Effect of Traditional smoking Method on Nutritive Values and Organoleptic Properties of Sarotherodon galilaeus and Oreochromis niloticus

Fish deterioration or spoilage is one of the greatest problems facing the fishing industry in Nigeria, and since ancient times, smoking has been used to preserve fish products and improve their taste, aroma and colour. The present study was carried out to determine and compare the effects of traditional smoking kiln on nutritional properties and sensory characteristics of Sarotherodon galilaeus and Oreochromis niloticus. A drum type smoking kiln was used for fish smoking. Raw and smoked fish samples were subjected to nutritional analysis and sensory evaluations. Nutritional analysis showed that the crude protein value of smoked O. niloticus (47.69 + 0.13%) was significantly (P<0.05) lower than the smoked S.galilaeus (50.12 +0.31%) while the crude fat values of S.galilaeus was slightly higher than the O. niloticus. The value of nitrogen free extract of S.galilaeus was higher than the value of O.niloticus with mean values of 18.00+ 0.02% and 0.32±0.01% recorded respectively while the metabolizable energy value of S. galilaeus was significantly (P<0.05) higher than O.niloticus . Sensory evaluation results revealed that smoked S. galilaeus was better in terms of juiciness and overall acceptability while O. niloticus had higher values in term of flavour, tenderness and texture. Based on the results of the study, smoked S. galilaeus and O. niloticus were nutritionally comparable. The results also showed that traditional smoking method is an important preservation method which could enhance the nutritive values of fishes and possibly reduce post-harvest losses.Keywords: Proximate composition, Sarotherodon galilaeus, Oreochromis niloticus, smoking, sensory evaluation

Effect of Calcium (Hardness of Water) on the Uptake of Ciprofloxacin in Bath-Medicated African Catfish (Clarias gariepinus)

Seventy -two catfishes weighing between 200 and 250g (and distributed into 3 groups) were subjected to bath medication with ciprofloxacin at 25mg/litre of water. Medicated water of each group (24 catfishes/group) had the same pH of 6.6, after adjustment using sodium carbonate, but different levels of calcium hardness .Group A water had 12.5mg/litre of calcium hardness, while for groups B and C, the levels of the calciumhardness were adjusted to 212.5mg/litre and 412.5mg/litre respectively using calcium chloride. Samples (blood, liver, kidney and muscle) were taken from two randomly selected fishes in each group within 8hours of exposure to ciprofloxacin. These were taken at 0 h, 0.5h, 1 h, 2 h, 4 h, and 8 h and were preserved at - 0.5°C, prior to processing and drug extraction. Ciprofloxacin level was quantified by ELISA. The seraarea under the curve (AUC) values of groups A, B and C were 17,938.13 ìg.hr./L, 18,883.75 ìg.hr./L and 12,273.75 ìg.hr./L respectively, showing that at the highest concentration of calcium ions in medicated water (as seen in group c ) level of the absorption .of ciprofloxacin will be reduced , hence reduced bioavailability There was also a direct linear relationship between the AUC values for tissue and the level of calcium hardness of water. This study therefore suggests a need to strongly consider the influence of corechemical parameters of fish culture water such as hardness, alkalinity and pH, as these can reduce efficacy or increase toxicity of drugs that are administered to fish by bath method