Nutrients and Microbial Evaluations of Ginger Pre-treated Smoke-dried African Lungfish (Protopterus annectens Owen, 1883)

Abstract

The nutrients assay and microbial evaluation of ginger pre-treated smoked African lungfish (Protopterus annectens) stored for a week at room temperature were studied. Forty five fish samples weighing 1.0 kg each were purchased, killed, eviscerated and washed thoroughly under tap water and grouped into three treatments of fifteen fish each coded as treatments A, B, and C respectively. Fish in treatment  A were immersed in 5% brine without spice (ginger) pre-treatment served as the control, treatment B was soaked in mixture of 5% brine and 2.5% ginger extract while treatment C was immersed in a solution containing mixture of 5% brine and 5% ginger extract. Each batch was smoke-dried for a period of six hours. The samples from each batch were subjected to proximate composition within 48 hours and microbial analysis on 7th day of storage at ambient temperature. The results of the proximate analysis showed a significant difference (P<0.05) among the pre-treated samples. Sample A had the highest moisture content (11.85%). The highest concentration of crude protein was obtained in sample C (63.94%) while samples B and A recorded the values of 63.8 and 59.51% respectively (p<0.05). The highest crude fat concentration was obtained in sample C (8.46%), followed by sample B (8.44%) and the least was recorded in sample A (5.78%). The microbiological analysis showed that sample A (control) favoured the proliferation of microorganisms such as E. coli, Staphylococcus aureus, Bacillus spp and Micrococcus spp more than samples treated with ginger extract. The overall microbial population ranged between 3.0x104 and 2.0x105 which are within the safety limit (≤ 105 cfu/g) for total bacterial plate count for microbiological food. This result therefore has indicated that the use of brine with ginger extract could be suitable for prolonging the shelf-life of smoked lungfish without negative effects on the nutrients composition and storage quality under ambient conditions.