Smoked Fish Species Research Articles

Polycyclic Aromatic Hydrocarbon (PAH) Contents of Four Species of Smoked Fish from Different Sites in Senegal.

Polycyclic aromatic hydrocarbons (PAHs) are compounds resulting from any incomplete combustion process. These are pollutants that have proven toxicity due to their carcinogenic nature and can contaminate food during traditional smoking methods. Their highly toxic effect on human health requires monitoring of their levels in food products and the development of appropriate analytical methods for their determination. Thus, this study was conducted to assess the level of PAHs contamination of four (4) species of smoked fish (Arius heudelotii, Sardinella aurita, Ethmalosa fimbriata, and Sardinella maderensis) which were sampled in seventeen (17) localities in Senegal. The compounds targeted in this study were benzo(a)pyrene (B(a)P), benzo(a)anthracene (B(a)A), benzo(b)fluoranthene (B(b)F), and chrysene (Chr). The QuEChERS method was used for the extraction of PAHs, and their contents were quantified by gas chromatography (GC) coupled with mass spectroscopy (MS). The validation method was performed in accordance with the French standard NF V03-110 (2010). Satisfactory linearity (R2 > 0.999), LOD (0.05-0.09 μg/kg), LOQ (0.19-0.24 μg/kg), and precision (1.33-3.13%) of the four PAHs were obtained. The results of analysis in the 17 localities showed that all samples are contaminated by the four (4) PAHs with great variability of the contents between the different species and their origin. The B(a)P and ∑4PAHS contents in the samples ranged from 1.7 to 33 µg/kg and from 4.8 to 1082.3 µg/kg, respectively. Twelve (12) samples showed high levels of B(a)P, ranging from 2.2 to 33 µg/kg, thus exceeding the maximum authorized level (2 µg/kg). Fourteen (14) samples showed an overall ∑4PAHS content varying from 14.8 to 1082.3 µg/kg, which is above the maximum authorized limit (12 µg/kg). The principal component analysis showed that sardinella (Sardinella aurita and Sardinella maderensis) have very low levels of B(a)P, B(b)F, B(a)A, and Chr contents. However, high ∑4PAHS contents characterize smoked fish of the Kong species (Arius heudelotii), from Cap Skiring, Diogne, Boudody, and Diaobé, and of the Cobo species (Ethmalosa fimbriata) from Djiffer. Thus, based on the authorized limits for PAHs in smoked fish, it appears that smoked fish of the sardinella species are less carcinogenic for human consumption.

Microbiological status of smoked fish placed on the market in Poland

Fish and fishery products are considered to be one of the most nutrient-rich dietary products. The nutritional value of fish depends on its freshness. The greatest role in fish spoilage is played by microbial decomposition. Smoking is one of the methods of fish preservation based on the action of temperature and the penetration into the tissue of preservative substances produced by burning wood. Almost all microorganisms except some pathogenic bacteria are destroyed in the smoking process; nevertheless, fish can be a source of some pathogenic microorganisms, i.e. Listeria monocytogenes, Salmonella spp., Staphylococcus spp., which are present as the result of cross-contamination at the stage after smoking, i.e. marketing and storage (4, 5, 8). Improper and unhygienic handling practices with the ready-to-eat RTE product are also the cause of an increase of the total microbiological contamination, which can be expressed by microbiological contamination indicators, i.e. total viable count (TVC), psychrophilic bacteria count (PBC), coliform count (EBC), total yeast and mould count (TYMC) and total staphylococci count (TSC). In the performed study five smoked fish species (redfish, mackerel, codfish, sprat and herring) were tested at the marketing stage. A total number of 50 (N = 50) samples was tested according to ISO standards. The potential foodborne bacteria in the tested samples were identified using a MALDI-TOF spectrometer combined with MALDI-Biotyper 3.0 software. In the performed study, the highest microbiology contamination TVC on the level 3.63 ± 0.15 log10 cfu/g and PBC on the level 3.04 ± 0.24 log10 cfu/g has been found in redfish muscle compared to herring, codfish, sprat and mackerel muscle. A significantly lower amount of 1.26 ± 0.12 log10 cfu/g yeast and moulds of was found in the muscle tissue of herring, compared to the other tested fish. The highest staphylococcal contamination of muscle tissue of redfish on the level 2.56 ± 0.15 log10 cfu/g and mackerel on the level 2.13 ± 0.15 log10 cfu/g was found. MALDI-TOF identification of isolated bacteria not confirmed the presence of Salmonella spp., Listeria monocytogenes and pathogenic Staphylococci and confirmed the presence of E. coli in tested redfish.

