Efeito dos revestimentos à base de carragenana extraída de Hypnea pseudomusciformis na vida útil de filés de salmão (Salmo salar) refrigerado.

Abstract

The preservation of refrigerated fish is an economic and sanitary challenge due to its high susceptibility to microbial growth and chemical reactions that impair sensory and nutritional quality. Edible coatings based on marine polysaccharides have been proposed as physical barriers and delivery systems for preservative agents. Among them, carrageenan extracted from red algae stands out for its availability, biocompatibility, and good film-forming properties. This study evaluated the effect of carrageenan-based edible coatings, extracted from the macroalga Hypnea pseudomusciformis, on the shelf life and quality of salmon fillets (Salmo salar) stored at 0 °C for 18 days. The carrageenan was obtained by aqueous extraction (steps at 25 °C and 80 °C), ethanol precipitation, dialysis, and lyophilization, and the polymer solutions were prepared at concentrations of 1.0, 1.5, and 2.0% (w/v), with and without Tween 80. Preliminary wettability assays (spreading coefficient Ws) guided the selection of the applied formulation. The 1.0% (w/v) solution without surfactant showed the best balance between viscosity, spreading ability, and repeatability, and was selected for application to the fillets. FTIR analyses and surface tension measurements were performed. During storage, pH, TVB-N, TMA-N, TBARS, total aerobic count (TPC), and K-value by HPLC were monitored. The coating delayed nucleotide degradation kinetics, reducing the increase in K-value by ~25% and keeping the fillets within the moderate freshness range (K < 40%) for 15 days, compared to 12 days in the control. In parallel, TPC in coated fillets remained below 7.0 log10 CFU/g until day 15, while the control exceeded this limit on day 12, indicating a 3-day extension in microbiological shelf life. FTIR spectroscopy confirmed the high purity and reproducibility of the extracted carrageenan. These results support the potential of H. pseudomusciformis carrageenan as a promising physical barrier for the preservation of refrigerated fish.