Publication Date:
2021-07-14
Description:
Bacteria flora predominates the skin of freshly caught fish, and will invade the tissue of the fish immediately after catch. Two preservative methods (cold smoking and freezing) were used to store eighteen specimens of Chrysichthys furcatus harvested from River Niger at Cable-point, Asaba. Two specimens were randomly selected every day from the cold smoked specimens and on weekly basis from the frozen specimens for physical, chemical and biological examination for bacteria causing spoilage. Five bacteria isolates: Salmonella spp, Vibrio cholera, Escherichia coli, Staphylococcus aureus and Proteus vulgaris, were identified. Physical observation of the cold smoked fish after 24 hours showed the production of gas, off-odor, off flavour and slime formation. The colony forming units (CFU) of bacteria isolated from the fish immediately after harvest was 116 x 109 cfu/g. It increased to 268 x 109 cfu/g after 4 days of preservation, and to 64 x 109 cfu/g after four weeks of preservation. The Chi square (X2) analysis revealed that there was a significant difference between the bacteria load of frozen and cold smoked specimens. Free fatty acid value immediately after harvest was 0.90 %. It increased to 2.24 % after four weeks in the freezer and 2.35 % after four days of cold smoked storage. The Total Volatile Nitrogen profile at harvest time was 15.3 mgN/100g. It increased to 35.2 mgN/100g after four days, (for the cold smoked specimens) and 26.3 mgN/100g (for the frozen specimens) after four weeks. The peroxide and hydrogen ion concentrations followed the same increasing trend. The study revealed that freezer preservation was better than the cold smoked one. This is because bacteria proliferation was reduced and or halted in the frozen specimens, whereas it encouraged rapid bacteria growth in the cold smoked fish. The production of total volatile nitrogen (TVN), free fatty acid (FFA), peroxide value (PV) and hydrogen ion concentration (pH) was higher in the cold smoked specimens than in frozen ones, hence the cold smoked specimen exhibited shorter shelf life than their frozen specimens.
Description:
Includes:- 4 tables.;15 refs.
Keywords:
Fisheries
;
Chrysichthys furcatus
;
Nigeria
;
Niger R.
;
freshwater environment
;
Infestation
;
Fish storage
;
Microbial contamination
;
Chemical degradation
;
Chemical reactions
;
Biological damage
;
Damage
;
Processing fishery products
Repository Name:
AquaDocs
Type:
conference_item
,
TRUE
Format:
application/pdf
Format:
application/pdf
Format:
447-454
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