POLYCYCLIC AROMATIC HYDROCARBONS AND NUTRIENT COMPOSITION OF Clarias gariepinus AND Oreochromis niloticus PROCESSED WITH DIFFERENT FUEL TYPES

Abstract

This study evaluated the quality and safety of two fish species, Oreochromis niloticus and Clarias gariepinus,
processed using various fuel types: firewood (Anogeissus leiocarpus), maize cob, charcoal, and a solar tent dryer.
A total of 80 samples, comprising 40 Oreochromis niloticus and 40 Clarias gariepinus, were purchased from
fishermen at the Zobe reservoir in Dutsin-Ma, Katsina State, Nigeria. The fish samples were processed, smokedried,
and analyzed for polycyclic aromatic hydrocarbons (PAHs), proximate composition, free fatty acids (FFA),
and peroxide value (PV). Proximate composition was assessed at week 0 and after 12 weeks of storage. Twenty
PAHs were identified; significant differences (P < 0.05) were observed in naphthalene, benzo(k)fluoranthene, and
benzo(a)pyrene, with solar-dried fish showing unexpectedly elevated levels. Initial proximate composition (week
0) did not differ significantly among the treatments except for ash content, which was significantly higher in maizecob-
smoked fish compared to solar-tent-dried fish, with the highest individual value (15.05±1.65%) observed in
charcoal-smoked O. niloticus. After 12 weeks of storage, significant differences emerged between the two fish
species for all parameters except crude lipid. Moisture, crude lipid, and crude protein contents also varied
significantly among the fuel types. Free fatty acids (FFA) ranged from 0.48 mg/g in solar-dried O. niloticus to 1.08
mg/g in maize-cob-smoked C. gariepinus, and were significantly higher in C. gariepinus. The peroxide value (PV)
ranged between 2.16 meq/kg in charcoal-smoked O. niloticus and 3.61 meq/kg in solar-dried C. gariepinus, but
was not influenced by fuel type. The results revealed that both fish species and fuel types significantly influenced
the nutritional profile and contaminant accumulation of processed fish; while nutritional levels remain high, the
elevated PAH contents pose critical food safety concerns.