EFFECT OF PROCESSING ON BACTERIAL POPULATION OF CUTTLE FISH AND CRAB AND DETERMINATION OF BACTERIAL SPOILAGE AND RANCIDITY DEVELOPING ON FROZEN STORAGE

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

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.

Influence of energy removal rate on the quality of minced meat from undersized crawfish during frozen storage

Abstract

Undersized crawfish have little economic value and are often discarded. Producing crawfish minced meat (CMM) from undersized crawfish and using an appropriate freezing technique may enable an economically viable market. The objective of this research was to evaluate the effect of the energy removal rate using two techniques, cryogenic freezing (CF) and air blast freezing (BF), on CMM’s quality during frozen storage. CMM was separated into two batches; one batch was cryogenically frozen with liquid nitrogen and the other batch was frozen with an air blast freezer. CMM batches were frozen and stored at − 18 °C. They were analyzed for moisture content, color, pH, and lipid oxidation during 180 days of storage. The CMM yield was 64.67% of the total crawfish weight. Cryogenic freezing achieved the highest freezing rate. Cryogenically frozen CMM showed 22% less lipid oxidation than CMM frozen by air blast freezing at 180 days of storage. This study showed that CMM could be mechanically produced from undersized crawfish and freezing techniques with high energy removal rate could better maintain quality attributes for CMM during frozen storage.

Graphical abstract