A comprehensive approach to assessment of the quality and shelf-life for retail fresh hake (Merluccius australis) during Chilled Storage

• TVB-N was considered the best freshness indicator in Chilean southern hake. • Extended shelf-life up to day 8 (national) and day 4 at 4 °C (international markets). • Increment of volatile bases corresponds to the increase in TMA levels. • Results could indicate not adequate retail practices that affect fish freshness. • Use slurry or flake ice would be enough to extend shelf-life of fish products. The Chilean southern hake, Merluccius australis , is one of the most important marine fishery resources in Chilean Patagonia. The aim of this study was to investigate the compositional changes in M. australis due to alterations in its volatile composition and other parameters over a period of 23 days in order to evaluate its shelf-life storage at chilled temperatures using fish quality parameters. The samples were bought from the main seafood market in Valdivia city, located in southern Chile. First, an organoleptic evaluation of sensory properties was conducted. Then, pH, total volatile basic nitrogen contents (TVB-N), and trimethylamine (TMA) levels, histamine concentration, and total viable counts (TVC) levels as a microbiological parameter were determined. A repeated measures generalized linear model (GLM) and Duncan's test as post hoc test were used to analyze data. The data revealed that pH levels were always over 7 from day 0 (7.31) to 23 (7.72), which could indicate the prevalence of good but not highest quality in specimens at day 0. No significant differences ( P = 0.558) in pH values were obtained during all days of storage at lower than 4 °C. Additionally, the study found a progression of volatile bases levels where TVB-N and TMA levels, increased significantly after 7 days of storage in both cases and exceeded the allowable limit to the family Merlucciidae at day 15 and at day 9, respectively. Both could be considered as reliable indicators by freshness in Chilean southern hake under the present scenario, showing the first empirical results at long storage. On the other hand, histamine concentration was below the allowable limit in fish. And total viable counts (TVC) levels as a microbiological parameter, fluctuated and increased gradually during the first 9 days (from 4.18 log cfu/ml to 4.91 log cfu/ml), and increasing significantly after 15 days (5.42 log cfu/ml) and 23 days (6.32 log cfu/ml) of storage, but did not exceed the spoilage regulation thresholds. These findings emphasize the importance of implementing good practices and improving knowledge in the retail market and to consumers to avoid lengthy storage of fresh fish before consumption, to prevent foodborne illnesses.