Evaluation of the Freshness and Shelf-Life of Fresh and Chilled Mackerel (Scomber Spp.) and Horse Mackerel (Trachurus Spp.), Marketed in Luanda (Angola) and in Faro (Portugal)

Abstract

A methodology based on sensory analysis (Quality Index Method, or QIM) and a set of physicochemical parameters (pH, total volatile basic nitrogen (TVB-N) content, peroxide value (PV), and the concentration of thiobarbituric acid reactive substances (TBARS)) was used to evaluate the degree of freshness/quality and estimate the shelf life of fresh and chilled mackerel and horse mackerel, marketed in Luanda (Angola) and in Faro (Portugal). Mackerel (n = 25) and horse mackerel (n = 27) were stored and chilled on ice at 5 ℃ during 11–13 days and sampled regularly. On day 7, the sensory panels in Faro and Luanda rejected both species. Moreover, TVB-N contents in mackerel (37.34 ± 2.61 mg N/100 g in Luanda and 37.57 ± 1.17 mg N/100 g in Faro) and horse mackerel (30.11 ± 3.45 mg N/100 g in Luanda and 49.12 ± 0.84 mg N/100 g in Faro), were above the values stipulated in EU regulation (25-35 mg N/100 g). In addition, concentration of TBARS (25.12 ± 7.76 µg MDA/g in Faro and 10.51 ± 1.01 µg MDA/g in Luanda for mackerel and 11.50 ± 2.18 µg MDA/g in Faro and 7.44 ± 2.80 µg MDA/g in Luanda for horse mackerel) were above the suggested limit of 7–8 µg MDA/g. Therefore, based on these results and the other quality parameters evaluated in this study, mackerel and horse mackerel marketed in Luanda and in Faro should be stored with ice at 5 ℃ to obtain a maximum shelf-life of up to 7 days.