Determination of heavy metals in selected black sea fish species

Heavy metals can be accumulated by marine organisms thought a variety of pathways, including respiration, adsorption and ingestion. The levels of heavy metals are known to increase drastically in marine environment through mainly anthropogenic activities. Fish are good indicators for the long term monitoring of metal accumulation in the marine environment. The aim of this study was to determine the levels of Cd, As, Hg, Pb, Zn and Cu in edible part and gill of seven most consumed Bulgarian fish species collected from north-east coast of Black Sea. These fish species are sprat (Sprattus sprattus sulinus), Mediterranean horse mackerel (Trachurus mediterraneus ponticus), Black sea gobies (Neogobius melanostromus), shad (Alosa pontica), Atlantic bonito (Sarda sarda), bluefish (Pomatomus saltatrix) and grey mullet (Mugil cephalus). The fish samples were collected during 2010. The analytical determination of As, Cd, Pb, Zn and Cu were performed by using flame and graphite furnace atomic absorption spectrometry after microwave digestion procedure. The total mercury determination was determined using a direct mercury analyzer (DMA-80). The metal concentration of analyzed elements was highest in the gill for all fish species. The maximum metal concentration was measured for Cu (1.40 mg kg⁻¹ w.w), Zn (11 mg kg⁻¹ w.w) and Pb (0.08 mg kg⁻¹ w.w) in muscle tissues of shad and sprat. The edible part of horse mackerel has the maximum value for Hg (0.12 mg kg⁻¹ w.w) while Atlantic bonito predominantly accumulates As (1.10 mg kg⁻¹ w.w). The analytical results obtained from this study were compared within acceptable limits for human consumption set by various health institutions.     

Levels of polychlorinated dibenzo-p-dioxins,dibenzo-p-furans and polychlorinated biphenyls in farmed sea bass (Dicentrarchus labrax) and sea bream (Sparus aurata) from Turkey

Farmed European sea bass and Gilthead sea bream were obtained from four different fish farms in Turkey during 2008–2009, for determination of 17 2,3,7,8-Cl-substituted PCDDs and PCDFs, and coplanar and indicator PCBs.Concentrations of ∑PCDD/Fs and DL-PCBs, as TEQ, in fish samples, ranged from 0.14 to 0.70 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight and from 0.46 to 4.51 pg TEQ₍₁₉₉₈₎ g⁻¹ wet weight, respectively. The concentrations of total indicator PCBs in fish samples ranged from 3.1 ng g⁻¹ to 22.1 ng g⁻¹ wet weight. Concentrations of PCDD/Fs and DL-PCBs were below the EU regulation (EC No. 1881/2006) limits.     

PCDD,PCDF and PCB contamination in Atherina boyeri (Risso, 1810) from Turkey

The levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (DL-PCBs) and indicator polychlorinated biphenyls were measured in Atherina boyeri (Risso, 1810) samples collected from Hirfanl? Dam Lake, Turkey in 2008 and 2009.Concentrations of PCDDs–PCDFs were detected as 0.16 and 0.17 pg TEQ₍₁₉₉₈₎ g^?1 wet weight while contamination levels of DL-PCBs were found as 0.42 and 0.38 pg TEQ₍₁₉₉₈₎ g^?1 wet weight in fish samples. The concentrations of total indicator PCBs in fish samples were found as 1.5 ng g^?1 and 0.9 ng g^?1 wet weight. Concentrations of PCDDs–PCDFs and DL-PCBs were below the EU regulation limits.     

Polybrominated diphenyl ethers (PBDEs) and indicator polychlorinated biphenyls (PCBs) in various marine fish from Zhoushan fishery,China

Levels of polybrominated diphenyl ethers (PBDEs) and indicator polychlorinated biphenyls (indicator-PCBs) were measured in thirty-two commonly consumed marine fish species from Zhoushan Fishery, China. Factors effecting the accumulation of the compounds in sea fish were discussed, as well as the associated health risk via fish consumption. Levels and congener profiles of these contaminants varied by fish type. Due to the different accumulation influenced by fat content, feed habits and living zone in the sea area, levels of total nine PBDEs ranged from 0.0085 ng/g wet weight (Pagrosomus major) to 1.6819 ng/g wet weight (Bullet mackerel). The corresponding values for six indicator-PCBs ranged from 0.0124 ng/g wet weight (Navodon septentrionalis) to 3.8244 ng/g wet weight (Bullet mackerel). Total PBDEs and total indicator-PCBs intakes for Chinese population were estimated according to the contaminant level in each fish species and mean fish consumption in China, using an average body weight as 60 kg for the general population. The estimated intake of total PBDEs and total indicator-PCBs ranged from 0.007 ng/kg bw/day (Pagrosomus major) to 1.402 ng/kg bw/day (B. mackerel) and 0.010 ng/kg bw/day (N. septentrionalis) to 3.187 ng/kg bw/day (B. mackerel), respectively. The evaluated health risk associated with PBDEs intakes and indicator-PCBs intakes via consumption of all the fish species are relatively low for Chinese resident.     