English

Effect of smoking technologies on nutritional quality and concentration levels of polycyclic aromatic hydrocarbons (PAHs) in Mormyrus caschive and Oreochromis niloticus were determined to enable adoption and utilization of suitable facility that maintains good quality for sustainable supply of nutritious fish products in South Sudan. A total of 72 fresh M. caschive and O. niloticus were purchased, of which 24 were iced for reference and the other 48 were divided into two groups for pit and chorkor smoking. Experimental smoking of fish samples was conducted twice in a randomized design. Fish samples were analyzed for nutritional values using standard methods of the association of official analytical chemists and levels of PAHs using gas chromatography-mass spectrometry. Results revealed; the two smoking methods concentrated crude protein, fat and ash contents. However, fish smoked using chorkor had significantly higher nutritional values than fish smoked using pit kiln. About seven types of PAHs comprising of low and medium molecular weight were recorded from the two smoked fish species. Naphthalene and fluorene were the two dominant PAHs with fish smoked using pit kiln having significantly higher concentration levels of naphthalene (5.86±4.16 µg/kg) and fluorene (3.83±0.10 µg/kg) than fish smoked using chorkor oven. The study concluded that chorkor oven has better quality smoked fish than pit. Hence, its utilization and adoption for artisanal fisheries in South Sudan is recommended.   Key words: Nutritional values, food quality and safety, smoking techniques, polycyclic aromatic hydrocarbons (PAHs).

Fatty acid intake, biogenic amines and polycyclic aromatic hydrocarbons exposure through the consumption of nine species of smoked freshwater fish from Cambodia

This study presents the results from nine species of Cambodian smoked freshwater fish subjected to analysis of fatty acid, biogenic amines and polycyclic aromatic hydrocarbons (PAHs) with chromatographic techniques. The fatty acid profile of fish showed a high content of n-3 polyunsaturated fatty acids (PUFA) that can lead to a daily intake between 0.27 and 1.79 g for the sum of EPA and DHA. For PAHs, the exposure and risk assessments of consumers were carried out by calculating the estimated daily intake (EDI) which was compared to toxicological reference values. The margin of exposure (MOE) to PAHs through smoked fish consumption was calculated as the ratio between benchmark PAH levels and EDI. The exposure to histamine was calculated and compared with an acute reference dose (ARfD). Regarding PAHs, all tested samples were non-compliant with European legislation. Indeed, their level was exceeded up to 451 times for BaP and 308 times for the PAH4. MOE calculated for BaP were far below 10,000, revealing that Cambodian consumers are exposed to high levels of PAHs, possibly harmful for their health. For biogenic amines, histamine was detected in 4 samples, with concentrations leading to intakes below the ARfD of 50 mg/meal. In conclusion, smoked freshwater fish is on one hand a good source of PUFA for the Cambodian consumer, but on the other hand, could represent a major health concern because of PAHs contamination. The implementation of an improved smoking process, allowing to keep the PUFA content but to decrease the PAHs contamination, is urgently needed to insure the safety of Cambodian consumers. • Evaluation of some nutritional and safety aspects of smoked freshwater consumed in Cambodia was realized. • Samples from 9 freshwater smoked fish species were coming from 6 different Cambodian provinces. • Fatty acids, polycyclic aromatic hydrocarbons and biogenic amines were evaluated. • To assess the risk for the consumer, the margin of exposure was calculated.

