The present study was developed as a part the research project “Potential use of wine and beer bagasse as sources of functional ingredients and nutrients in feeds for aquaculture’’ (UBAGALAC, P20-00923) jointly funded by the Junta de Andalucia and the EU.
Material & Methods
The objective of this preliminary study was to test different biological effects of grape pomace and a wine by-product concentrated extract (Olpheel® Anti-Ox, OAO, Laboratoires Phodé, France) in feeds for juvenile European sea bass (Dicentrarchus labrax), on three different aspects: the oxidative status of fish, functionality of intestinal microbiota, and oxidation of fillets after fish sacrifice and one week storage. A total of 180 juvenile sea bass with average body mass of 46.35 ± 0.12 g were equally divided into 9 under controlled environmental conditions of salinity (37 ‰), temperature (19°C) and photoperiod (10L:14D). Experimental feeds (control diet, a diet supplemented with 80 ppm of OAO) were prepared using a lab-scale extrusion machine. Daily ration was offered till visual satiety distributed in 4 daily meals.
Results
A significant effect of OAO on the microbial profile was evidenced as a reduced biodiversity (a lower number of functional groups) when compared to that of fish fed on the control diet, as well as by a higher functional richness (a higher intensity of the response that could be related to a higher number of specific OTUs (Operational Taxonomic Unit). This effect was not observed in the group fed the grape pomace diet. Significantly higher levels of superoxide dismutase (SOD) were measured in the groups of fish receiving OAO and grape pomace compared to the control. The significantly higher levels of SOD can be the net result of an increased expression of genes coding such enzyme. Regarding oxidation in stored fillet of the fish, a protective effect against oxidation was evidenced in samples of fish fed on diet including grape pomace and OAO when compared to those fed on the control diet
Those results together suggest that incorporating wine by-products like grape pomace or concentrated extract rich in oligoprocyanidins like Olpheel® Anti-Ox to sea bass diets, could improve their antioxidant status and fillet quality. Further studies should then be carried out with higher dosage, and to further understand the effect of such a product on diversity and functionality in microbiota and its consequences.