Microbial and some heavy metals analysis of smoked fishes sold in urban and rural markets in Akwa Ibom State, Nigeria

Abstract

Objective: The unhygienic nature of our local markets, including fish handlers, may contribute to the presence of microorganisms in smoked fish leading to food poisoning. Furthermore, heavy metals can find their way into the food chain through fish raising public health concerns. This study assessed the microbial load and some heavy metals in smoked fishes (bongafish and catfish) sold in urban and rural markets in Akwa Ibom State, Nigeria. Materials and Methods: Standard microbiological techniques and analytical procedures were used for microbial and heavy metals analyses, respectively. Results: The results revealed that all the smoked fish obtained from the two markets were contaminated with heavy metals and microorganisms. Zinc was the most frequently detected heavy metal in both fish types (catfish: 15.50 ± 9.99 mg/kg; and bongafish: 16.40 ± 12.28 mg/kg) obtained from urban market, while in the rural market, it was cadmium (catfish: 15.95 ± 10.15 mg/kg; and bongafish: 18.25 ± 7.15 mg/kg). The overall elemental concentrations of the heavy metals in the fishes were in decreasing order of Cadmium>Zinc>Nickel>Cobalt>Lead. The most predominant bacterial species in fishes from the urban market was Bacillus subtilis (7.5 × 104 ± 0.871 colony- forming unit/g) while Candida tropicalis (9.2 × 104 ± 0.105) was the most predominant fungal species. More bacteria and fungi were encountered in fishes from the rural market than from the urban market. The differences in the microbial loads from the two markets were not statistically significant (P > 0.05). Conclusion: There is a potential health risk of eating smoked fishes that are poorly stored or handled in the market as a result of heavy metal contamination and the presence of the pathogenic organism. Therefore, maintenance and enforcement of adequate sanitation practices in these markets should be encouraged to avert unpleasant health consequences.

Chemical hazards in smoked meat and fish

“…Several authors reported the presence of trace elements in smoked fish (Anigboro et al., 2011 ; Ibanga et al., 2019 ; Inobeme et al., 2018 ). Şireli et al.…”

“…The studies on the occurrence of heavy metals in smoked or grilled fish and meat reported in this section were mainly from Africa. Indeed, although some studies were from Turkey (Ersoy et al., 2006 ; Şireli et al., 2006 ), Spain (Perello et al., 2008 ) and Poland (Rajkowska‐Myśliwiec et al., 2021 ), the majority of them were from Nigeria (Amos‐Tautua et al., 2013 ; Anigboro et al., 2011 ; Aremu et al., 2014 ; Daniel et al., 2013 ; Ersoy et al., 2006 ; Ibanga et al., 2019 ) and other African countries such as Egypt (Abbas et al., 2021 ), Ghana (Kobia et al., 2016 ) and Burkina Faso (Bazié et al., 2021 ). Heavy metals contamination data (Table 5 ) showed that before 2015 (2006–2014) many studies from different countries especially Turkey and Nigeria were carried out on the occurrence of these environmental contaminants in smoked or grilled fish and meat.…”

“…Environmental pollution is the main way of food contamination with heavy metals (Costa et al, 2016 Several authors reported the presence of trace elements in smoked fish (Anigboro et al, 2011;Ibanga et al, 2019;Inobeme et al, 2018). Şireli et al (2006) reported the presence of lead (0.01-0.8 mg/kg) in vacuum packaged smoked fish marketed on the Ankara market in Turkey (Table 5).…”

Bacteria associated with smoked catfish sold at Bida Modern market, Northcentral Nigeria

“…and Proteus mirabilis were the bacteria isolates associated with smoked fish from Bida modern market Niger state. Similarly, the presence of this groups of bacteria's have also been reported in the bacteriological assessment of some fresh and smoked catfish in Nigeria [2,[10][11][12][13] . The present of most of this species of bacteria can be attributed to contamination of sampled fish by man through handling and processing [14] .…”

“…The bacterial colony counts result of catfish in Bida modern market shows a mean value of 1.84×10 6 cfu/g, this high population of bacterial colony could be due to poor or unhygienic conditions of the environment in which the fish samples were processed, packaged and preserved [11] , and also personal hygiene of the fish handlers [1,2,10] . Also, gross contamination of the fishes can be attributed to means or source of transport employed in transporting the fishes from their sources and processing to the market as they are exposed to dust and other environmental issues [12,13] . The result of the present study revealed a total of seven bacteria species consisting of four (4) gram-positive bacteria and three (3) gram-negative bacteria.…”