Study of the Level of Polycyclic Aromatc Hydrocarbons (PAHs) in Some Locally Smoked Fish Species

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic pollutants which get into foods during processing. In spite of this, only a few studies have been carried out on Nigerian delicacies. This study was used to determine the level of PAHs in some smoked fish species namely: clarias gariepenus (catfish) , scomber scombrus (atlantic mackerel) and clupea harengus (herring fish). The fish species were smoked with a local open-fire fish smoking drum and PAHs were determined using the Gas Chromatography (GC) coupled with flame ionization detector (FID). The levels of PAHs were evaluated on the three species of fish. The total values of PAHs have shown that the smoked clarias gariepenus (catfish) , scomber scombrus (mackerel fish) and clupea harengus (herring fish) have 80.01μg/g, 69.94μg/g and 154.08μg/g respectively. Higher values were found in benzo(a)pyrene and lower values found in naphthalene. For benzo(a)pyrene, the values were 9.20μg/g, 2.90μg/g and 40.13 μg/g respectively. For naphthalene, the values were 1.13μg/g, 1.11μg/g and 1.72μg/g respectively. Benzo(a)pyrene, which is highly carcinogenic was found to have the highest concentration in clupea harengus (herring fish) of about 40.13μg/g which is above permissible level. As for the other PAHs, they were all detected in various quantities which resulted to the high level of the total PAHs in the samples. From the study, it was revealed that the open-fire fish smoking pose a health risk for human as it is being contaminated. It is therefore recommended that a low polycyclic aromatic hydrocarbons (PAHs) improved fish smoking kiln should be developed. Keywords: Polycyclic aromatic hydrocarbons, smoked fish, Gas chromatography, Benzo(a)pyrene, Carcinogenic DOI: 10.7176/CMR/13-3-03 Publication date: October 31 st 2021

Characterization of Smoking Activity and Perception of Smoked Fish by Households in the City of Douala (Cameroon)

Smoked fish contributes to the food security of populations through its richness in nutrients and its accessibility to low-income households. This study aimed to characterize the smoking activity and the perception of smoked fish by households in the city of Douala. For this purpose, two surveys were conducted from February to May 2021. The first exhaustive, involving 35 processors identified the actors, the methods used and the most smoked fish species in three smoking centers (Youpwé, Bonassama and Manoka). The second survey, cross-sectional, of 384 households in five subdivisions of the city of Douala focused on the socioeconomic characterization of households and their appreciation of smoked fish. SPHINX software (2018) was used for descriptive data analysis. This study revealed that 85.8% of processors are over 40 years old and 97.1% have a low level of education. The smoking time varies between 8 to 48 hours and the three smoking kilns (Metal-drum, Banda and Altona) commonly used have an impact on health. However, 98% of households, regardless of their social status, consume smoked fish at least once a week, and the most consumed fish species out of more than 17 identified are bunga (27.08%), cod (22.14%), mackerel (14.58%), sole (10.16%) and pike (5.73%). The results of this study provide valuable information and constitute a working basis for improving fish smoking sector in order to guarantee the quality of the smoked fish.

The benefit-risk analysis of omega-3 polyunsaturated fatty acids and heavy metals in seven smoked fish species from Siberia

In cold smoked species of genus Coregonus, identified by molecular genetic analysis, contents of fatty acids and heavy metals and arsenic were measured. The highest content of sum of long-chain polyunsaturated fatty acids of omega-3 family (LC-PUFA), namely eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids, 6.53 ± 0.78 mg g−1 wet weight, was characteristic of tugun Coregonus tugun. This is the first quantitative estimation (mg LC-PUFA per g of product) of the nutritive value of smoked fish. Thus, to obtain a daily personal doze of EPA + DHA of 1 g, recommended for prevention of cardiovascular diseases, one needs to consume 153 g of the smoked tugun. Metals contents did not exceed standards for fish meat except Pb in least cisco Coregonus sardinella. Accordingly, values of hazard quotients, which estimate benefit-risk ratio of fish intake, indicate that most of the smoked fish species are safe product for human nutrition, except least cisco regarding Pb content.

