Effects of fuel sources on organoleptic characteristics, polycyclic aromatic hydrocarbon concentration and shelf life of smoked Nile tilapia (Oreochromis niloticus)

This study assessed the effect of four different fuel sources on the organoleptic properties, polycyclic aromatic hydrocarbon concentration (PAH) and shelf-life of smoked Nile tilapia (Oreochromis niloticus). Dry wood of Gmelina (Gmelina arborea), Parkia (Parkia biglobosa), Neem (Azadirachita indica) and charcoal were obtained around Ladoke Akintola University of Technology, Ogbomoso, Oyo state. Nile tilapia samples were smoked to complete dryness using the four fuel sources. Data were analyzed using descriptive statistics and ANOVA at p<0.05. The organoleptic assessment of smoked fish showed that there were slight differences in sensory score for colour, flavour, texture, taste and overall acceptability due to the difference in fuel source.  Fish sample smoked with Gmelina, had the highest score (3.27) for colour while charcoal smoked sample also had highest score of 3.27 for taste. Neem had the highest score of 3.27 and 3.09 for texture and flavour respectively. Overall acceptability of smoked fish samples were 2.73, 2.68, 2.61 and 2.14 for charcoal, Gmelina, Neem and Parkia respectively. Overall acceptability after being kept at room temperature for eight weeks was 2.82, 2.64, 2.46 and 1.46 respectively for charcoal, Gmelina, Neem and Parkia. There was however, no significant difference in the initial and final overall acceptability (p>0.05) after eight (8) weeks of storage. PAHs levels in smoked fish samples produced using the fuel sources was observed. Highest concentrations of 34.91±0.34 µg\kg was found in smoked Nile tilapia produced using Neem while Parkia, Gmelina and charcoal recorded 33.67±0.52 µg/kg; 19.57±0.50 µg/kg and 7.54±0.30 µg/kg respectively. Benzo[a]pyrene  (BaP) concentrations (1.37±0.32 µg\kg; 1.84±0.15 µg\kg; 7.89±0.59 µg\kg) for Gmelina, charcoal and Parkia smoked fish samples respectively were below the maximum acceptable limit of 10µg\kg established by the European commission. However, Neem wood with BaP of 11.07±0.58 µg\kg is considered not safe as fuel source for smoking Nile Tilapia.