Influence of ice-to-fish ratio on spoilage kinetics, microbiological quality, and shelf life of refrigerated farmed gilthead sea bream (Sparus aurata).

The preservation of fish quality during post-harvest storage remains a major challenge for the aquaculture industry, particularly in Mediterranean countries where chilled storage is the most commonly used preservation method. This study evaluated, for the first time in Algeria, the effect of different ice-to-fish ratios on the quality and shelf life of farmed gilthead sea bream (Sparus aurata) during refrigerated storage. Fish were stored at three ice-to-fish ratios (1:2, 1:3, and 1:4) and monitored over 16 days. Sensory quality, total viable counts (TVC), H₂S-producing bacterial counts, pH, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA) were determined at regular intervals. Storage time significantly affected all quality parameters (p < 0.05), with progressive sensory deterioration, microbial growth, and accumulation of spoilage metabolites observed in all treatments. However, the extent of quality loss depended on the ice-to-fish ratio. Fish stored at a ratio of 1:2 exhibited significantly lower TVC, H₂S-producing bacterial counts, TVB-N, TMA, and pH values than fish stored at ratios of 1:3 and 1:4 throughout storage. Pearson correlation analysis revealed strong positive relationships among all spoilage indicators, with the highest correlation observed between TVC and H₂S-producing bacterial counts (r = 0.997). Principal component analysis explained 98.9% of the total variance and clearly associated spoilage progression with increasing microbiological and biochemical deterioration. Shelf-life estimation based on the microbiological rejection limit (7 log CFU g⁻¹ TVC) indicated storage lives of 9.9, 7.6, and 5.6 days for fish stored at ice-to-fish ratios of 1:2, 1:3, and 1:4, respectively. Based on a TVB-N limit of 35 mg N 100 g⁻¹, estimated shelf life reached 17.3, 12.2, and 9.4 days, respectively. These findings demonstrate the importance of adequate icing for maintaining fish quality and provide the first scientific basis for optimising cold-chain management of farmed gilthead sea bream in Algeria.