PRELIMINARY ASSESSMENT OF PROXIMATE COMPOSITION, MINERAL AND ENERGY CONTENTS IN LOCALLY SMOKED PELLONULA LEONENSIS AND SARDINELLA MADERENSIS FROM BADAGRY CREEK, LAGOS STATE, NIGERIA

Knowledge of food composition is crucial in the assessment of nutritional quality and potential contribution to recommended nutrient intakes. Fish plays a major role in ensuring food and nutritional security among the poor, vulnerable and rural fishing communities. However, there is paucity of information on the nutritional value of fish species exploited by the artisanal fisheries in Nigeria. The present study was carried out to evaluate (i) the nutritional value in two locally smoked clupeids (Sardinella maderensis and Pellonula leonensis); (ii) each species in relation to recommended nutrient intakes in pre-school children(< 5 years) and elderly (men and women >70 years) and (iii) linkages between nutrient access and intake. Fresh samples were collected from Badagry Creek, smoked using local smoking kiln and analyzed according to AOAC standard method. Data were collected in duplicates and analyzed using t-test. There were significant differences (p < 0.05) in the proximate composition except for crude fibre between the two fish species. The percentage cover of daily recommended intake of phosphorous and calcium from the two species were very low (1. 81-3.7%; 0.023% - 0.0912%) but low to moderate for zinc (2 % - 22.50%) in pre-school children and the elderly. Sequel to the results obtained in this study, the two smoked fish species showed good nutritive qualities for human health despite the low to moderate contents of calcium, zinc and phosphorus contents.

Polycyclic Aromatic Hydrocarbons in Smoked Ethmalosa fimbriata and Gymnarchus niloticus from Selected Fish Markets in the Niger Delta, Nigeria

Polycyclic aromatic hydrocarbon (PAH) concentrations in edible muscles of two smoked fish species (Ethmalosa fimbriata and Gymnarchus niloticus) collected from different fish markets in the Niger Delta in Nigeria were determined. The aim of the study was to ascertain the PAH composition and consequent potential human health risk through dietary ingestion of these smoked fish species. The Σ16 PAH concentrations varied from 237 to 965 µg kg−1. The compositional pattern of PAHs in the fish species showed the prevalence of 2–4 ring PAHs over 5–6 ring PAHs. The carcinogenic potency (BaPTEQ) values ranged from 5.4 to 122 µg kg−1 and 27 to 102 µg kg−1 for E. fimbriata and G. niloticus, respectively, while the mutagenic potency (BaPMEQ) values varied from 2.8 to 135 µg kg−1 and 20 to 83.2 µg kg−1 for E. fimbriata and G. niloticus, respectively. The estimated incremental lifetime cancer risk from the ingestion of these fish samples varied from 1.04 × 10−9 to 2.34 × 10−8 which suggested that there is no considerable cancer risk arising from the ingestion of these fish species.

