concentrations of DDTs were determined from 2.66 to 17.97 ng/g wet weight and PCBs concentrations were found from 0.43 to 8.05 ng/g ww (in goby and golden grey mullet, respectively). The sum of the six Indicator PCBs did not exceed the European maximum limit 75 ng/g wet weight. The concentrations of DDTs and PCBs were found lower compared to those in similar fish species from other aquatic ecosystems.

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.

Fatty acid composition of Bulgarian Black Sea fish species

Abstract The fatty acid compositions of three Black Sea fish species turbot (Pseta maxima), red mullet (Mullusbarbatus ponticus) and garfish (Belone belone) were investigated. This species are considered as preferred for consumption in Bulgaria. Lipid extraction was done according to the Bligh and Dyer method. The fatty acid composition was determined by GC/MS. The saturated fatty acids amounts were 38.32 % for turbot, 35.44 % red mullet and 42.90% for garfish. Monounsaturated fatty acids were found in lowest level in comparison with other groups for garfish (23.65%) and turbot (24.85%) while for red mullet they have a highest value - 37.56%. Omega 3 polyunsaturated fatty acids as eicosapentaenoic (C 20:5 omega 3, EPA) and docosahexaenoic (C 22:6 omega 3, DHA) acids were found in highest levels in turbot (22.26%) and garfish (21.80%) and in lowest values of red mullet (9.35%). The results showed that the fish examined are good source of omega 3 polyunsaturated fatty acids, resulting in a very favourable omega 3 / omega 6 ratios, especially in turbot and garfish

Fatty acids composition of macroalgae from Bulgarian Black Sea coast

Abstract Lipids and fatty acids (FA) composition of three Black Sea macroalgae Cladophora vagabunda,Ceramium rubrum and Cystoseira barbata were studied. Fatty acids composition was analyzed by GC/MS. Total lipids content varied widely among the species and ranged between 0.66 and 0.98 g per 100 g fresh weight. Generally, saturated fatty acids were major components (62-71%), with 16:0 as the most abundant saturate (41- 57%). Total polyunsaturated FAs and monounsaturated FAs ranged from 28% to 38%. The green alga Cladophora vagabunda showed higher C18 PUFAs contents than did C20 PUFAs while for red alga Ceramiumrubrum the trend was opposite. Cystoseira barbata belonging to the group of brown algae showed similar amounts of C18 and C20 PUFAs contents. Cladophora vagabunda was rich in linoleic acid and Ceramiumrubrum in arachidonic acid (AA) while Cystoseira barbata was rich in both linoleic acid and eicosopentaenoic acid. All of the studied species had a nutritionally beneficial n6/n3 ratio (1.24-2.84:1).

Comparison of heavy metal concentration of some marine fishes from Black and Aegean Seas

Abstract Major part of healthy human diet consist of marine fish and seafood products. And it is not surprising that there are numerous studies based on metal accumulation in various fish species. Fish may also be used for heavy metal monitoring programs of marine environments due to their easy sampling, sample preparation and chemical analysis. Concentrations of lead, cadmium, nickel, copper, manganese, zinc, iron, chromium, total mercury and total arsenic were determined in edible part of two commercially valuable fish Greek aquaculture species European sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) purchased from Bulgarian market during 2011. The concentration of metals was measured by atomic absorption spectrophotometry (AAS). The concentration of the heavy metals in examined fish species ranged as follow: Pb 0.008 - 0.013; Cd 0.0017 - 0.022; Ni 0.007 - 0.012; Cu 0.054 - 0.115; Mn 0.043 - 0.09; Zn 0.14 - 0.15; Fe 0.17 - 0.19; Cr 0.05 - 0.07; Hg 0.11 - 0.13; As 1.6 - 1.8 mg kg-1 wet weight, respectively. The concentration of the heavy metals obtained from this study is compared with the results of a Black Sea bluefish (Pomatomus saltatrix) caught during the same year. The concentration of metals was significantly affected by the sampling site and fish species. Difference in the heavy metal concentration between European sea bass, gilthead sea bream is observed for Cu, Mn, Zn and Fe. Although, the heavy metals in the edible parts of the investigated fish were in the permissible safety levels for human uses.