Abstract
Freshness is considered one of the most important parameters to judge the quality of most fish products. In the current study, the seasonality effect on the freshness profile of different economic fish species was evaluated for the first time, using three different approaches (sensory: Quality Index Method (QIM) and European (EC) Scheme; physical: Torrymeter (TRM) values; and microbiological analyses: Total Viable Counts (TVC) and degradative bacteria). Over a year, individuals of farmed fish Sparus aurata and Dicentrarchus labrax, as well as the wild fish Trachurus trachurus, Scomber colias, and Sardina pilchardus, were sampled seasonally for the evaluation of their freshness profile over 10 days on ice. In general, data showed an increase in QIM values, a decline in TRM, and an increase of spoilage bacteria throughout the storage time, revealing a clear temporal degradation of the quality of the fish. Additionally, some signs of seasonality effect could only be observed for some species. For example, the seabass D. labrax showed lower numbers of degradative bacteria in winter than in the other seasons, suggesting a high potential to be marketed in a fresher condition, especially during that season. On the other hand, S. colias showed higher freshness scores (i.e., higher TRM values in spring and autumn and lower numbers of bacteria in summer) from spring to autumn. However, from the five studied species, S. colias presented the lowest freshness values, indicating a higher fragility of this species. This information is extremely relevant for consumers and retailers that want to invest in higher quality products, as they would thus be able to choose certain species in detriment of others. Additionally, obtained data showed that farmed species reached day 10 of storage time with lower values of QIM and microbial counts (cfu), as well as higher values of TRM, in relation to wild species. These results reinforce the idea that farmed fish can, under proper conditions, present high quality/freshness profile.
Highlights
Fisheries and aquaculture production have a significantly lower carbon footprint compared to that of chicken, pork, and beef production
A significant interaction between time and seasons was observed for both parameters (QIM: 2-way ANOVA on ranks, F(9,80) = 6.056 and p = 0.000002; EC scheme: 2-way ANOVA on ranks, F(9,80) = 3.44 and p = 0.001)
Data obtained in the current study showed that farmed species that reach day 10 of storage time presented lower values of Quality Index Method (QIM) and microbial counts and higher values of TRM compared with the wild species
Summary
Fisheries and aquaculture production have a significantly lower carbon footprint compared to that of chicken, pork, and beef production. Fish has rapid growth and relatively low production cost, contributing to a healthy diet due to its high-quality protein, other essential nutrients such as omega 3-fatty acids, and low-fat content. Due to these characteristics, fish products have shown increasing demand, with a contribution of 60% of the world protein supply. Culture temperature may affect the amount of deposited lipids, as well as the fatty acid profile. These changes could affect the nutrient demands of the fish, as well as their organoleptic attributes [5]. Considering that fish is highly perishable (among other reasons, due to their fragile fatty acid composition, high content of water, and endogenous enzymes), loss of quality/freshness is very rapid and depends on a complex process where physical, chemical, and microbiological reactions are involved [1]
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