Veselina Panayotova

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.

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.