Bacterial and Fungal Population Assessment in Smoked Fish during Storage Period

Microbial contamination of food is the main obstacle of ensuring food safety. For this, the objective of this article was to determine the changes of microbial load of three smoked fish species (Tenualosa ilisha, Oreochromis mossambicus, Pangasius hypophthalmus) in fresh and stored condition. To fulfill that objective, the freshly smoked fish samples were collected from the laboratory of Fisheries and Marine Science Department, Noakhali Science and Technology University of Bangladesh. Total Bacterial Counts (TBC), Total Coliform (TC), Fecal Coliform (FC) and the density of Vibrio spp. and yeasts and molds spp. in the fresh and stored smoked fish were determined by using serial dilution and spread plate technique. The microbial assessments of stored smoked fish species were performed in every seven days interval up to one month storage periods. At the first sampling day of smoked fish species, TBC, TC, FC, Vibrio spp. and yeasts and molds spp. were not found in fresh smoked fish species. But the microbial loads in smoked fish species were consequently increases with the increasing of storage time. The highest densities of microbial loads were found in experimental smoked fish species in the 3rd week of smoked fish storage in refrigerator. This may be occurred due to the contamination of raw product and final smoked product from the polluted culture environment or processing environment or due to the improper processing during smoking. The results of this research indicate that the new hygienic processing practices of smoked fish products can ensure the food safety for consumers by maintaining all the safety standards properly.

Existence of Periodic Properties of Solutions of Certain Autonomous Third Order Nonlinear Differential Equations

Introduction: Knowledge of food composition is crucial in the assessment of nutritional quality and potential contribution to recommended nutrient intakes. Fish plays a major role in ensuring food and nutritional security among the poor, vulnerable and rural fishing communities. However, in Nigeria, information on the nutrition content of some locally important fish species particularly after smoking or sun-drying is either lacking or missing. Aim: The present study was carried out to evaluate (i) the nutritional value of two locally smoked clupeids (Sardinella maderensis and Pellonula leonensis); (ii) in relation to recommended nutrient intakes in pre-school children (< 5 years) and elderly (men and women >70 years) and (iii) linkages between nutrient access and intake. Materials and Methods: Fresh samples were collected from Badagry Creek, smoked using local smoking kiln and analyzed according to AOAC standard method. Data were collected in duplicates and analyzed using t-test. Results: There were significant differences (P =.05) in the proximate composition except for crude fibre between the two fish species. The percentage cover of daily recommended intake of phosphorous and calcium from the two species were very low (1. 81-3.7%; 0.023% - 0.0912%) but low to moderate for zinc (2 % - 22.50%) in pre-school children and the elderly. Conclusion: Sequel to the results obtained in this study, the two smoked fish species showed good nutritive qualities for human health despite the low to moderate contents of calcium, zinc and phosphorus. Keywords: Badagry Creek, clupeids, nutritional quality, smoked fish, Nigeria, recommended nutrient intakes.

Human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in smoked fish species from markets in Southern Nigeria.

Polycyclic Aromatic Hydrocarbons (PAHs) levels in four commonly consumed smoked fish species from markets in Southern Nigeria were assessed to evaluate possible human health risks associated with consumption. Varying levels of PAH congeners were observed in the fish tissues with the highest total concentration of PAHs in Scomber scombrus. High concentrations of benzo(a)pyrene was observed in Clarias gariepinus and Ethmalosa fimbriata with values above the guideline value of 0.05 mg/kg. The Dietary Daily Intake (DDI) value for total PAHs (∑PAHs) was highest for S. scombrus while the DDI value for the total carcinogenic PAHs (∑CPAHs) was highest for E. fimbriata. Carcinogenic human health risk assessment using carcinogenic toxic equivalents (TEQ), indicated that consumption of E. fimbriata has a higher potential to cause carcinogenic risks. TEQ values for all the fish species were however, below the estimated screening value (SV) of 3.556 mg/kg, while the estimated cumulative excess cancer risk (ECR) for E. fimbriata and C. gariepinus and PAH4 index for all the assessed fish species exceeded threshold values indicating potential carcinogenic risk from consumption.

Concentrations and risks of polycyclic aromatic hydrocarbons in smoke-cured fish products in Nigeria

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in nine popular smoked fish species, (Clarias gariepinus, Parachana obscura, Heterotis niloticus, Pseudotolithus senegalensis, Gymnarchus niloticus, Ethmalosa fimbriata, Sardinella aurita, Scromber scrombus and Trachurus trachurus), in the Nigerian market by using gas chromatography-mass spectrometry after extraction by ultrasonication with hexane/dichloromethane. The mean concentrations of ∑16 PAHs in these species ranged from 52.4 μg kg−1 to 1230 μg kg−1. The estimated margins of exposure (MOE values) were less than 10,000 for C. gariepinus, G. niloticus and E. fimbriata indicating serious concern for the consumers’ health. The estimated excess cancer risk factors for these fish species investigated indicate that approximately 1 to 65 out of 106 equally exposed adults may suffer from cancer and cancer-related diseases during their lifetime through the ingestion of carcinogenic PAHs from smoked fish in their diet.

