Effects of agar films incorporated with fish protein hydrolysate or clove essential oil on flounder (Paralichthys orbignyanus) fillets shelf-life

Abstract

22This study evaluated the effect of protein hydrolysate (PH) and clove essential oil (CEO) on 23 agar film properties and the shelf-life improvement of flounder fillets. Firstly, Argentine croaker 24 muscle protein was alkali-solubilised and recovered to obtain a stable substrate. This substrate 25 was hydrolysed to 20% degree of hydrolysis, by Alcalase (A20) and Protamex (P20). The 26 molecular weight (MW) distribution, amino acid and in vitro antimicrobial activity of these 27 hydrolysates were tested. Agar films were prepared with and without (control) incorporation of 28 PH (A20 hydrolysate) or CEO characterised by mechanical properties, water vapour 29 permeability, solubility and optical properties. The microbiological, physical and chemical 30properties of flounder fillets coated with these films were monitored during storage at 5°C for 31 15 days. Compared to P20, A20 hydrolysate possessed lower MW, higher hydrophobic amino 32 acid content and the most effective antimicrobial activity against selected pathogens, such as 33 Staphylococcus aureus, Yersinia enterocolitica, Aeromonas hydrophila, Debaryomyces hansenii 34and Listeria innocua. The presence of PH increased the water solubility, water vapour 35 permeability, elongation at break and yellowness of the films. The CEO films possessed less 36 transparency than PH films and control films, due to the presence of oil in the formulations. 37Fillets covered with PH and CEO films, especially the latter, presented lower total volatile bases 38and pH values, and delayed considerably the growth of H 2 S-producing microorganisms 39 compared to the control films. The CEO might be used as a natural biopreservative to extend the 40 flounder shelf-life. However, further studies are necessary, to assess the antimicrobial effect of 41 PH when used as food packaging. 42 43

Biodegradable carboxymethyl cellulose–polyvinyl alcohol composite incorporated with GlycyrrhizaGlabra L. essential oil: Physicochemical and antibacterial features

“…According to Table 2, the thickness of the control film was equal to 0.148 mm. The thickness slightly increased by addition of 0.25% and 0.50% GGEO into the (da Rocha et al, 2018;Wu et al, 2017).…”

Natural Preservatives for Extending the Shelf‐Life of Seafood: A Revisit

“…Another strategy to integrate EOs or plant extracts into food is via their incorporation into films for wrapping (termed active packaging), in which the active components can be gradually released to perform their function in the target food. For example, the biochemical (TVB‐N), physical (pH and weight loss), and microbiological quality of flounder ( Paralichthys orbignyanus ) fillets packaged in agar film incorporated with fish protein hydrolysate (FPH) (0.5 g FPH/g agar) were slightly lower than samples packaged with the film containing clove EO (0.5 g EO/g agar), although both films extended the shelf‐life of the fillets (da Rocha et al., ). In another example, the shelf‐life of rainbow trout wrapped using 8% gelatin films with and without laurel EO (1% v/m) was extended to 22 and 20 days, respectively, versus 15 days for the control (without gelatin films), during storage at 4 °C (Alparslan, Baygar, Baygar, Hasanhocaoglu, & Metin, ).…”

Shelf-Life Extension of Refrigerated Turbot (Scophthalmus maximus) by Using Weakly Acidic Electrolyzed Water and Active Coatings Containing Daphnetin Emulsions

“…H 2 S-producing bacteria (mainly Shewanella putrefaciens) and Pseudomonas spp. are the common SSOs in some marine fish and fish products during refrigerated storage (29,30). The population of the two microbial communities increased with storage time in all samples (Figures 1B,C), which showed similar trends as that of TVC.…”