Effect of frozen storage on the biochemical composition of five commercial freshwater fish species from River Nile, Sudan

Abstract

Postharvest processing and preservation of fish have great influence on fish quality and consumption. Freshwater fish in Sudan are facing problems related to bad handling and improper storage which reduce their quality. This study investigated the changes in the chemical composition, mineral contents, pH and acid value during storage (−18°C) of five commercial fish species (Bagras bayad, Lates niloticus L., Mormyrus casahive L., Oreochromis nilotica L., and Synodrontis schall) from the River Nile coast of Sudan. The fish species are rich in protein (17.22%–23.60%) but have low fat and ash contents. Frozen storage of the fishes for 45 days reduces their protein contents while the fat and ash contents were increased (p ≤ .05). Potassium and iron are the predominant major and trace minerals and their values were increased with storage period. The pH range from 5.74 (O. niloticus) to 6.24 (B. bayad) while acid value range from 0.02 (M. casahive) to 0.12 (L. niloticus). Both pH and acid values increased with storage period. In conclusion, storage of these fish species for up to 45 days did not adversely affect their nutritional value.

Changes of Volatile Flavor Compounds in Large Yellow Croaker (Larimichthys crocea) during Storage, as Evaluated by Headspace Gas Chromatography–Ion Mobility Spectrometry and Principal Component Analysis

“…More specifically, after 120 d, the AV, POV, p-AV, and CDV were 7.62 ± 0.14 mg/g, 23.67 ± 0.55 meq/kg, 2.33 ± 0.03, and 33.57 ± 0.89, respectively. This observed increase in the AV is also consistent with previous studies [ 24 , 25 ] and is closely related to the free fatty acid content [ 26 , 27 ]. Previously, it was reported that the oxidation of fish meat during storage causes the breakage of ester bonds, which releases a large amount of free fatty acids and increases the AV [ 28 ].…”

Assessment of cooking methods and freezing on the nutritional value and health risks of heavy metals in four fish species consumed in Douala, Cameroon

“…During defrosting, ice crystals perforate food membranes, leading to exudation of cellular contents [ 41 ] . Different results were obtained by Malik et al [ 42 ], who showed that freezing (−18 °C) increased significantly (P < 0.05) potassium content in Bagrus bayad . Akinwumi [ 50 ] reported that freezing and smoking increased significantly (P < 0.05) potassium content in Clarias gariepinus .…”

“…Different results were obtained by Aberoumand [ 41 ] who showed that during freezing, water content decreased in some Iranian coastal fish species. Malik et al [ 42 ] reported that during freezing at −18 °C, moisture content in Lates niloticus decreased significantly compared to that of raw fish. The addition of water during defrosting could explain the increase in water content of frozen fish [ 22 ] .…”

Gas-phase ion migration spectrum analysis of the volatile flavors of large yellow croaker oil after different storage periods

“…At 120 d, the AV, POV, p -AV, and CDV were 3.77 ± 0.14 mg/g, 75.16 ± 0.85 meq/kg, 1.94 ± 0.07, and 43.29 ± 0.23, respectively. The increased AV is closely related to the free fatty acid content ( Malik et al, 2021 ). It has been reported that the oxidation of fish oil during storage causes the breakage of ester bonds, releasing a large amount of free fatty acids that increase the AV ( Crexi et al, 2009 ; Zhang et al, 2021 ).…”