English

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants representing an important group of carcinogens that have been detected in smoked fish. This work investigated the effect of fish smoking methods on dietary exposure to PAHs and potential risks to human health. The smoking methods considered accounted for differences in smoked catfish/solefish content of 16 PAHs. The results revealed traditional method of smoking had 7 genotoxic PAHs. Traditionally smoked catfish/solefish were 18 - 24 times higher than those measured by modern method. Risk assessment conducted using benzo[a]pyrene carcinogenic and mutagenic toxicity equivalency factors (TEF and MEF, respectively) showed low risk (2.01 x 10-8 - 2.86 x 10-8 and 1.09 x 10-8 - 1.83 x 10-8, respectively for carcinogenicity and mutagenicity) associated with consuming smoked catfish/solefish and below the USEPA guideline (1.0 × 10−5) for potential cancer risk. Mean hazard indexes were below 1 (below an acceptable cumulative threshold) ranging from 1.43 x 10-6 - 9.96 x 10-8. A significantly high accumulation of PAHs was found in the smoked fish as compared to the non-smoked fish control samples. This study indicates that there is no adverse health effect of PAHs content on consumers of smoked fish species but levels of PAHs present in smoked catfish/solefish prepared using traditional methods may pose elevated cancer risks if consumed at high consumption rates over many years.    Key words: Smoked fish, polycyclic aromatic hydrocarbons, mutagenic, carcinogenic, human health, hazard index.

Effects of Traditional Smoking Methods on the Concentrations of Polynuclear Aromatic Hydrocarbons (PAHs) in Some Species of Smoked Fish Traded in Benue State, Nigeria

<p>The effects of three traditional smoking methods on the concentrations of polynuclear aromatic hydrocarbons (PAHs) in smoked fishes were studied. Samples of five different species of fish highly traded for immediate consumption were purchased from fishermen and processed using saw dust smoke, firewood smoke and charcoal smoke respectively. Some of the fresh fishes were also sun-dried and analyzed as control. The PAHs content were extracted with standard dichloromethane using solid-liquid extraction, and analyzed using Gas chromatography – Mass spectrophotometer (GC-MS) method. The results showed that fish samples processed with saw dust smoke recorded the highest concentrations of total PAHs, ranging from 815.75 µg/kg to 1550.28 µg/kg, followed by firewood smoked samples with total PAHs content varying between 738.14 µg/kg to 994.09 µg/kg while charcoal smoked samples recorded the least total PAHs levels of 135.02 µg/kg to 614.42 µg/kg. Benzo(a)pyrene concentrations of 5.68 µg/kg and 5.44 µg/kg respectively were detected in the samples of <em>Arius heude loti </em>and Mud minnow processed using saw dust smoke. The Benzo(a)pyrene levels exceeded the EC regulatory limit of 5 µg/kg. Because benzo(a)pyrene has been associated with intense carcinogenicity in humans, its levels recorded in the smoked <em>Arius heude loti </em>and Mud minnow may have implication for the quality and safety of these fish products. Therefore, it is imperative that regulatory bodies conduct awareness campaigns to educate both the smoked fish processors, traders and consumers on the need to discourage the use of saw dust in smoking fish and adopt safer and improved methods of smoking fishes.</p>

Smoked And frozen fish consumption and marketing channels in the Tamale Metropolis of Ghana

