Received: 7 December, 2009. Accepted: 4 April, 2010. Invited Review Dynamic Biochemistry, Process Biotechnology and Molecular Biology ©2011 Global Science Books Nutritional Value of Gilthead Sea Bream and Sea Bass Constantina Nasopoulou 1 • Haralabos C. Karantonis 2 • Ioannis Zabetakis 1* 1 Laboratory of Food Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimioupolis, 157-71 Athens, Greece 2 Department of Science of Food and Nutrition, School of the Environment, University of the Aegean, 2 Metropoliti Ioakim Str., 814-00, Myrina, Lemnos, Greece Corresponding author: * izabet@chem.uoa.gr ABSTRACT Fish and fish oil have a high nutritional value and protect against cardiovascular diseases. Given the intrinsic difficulties in sustaining the availability of wild fish, the industry has moved, over the past three decades, towards establishing aquaculture units where fish are produced under controlled conditions. Sea bass (Dicentrarchus labrax) and gilthead sea bream (Sparus aurata) are the two most commercial aqua cultured species in Europe. In this mini review, the studies of the nutritional value of these two species are evaluated in terms of contents of -3 fatty acids and micro constituents of fish lipids with a particular focus on their ability to inhibit or not the initiation of atherogenesis. Platelet Activating Factor (PAF), a key trigger molecule in atherogenesis, and PAF antagonists, that are present in fish, play a crucial role in inhibiting the formation of atheromatic lesions. The diet of aqua cultured fish is also evaluated for its contents of -3 fatty acids and its capacity to inhibit PAF activity. New trends are presented towards modifying this diet to produce fish with a higher nutritional value. _____________________________________________________________________________________________________________ Keywords: Farmed fish, -3 fatty acids, micro constituents, antiatherogenic properties CONTENTS INTRODUCTION........................................................................................................................................................................................ 32 COMPOSITION OF MUSCLE, FAT CONTENT, FATTY ACID PROFILE .............................................................................................. 33 Fat ............................................................................................................................................................................................................ 34 Fatty acids................................................................................................................................................................................................ 34 Factors affecting muscle composition and fat deposition ........................................................................................................................ 36 FISH LIPID MICRO CONSTITUENTS ..................................................................................................................................................... 37 PAF antagonists ....................................................................................................................................................................................... 37 ANTIATHEROGENIC PROPERTIES OF FISH LIPIDS ........................................................................................................................... 38 CONCLUSIONS ..................................................................................................................................................................................... 38 REFERENCES............................................................................................................................................................................................. 38 _____________________________________________________________________________________________________________ INTRODUCTION Consumers consider organoleptic properties (e.g. flavour and texture), freshness and nutritional value as the main signs of quality when selecting fish. The nutritional value of fish is directly related to its chemical composition that is dependant upon many factors such as species, age, size (Iverson et al. 2002; Grigorakis 2007), sex, spawning (Gri- gorakis 2007), environmental factors such as season (Grun et al. 1999; Iverson et al. 2002), water temperature (Grigo- rakis 2007), salinity (Roche et al. 1989), changes in photo- period (Gines et al. 2004), geographical origin (Nettleton 1985; ckman 1989; Saito et al. 1999) and feeding history especially concerning farmed fish (diet composition and feeding ratio) (Huss 1988). Fish flesh flavour depends on fish tissue composition and also on harvesting and handling methods. For instance fatness and juiciness of fish flesh have both positively correlated with fat content in tissue (Izquierdo et al. 2003; Grigorakis et al. 2004). Furthermore, organoleptic differences have been described between the muscle textures of extensively and intensively farmed gilt- head sea bream (Orban et al. 1996). These differences con- sist of higher fatness, juiciness and fresh fish flavour, and lower fibrousness in intensively farmed fish. The main source of -3 polyunsaturated fatty acids (PUFAs) within our diet is from fish and fish oils, this is especially true for eicosapentaenoic acid (EPA) (20:5 -3) and docosahexaenoic acid (DHA) (22:6 -3) whose pre- sence is 10-100 greater in marine oil than in fruits, vegeta- bles, flaxy seeds, walnuts, and other vegetables (Simopou- los et al. 2000; Chen et al. 2003; Solfrizzi et al. 2005). Several studies demonstrated that fish oils actively benefit the symptoms of certain diseases such as cardiovascular diseases (Dyerberg et al. 1978, 1979; Simopoulos et al. 1997), cancer (erry et al. 2001), arthritis rheumatoid (James et al. 1997), diabetes II (Salmeron et al. 2001), neu- ropsychiatric diseases such as depression (Adams et al. 1996), maniodepression (Stoll et al. 1999) and schizophre- nia (Richardson et al. 2000). The nutritional value and the -3 fatty acids contents of several fish species, such as Atlantic salmon (Salmo salar L.), Atlantic cod (Gadus mor- hua L.), Atlantic herring (Clupea harengus) (Shearer 1994; Krogdahl et al. 2004), gilthead sea bream (Sparus aurata), sea bass (Dicentrarchus labrax) (Grigorakis 2007) and fresh water fish (Pickova et al. 2009) have been reviewed in other publications. Fish lipids also contain some micro constituents such as selenium and -tocopherol, whose beneficial effect has been attributed to their ability to act as antioxidants in humans (de Lorgeril et al. 2001), and plate- let activity factor (PAF, 1-O-alkyl-2-acetyl-sn-glyceryl-3- phosphocholine) antagonists, that possess antiatherogenic properties. In other words, these PAF antagonists inhibit the ®