Does honey bee pollen as dietary supplement effectively preserve sea bream fillets during frozen storage?

Recently, the possibility to increase fish health, welfare, and fish storage stability through feed supplementation with natural additives or bioactive molecules has gained importance. Honey bee pollen (HBP) contains several interesting compounds such as polyphenols, which a new extractive technique called supercritic fluids extraction (SFE) seems to preserve. Indeed, SFE extract showed good antioxidant properties, high polyphenol content, radical scavenging activity, and reducing power. If these properties might act as antioxidants to preserve fish fillet quality during storage deserves to be investigated. Thus, our aim was to evaluate the effectiveness of honeybee extracts added to gilthead sea bream (Sparus aurata) feed formulation on the preservation of frozen fillet characteristics. Two levels of HBP (5% or 10%, P5 or P10 treatments, respectively) and its supercritical fluid extract (0.5% or 1%, E0.5 or E1, respectively) were included in the sea bream diet. After 15 days of adaptation, fish were fed for 30 days, then 9 fish per experimental group were sacrificed and filleted. Fillets were stored at −10 °C for 110 days and their fatty acids (FAs) were detected at slaughtering (day 0) and at the end of the storage (110 days). Analogously, lipid oxidation was assessed by conjugated dienes (CD, mmol hydroperoxides/100g meat) and thiobarbituric acid reactive substances (TBARS, mg MDA-eq./kg meat) quantification. The PROC GLM of SAS was used to analyse the obtained data with dietary treatment and storage time as fixed effects. Frozen storage caused a loss of polyunsaturated fatty acids (PUFA) of the n-3 series, while a higher content of saturated fatty acid (SFA) was found at day 110th (p < .05). Consistently, TBARS raised from 0.627 to 1.123 mg MDA-eq./kg fillet during storage (p < .05). E1 group was the most effective in oxidative damage mitigation, by exerting a specific protection on C18:3n-3, C18:4n-3, C20:1n-9, and C22:1n-11 FAs. Noticeably, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid content did not decrease along storage. In conclusion, administered HBP supercritical fluid extract at 1% seemed to slightly protect sea bream fillets from oxidative damages during long term frozen storage. Nevertheless, its action was limited to specific PUFAn-3 and few monounsaturated FAs. Due to the importance of finding natural bioactive products to improve fish metabolism, stress response, and fillet quality, further comprehensive studies are encouraged.