Fish marketing has become an important trade in Ghana due to the increasing appreciation of the health benefits from consuming fish. This paper examines fish marketing and consumption in the Tamale Metropolis of Ghana with specific reference to consumer preferences. It discusses the results of a survey research that compares the marketing and consumption of smoked and frozen fish. One hundred and fifty respondents comprising smoked and frozen fish sellers and consumers were randomly selected and interviewed. Twenty-two smoked fish species were identified, out of which 12 were freshwater species while 10 were marine species. Eighty-six per cent (86%) of consumers preferred smoked fish while 14% preferred frozen fish. Herrings, horse mackerel and salmon were the most preferred fish. Consumer preferences were based on taste, affordability, availability and wholesomeness in soup and stew. The fishmongers indicated that they obtained their marine fishes from Kumasi (42%), Techiman (30%), Sunyani (19%), Tema (5%) and Takoradi (4%) whiles freshwater fishes were obtained from Yeji/Makango (52%), Buipe/Yapei (33%), Nawuni/Botanga (9%) and Techiman (6%). The study showed that the marketing channel of frozen fish was simple while that of smoked fish was slightly more complex. Averagely, prices per kilogram of frozen or fresh (GH¢ 3.80) fishes were relatively cheaper compared to smoked (GH¢ 3.80) fish species. KEY WORDS : Marketing, Consumers, Freshwater, Marine, Frozen Fish, Smoked Fish

Levels of PAHs and Potentially Toxic Metals in Three Species of Fresh and Smoked Fish Consumed in Lagos, Nigeria.

Three samples of fish, Scomber japonica (titus), Sardinellaeba (sardine) and Merlucciuspolli (fresh stock fish) were collected from Ojo main market in Lagos. Two low molecular weight polycyclic aromatic hydrocarbons (naphthalene and anthracene) were determined using high performance liquid chromatography, (HPLC), after extraction with n-hexane by ultrasonication and clean up using SPE cartridges. Heavy metals were determined in the samples using atomic absorption spectrometer, (Perkin Elmer, Analyst 200) after digestion with aqua regia. The fat content was determined gravimetrically. The unsmoked samples had naphthalene range from 0.0788±0.0078 µg/g in Merlucciuspolli to 0.3845±0.0199 µg/g in Scomber japonica. Anthracene levels ranged from 0.4798± 0.0072 µg/g in unsmoked samples of Merlucciuspolli to 1.2254±0.0071 µg/g in Scomber japonica. The low fat containing specie (Merlucciuspolli) accumulated PAHs over the smoking periods, while a decrease was observed in the high fat containing species (Scomber japonica and Sardinellaeba). The highest concentration of Pb (8.65 µg/g), Cu (9.53 µg/g), Fe (201.80 µg/g) and Zn (122.15 µg/g) in the unsmoked fishes were found in unsmoked Scomber japonica while the highest concentration of Cr (13.68 µg/g) and Ni (5.88 µg/g) in the fishes were found in the unsmoked Merlucciuspolli. Cadmium was not detected in all the samples. The low fat containing specie showed increase in heavy metals over the smoking periods, while the high fat containing species also accumulated these heavy metals at 1 hour smoking period, but a decrease was noted over the 2 hours and 3 hours smoking periods. Smoking has effect on the level of these toxicants, as PAHs and heavy metals tend to accumulate on smoking. Smoking appeared to influence toxicants levels the fishes. Levels of the PAHs were higher than the regulatory permissible limits of the World Health Organization. Levels of the toxic metals were within the WHO set permissible limits except for Pb (in unsmoked Scomber japonica), Fe (in Sardinellaeba smoked for 1 and 2 hours, and in Merlucciuspolli smoked for 2 and 3 hours) and Cr (in all the samples). Keywords: Toxicants, smoked and unsmoked fish, ultrasonication, SPE, HPLC.

