Aquaculture Europe 2023

September 18 - 21, 2023


Add To Calendar 20/09/2023 15:45:0020/09/2023 16:00:00Europe/ViennaAquaculture Europe 2023ORGANIC MINERALS SUPPLEMENTATION AFFECT FILLET QUALITY OF FARMED GILTHEAD SEABREAM Sparus aurataSchubert 3The European Aquaculture Societywebmaster@aquaeas.orgfalseDD/MM/YYYYaaVZHLXMfzTRLzDrHmAi181982


 D. Kogiannou *,  A. Vasilaki ,  M. Kotsiri , Ch. Nikoloudaki , K . Grigorakis , I. Nengas

Institute of Marine Biology, Biotechnology and Aquaculture, Hellenic Centre for Marine Research, 46.7 km Athens-Sounion, Greece




Over the last decade, due to the continuou s growth of the aquaculture sector, marine-origin ingredients , i.e.  fish meal (FM) and fish oil (FO),  have been  partly  substituted with sustainably produced plant raw materials. The aforementioned changes in fish feeds composition affect the micronutrients balance resulting into lower levels of bioavailable minerals in aquatic feeds compared to fish natural diet , thus inorganic mineral supplements are commonly used to meet  fish requirements.

Gilthead sea bream (Sparus aurata ) farming is of great importance to European finfish mariculture accounting for  the 13% of its production value. This species is marketed mainly as whole fish and more recently as fillets.  Unfortunately, gilthead seabream fillets suffer from gaping, a texture deterioration phenomenon which leads to economic loss, because of the rejection by consumers due to its unappealing appearance.  Factors that have proven to be strongly associated with the fish propensity to gap, include the species, harvest or slaughter history, temperature during storage (Lavety et al., 1988; Sheehan et al., 1996; Robb et al., 2000) and diet (Kousoulaki et al., 2016).

Taking all the aforementioned into account, this study aimed to evaluate the impact of organic mineral feed inclusion on growth performance and fillet quality in terms of gaping occurrence, in gilthead seabream.

Materials and methods

Three isoproteic , isolipidic and isoenergetic diets were formulated: a control diet (Diet1) containing high FM (30% ), a  plant-based  diet  (Diet2)  containing low FM (12.5%) and a plant-based diet supplemented with organic minerals (0.18%) (Diet3) . These finishing diets were fed to triplicate groups of  gilthead seabream (253g  initial body weight) for a 92-day period. Water temperature maintained at 19οC in an open flow water system. Fish were fed by hand to apparent satiation  with the three diets. At the end of the trial, fish  were slaughtered by the commercial method (ice-killing) ,  individually weighted, packed with ice (0oC), and shipped to a commercial  fish  processing unit. After mechanical scale removal by drum, fish were machine filleted, weighted, ice-packed and transferred (within two hours) to the Hellenic Centre for Marine Research (HCMR). Individual fillets were assessed for their gaping according to a recently published gaping scale for Mediterranean fish species (Kogiannou et al., 2022), pH, water holding capacity (WHC), total composition, fatty acid profile, chemical freshness (K value), and total and soluble collagen content. The SPSS version 26.0 was used for the statistical analysis . Growth, p hysical and chemical parameters  are presented as mean± .  and comparisons among means were made using one-wa y analysis of variance (ANOVA).  The non-parametric χ2 test was applied to find statistical differences in the frequency of gap occurrence between the diets .  Differences were considered significant at the level of P<0.05.


 Fish growth parameters and feed intake were similar for all treatments, while  organic minerals inclusion had beneficial effect on fish fillet quality. Specifically, as shown in Figure 1.  distribution of gaping scores frequencies were found  to be  statistically different  among diets . In both Diet1 and 2,  increased high gaping scores incidence were observed  while flesh integrity remained quite intact in fish received Diet3. Additionally, fish fillet liquid losses and pH were not different in  gilthead seabream fed  the organic minerals supplemented diet compared to  Diet1 and 2.  No statistically significant differences were found  also  in the fillet composition of the fish fed the  experimental diets however, increased levels of n6 fatty acids were observed in both plant-based diets (Diet2 and 3). Finally, t he  total  collagen content  and collagen solubility  in gilthead seabream muscle , calculated  based on the hydroxyproline conten t, were found to  be  significantly affected by the diet composition and the organic mineral supplementation.


Dietary organic minerals included in  low fishmeal diet for  gilthead seabream significantly improved fillet quality  in  terms of  achieving  lower gaping incidence probably due to changes occurred in collagen content and solubility. The exact mechanism responsible for these observations remains to be identified.


The project is co-funded by Greece and the European Union under the Fisheries and Maritime Operational Program 2014-2020 (75% EMFF contribution, 25% National Contribution). Project title: “Imp roving of produced gilthead seabream and pagrus fillets by reduction of the gaping problem (PERFILLET)” (2019–2022).


Kogiannou , D., Kotsiri , M., & Grigorakis , K. (2022). A method to assess gaping in Sparidae species fillets. Aquaculture Research, 53, 689–693. https://doi. org/10.1111/are.15590

Kousoulaki , K., Mørkøre , T., Nengas , I., Berge, R. K., & Sweetman, J. (2016). Microalgae and organic minerals enhance lipid retention efficiency and fillet quality in Atlantic salmon (Salmo salar L.). Aquaculture, 451, 47-57.

Lavety , J., Afolabi , O. A., & Love, R. M. (1988). The connective tissue of fish. IX Gaping in farmed species. International Journal of Food Science and Technology, 23, 23–30. doi: 10.1111/j.1365-2621.1988.tb00546.x

 Robb, D. H. F., Kestin , S. C., & Warriss , P. D. (2000). Muscle activity at slaughter: I. Changes in flesh colour and gaping in rainbow trout. Aquaculture, 182(3-4), 261-269. doi: 10.1016/S0044-8486(99)00273-2

 Sheehan, E. M., O’connor , T. P., Sheehy, P. J. A., Buckley, D. J., & FitzGerald, R. (1996). Effect of dietary fat intake on the quality of raw and smoked salmon. Irish Journal of Agricultural and food research, 37-42.