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.

Effect of frozen and refrozen storage of beef and chicken meats on inoculated microorganisms and meat quality.

The objective of this study was to investigate the effects of repeated freeze-thaw cycles on microorganisms, amino acid composition profile, chemical composition, mineral concentrations, water mobility, and fat of beef and chicken meats. Pure cultures of specific fungi and bacteria were separately injected into the minced meat. Apart from Pseudomonas, the total count of microorganisms significantly increased (P < 0.05) during refreezing treatment with the increase of storage period in both beef and chicken meats. During freezing treatment, the total count of Staphylococcus aureus, spore forming bacteria, and lactic acid bacteria were meat-type dependent. In conclusion, freeze-thaw cycles increased the microbial counts and decreased the water holding capacity, amino acids, and mineral concentrations of beef and chicken meats.

Nitroso-hemoglobin-ginger conjugates effects on bacterial growth and color stability in a minced beef model.

This study aims to enhance the color and microbiological qualities of a raw beef using natural ingredients. Nitroso-hemoglobin (NO-Hb) integrated with vitamin C (VC), calcium lactate, and ginger complexation were used as natural inhibitors against the growth of aerobic and pathogenic bacteria, namely (Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Salmonella. NO-Hb inhibited E. coli, S. aureus, and Salmonella, and enhanced the color stability more than nitrite in the minced beef model. After the multiexponential analysis of relaxation decays, the water component (T2b) was analyzed using the low-field NMR. The results indicated that, at the 7th d of cold-storage the third component (T2) was detected. Significant correlations were observed between T21 and T22 relaxation times and water-holding capacity in minced beef, implying that the LF-NMR measurements could be an efficient method for the determination and prediction of beef freshness. NO-Hb- ginger mixture, as a novel ingredient, could be used instead of nitrite in terms of meat safety.

Effect of incorporation of Cyperus rotundus L. rhizome powder on quality attributes of minced beef meat.

The primary objective of this study was to investigate the biological effectiveness of C. rotundus rhizome powder (CRRP) in improving the quality, storability, and safety of minced beef meat. CRRP was analyzed for its flavonoid and polyphenol content, antioxidants and antimicrobial activity, and its effect on the chemical properties, microbiological and sensory quality of minced beef meat. The results revealed that CRRP had a flavonoid and polyphenol contents of 24.30 mg CE/g and 353.10 mg GAE/g, respectively. The aqueous extract of CRRP showed inhibition zones of 16.3 and 11.7 mm against E. coli and S. aureus, respectively. The CRRP exhibited greater increase in TRPA, chelation of Fe2+ ions, and scavenging of H2O2 with the increase in CRRP extract concentration. Incorporation of various concentration of CRRP in minced beef meat significantly affected the physicochemical properties, microbial load, and sensory quality of the product. The effect was concentration dependent, and the highest level of CRRP (5 %) was more effective in retarding microbial growth and reducing peroxidation, but it negatively affected the sensory quality of the product. Therefore, CRRP at 2.5 % concentration was recommended as a functional additive to preserve minced meat.

Ripening of Sudanese Braided (Muddaffara) Cheese Manufactured from Raw or Pasteurized Milk: Effect of Heat Treatment and Salt Concentration on the Physicochemical Properties.

The objective of the study was to investigate the interactive effect of heat treatment (raw or pasteurized milk), ripening in salted whey (SW) and storage period for up to 3 months on the physicochemical properties of Sudanese braided cheese (SBC). Braided cheeses were manufactured from raw (BCRM) and pasteurized (BCPM) milk and ripened in SW (0%, 5%, and 10% salt) for up to 90 days. All the treatments significantly (P ≤ 0.05) affected the physicochemical characteristics of SBC. The total solid, protein, and fat contents of BCRM or BCPM decreased (P ≤ 0.05), whereas their TA, SN, and salt contents increased significantly (P ≤ 0.05) as storage period and the salt level of the whey were elevated. Both FRI and SRI of BCRM and BCPM increased with the increase in storage period and the salt level of the whey. For SN, FRI, SRI, pH, and moisture contents the magnitude of the change was more pronounced in BCRM than in BCPM, while for protein, fat, salt, and TS contents, the opposite was true; that is, the magnitude of the change was more pronounced in BCPM than in BCRM. Further studies are required to standardize muddaffara cheese manufacturing procedure particularly in rural areas.

Storage and Display-Life Characteristics of Beef as Affected by Prerigor Pressurization.

Top round cuts were obtained from sixteen sides of utility cows. Eight sides were randomly assigned as control (CON) and the remainders were prerigor pressurized (PRP) at 15,000 psi for 2 min. The top round from each side was divided into 4 wholesale cuts, vacuum packaged, heat-shrunk and randomly assigned to 0, 3, 5 or 7 weeks of storage at -1.6±1°C. Upon completion of each storage interval, wholesale cuts were removed from the storage area, purge losses determined and samples for microbial counts obtained. Two boneless steaks were prepared from each wholesale cut and displayed for 5 d at 1-3°C with 1076 lux fluorescent lighting for 12 h each day. Purge loss differed (P<0.05) only for the 5th week of storage. Wholesale cuts from PRP and CON had similar microbial counts at 0 and 3 weeks, while CON samples had higher microbial counts at 5 and 7 weeks. For all storage intervals, muscle color of the displayed steaks was improved (P<0.05) for the first 4 d of the display period by the PRP treatment. PRP steaks were consistently less discolored for all storage intervals. PRP improved the overall desirability of the displayed steaks throughout the experiment. Steaks prepared from PRP and CON wholesale cuts had the same microbial counts at 0 and 3 weeks of storage while CON steaks had higher and in most instances significantly higher microbial counts for 5 and 7 weeks. PRP had no apparant detrimental effects on the storage or display-life characteristics of meat, instead it beneficially influenced most of the parameters that were examined in this experiment.