Suitability of Four Smoked Fish Species to Dermestes maculatue (De Geer) [Coleoptera: Dermestidae

The suitability of four smoked fish species. namely. the Trigger fish (Balistes capriscus Gmelin). Catfish (Synodontis sp.), African catfish (Clarias gariepinus Burchel), and Nile tilapia (Orcochromis niloticus Linnaeus), for hide beetle. Dermestes maculatus (De Geer). development was investigated in the laboratory over a 90-day period. Significant (P<0.05) weight losses were recorded in the two multiple-choice and one no-choice tests with the highest weight loss (78.50±7.15 %) occurring in Synodontis sp. and the lowest weight loss (46.7±2.92 %) occurring in O. niloticus. Interactions between fish species and test methods were significant (P<0.05). The number of D. maculatus which emerged when the pest had free movement from one fish jar to another jar was significantly (P<0.05) higher compared with the test where the pest was confined to ajar containing a single fish species. Significantly higher number of adults developed on Clarias in the no-choice test.

Changes in physicochemical and sensory characteristics of smoke-dried fish species stored at ambient temperature

This study assessed the comparative changes in the physical and chemical components of five different species of smoked freshwater fish: Bony tongue, Heterotis niloticus, African carp, Labeo coubie, Snake fish, Parachanna obscura, Nile Tilapia, Oreochromis niloticus and African mud catfish, Clarias gariepinus during storage. The fish were smoke-dried to average moisture content of 10.41 ± 0.02% and stored. Fish were packaged in black polythene bags and kept in perforated plastic containers. The fish were left in the plastic baskets for 56 days at ambient temperature (25-32oC). Samples of fish were assessed weekly for physical attributes such as colour, fragmentation, odour, taste and texture. Proximate composition was assessed using changes in moisture content, crude protein, lipid and ash content. Biochemical indexes carried out were: Total Volatile Nitrogen (TVN), pH, Peroxide Value (PV) and Free Fatty Acid (FFA) levels. There was a general decline in physical attributes i.e. colour, fragments or cracks, odour, taste and texture of fish during storage. Fluffy woolly mat of moulds were noticed on the Clarias gariepinus from the 5th week of storage. There was a significant (P <0.05) colour change in most species as from the 6th week. During this study, the moisture content increased weekly in the five smoked fish species from the initial average of 10.41±0.02%. This could be attributed to the difference in the moisture of the smoked fish relative to the surroundings. Oreochromis niloticus and Heterotis niloticus had the best taste value. Apart from Parachanna obscura , the other fatty species, C. gariepinus and L. coubie became less firm as the weeks progressed. There were significant changes (P <0.05) in most of the physical and chemical characteristics except odour from the 6th week (42 days) of storage. There were also significant differences (P <0.05) between the initial and final values of the proximate and chemical constituents of the different species of fish. The study showed that keeping quality of smoked fish under ambient conditions decreases with increase in length of storage. Keywords : Freshwater fish, hot smoking, storage

Effects of insect infestation on nutritional quality of some smoked fish species in Jos, Nigeria

An assessment of the effect of insect pest infestation on the nutritional quality of four smoked fish species, Heterotis niloticus, Clarias gariepinus, Oreochromis niloticus and Protopterus annectens purchased from markets in Jos metropolis, north central Nigeria was carried out. The length of time between smoking of all the fish and procurement was between 5 to 7 days. Two insect pests associated with dried fish products; Dermestes maculatus (Degeer) and Necrobia rufipes (Degeer) were identified on the procured fish specimens. The levels of crude protein, crude fat, ash and moisture contents of the four fish species were carried out using standard methods of proximate analysis. Proximate analyses were conducted immediately after procurement and after 8-week storage period of the fish samples. Results showed significant decrease (P < 0.05) in the levels of crude protein and crude fat with increasing levels of beetle infestation over an 8-weeks storage period. Clarias gariepinus was significantly more affected (P < 0.05) than the other fish species with values of crude protein reducing from 72.00 to 50.90% for initial and final proximate analysis, respectively. However, the moisture content of the fish samples increased slightly over the 8-week storage period.