Natural preservative biofilms based on Salicornia europaea extract and microalgae hydrolysates for European seabass fillets

Introduction: Fresh fish spoilage during refrigerated storage is a major challenge for both the
aquaculture industry and food safety. In response to restrictions on synthetic preservatives and
growing consumer preference for natural products, this study assessed aqueous biofilms based
on Salicornia europaea extract and a microalgae-blend hydrolysate (Nannochloropsis gaditana,
Chlorella sp., Schizochytrium sp.) as biopreservatives for European seabass (Dicentrarchus
labrax) fillets stored at 4 °C for 14 days.

Methods: Fillets were treated with distilled water (CT), ascorbic acid (ASC), S. europaea
extract (S), or microalgae hydrolysate (M) by spray coating and stored under industrial cold
conditions. Lipid oxidation, psychrophilic bacteria, texture, water-holding capacity, pH, and
color were monitored during storage up until 14 days post-mortem.

Results: S and M improved microbial and oxidative stability compared with CT and ASC. At
day 14, TBARS values remained below the consumption threshold in S and M, with 6.41 and
6.98 mg MDA/kg, respectively. Both treatments delayed psychrophilic growth, reduced texture
deterioration, and preserved colour attributes. M also retained 70.42% water-holding capacity at
day 14. Neither biopreservative negatively affected fillet appearance.

Conclusions: Biofilms containing S. europaea extract or microalgae hydrolysates effectively
slowed lipid oxidation and microbial spoilage in refrigerated seabass fillets without
compromising sensory quality. Their performance was comparable to, and in some cases better
than, ascorbic acid. These results highlight the potential of marine plants or algae extracts used as biopreservatives. These novel additives are a viable way for the diversification of conservation strategies in the food industry.