Anisakis sp. and Hysterothylacium sp. larvae in anchovies (Engraulis encrasicolus) and chub mackerel (Scomber colias) in the Mediterranean Sea: Molecular identification and risk factors

Larval ascaridoids in fish destined to human consumption represent an important public health issue, besides to be an economical problem. Indeed, marine ascaridoids are the etiological agents of the fish-borne zoonosis anisakidosis. Due to an increase of new cases reported worldwide, a continuous monitoring of infection in fish is mandatory. The study was aimed to evaluate the risk of infection by larval ascaridoids in fishes from Mediterranean Sea. Two species of fishes among those representing a major potential threat for human health were selected. Epidemiological and molecular study was carried out. At Milan Fish Market, Italy, 179 anchovies (Engraulis encrasicolus) and 84 chub mackerels (Scomber colias) caught in different fishing areas in the Mediterranean Sea were sampled and inspected for the presence of larvae. For each fish, larvae were counted and morphologically identified. Predictors of infections were investigated through general linear models. A subsample of 100 larvae was molecular characterized with PCR–RFLP targeting the nuclear ribosomal internal transcribed spacer (ITS) region. Moreover, 26 Hysterothylacium spp. larvae were analyzed by sequencing of both nuclear ITS and mitochondrial ribosomal rrnS regions.Overall, 1080 anisakids larvae were collected from 103 anchovies (P = 57.5%) and 53 chub mackerels (P = 63.09%). Larvae were morphologically identified as Anisakis Type I larvae (P = 6.14% in anchovies and P = 55.95% in chub mackerels) and as Hysterothylacium spp. (P = 54.18% in anchovies and P = 13.09% in chub mackerels). Fishing area and fish weight resulted predictors of both Anisakis Type I land Hysterothylacium spp. infections in anchovies; in chub mackerels, only fishing areas resulted to be associated to both infections. Molecular analysis on ITS region identified Anisakis pegreffii, heterozygote genotype between A. pegreffii and A. simplex sensu stricto, and Hysterothylacium aduncum. Sequences analysis on Hysterothylacium specimens revealed a great homogeneity in rrnS marker, with eight variable nucleotides and an average evolutionary divergence over all sequence of 0.3%.     

Assessment of poly-aromatic hydrocarbons in the aquatic species along Suez Gulf,Egypt, and their excess cancer risk to human

This study reports the concentrations of 16 PAHs in 10 of Aquatic Species samples collected along the Gulf of Suez, Eygpt, between 2016 and 2018. Among 10 species of fish investigated, Argyrops Spinifer; Pomadasys Stridens; Euthynnus affinis; Scomber Japonicus; Peneus Japonicas, detected the maximum concentration of PAHs followed by Nemipterus Japonicus; Oreochromis Niloticus; Trachurus Indicus; Rhabdosargus haffara; Sauridaundo squamis. The lower-molecular-weight PAHs were detected at highest levels. Estimated intakes of PAHs by fish consumption for the general population were ranged between 4.482 and 317.148?ng/kg bodyweight/day. Argyrops Spinifer contributed to the highest intakes of PAHs. The toxic equivalents (TEQs) of PAHs were calculated using a TEQ proposed in literature, and the intake ranged from 27.067 to 8951.220?pg TEQ/kg bodyweight/d. The estimated excess cancer risk value (5.40?×?10^?5–3.91?×?10^?3) from fish consumption for the general population exceeded the guideline value (1.0?×?10^?6) for potential cancer risk.     

Trace element levels of mushroom species from East Black Sea region of Turkey

The levels of trace metals of mushroom samples collected from East Black Sea region of Turkey were determined by flame and graphite furnace atomic absorption spectrometry after microwave digestion method. The accuracy of the method was corrected by standard reference material (NIST SRM 1573a Tomato Leaves). The contents of investigated trace metals in mushroom samples were found to be in the range of 18.9–64.8 μg/g for copper, 53.5–130 μg/g for manganese, 44.7–198 μg/g for zinc, 187–985 μg/g for iron, 0.54–10.8 μg/g for selenium and 0.9–2.5 μg/g for cadmium. Mushrooms species in the highest levels of trace elements were found Entoloma sinuatum for Cu and Zn, Leucoagaricus leucothites for Mn, Amanita pantherina for Fe and Se, Agaricus arvensis for Cd.     

Occurrence and distribution of anisakid nematodes in Grey gurnard (Eutrigla gurnardus L.) from the North Sea

Grey gurnard (Eutrigla gurnardus L.) is an abundant and widely distributed demersal fish in the North Sea. It is currently considered a sustainable stock, thus permitting future increased utilisation as a food resource. In order to address both consumer safety and aesthetical product quality, the occurrence and distribution of anisakid nematode larvae in Grey gurnard from two localities in the North Sea were investigated. Two anisakid species were recorded, i.e. Hysterothylacium aduncum in the viscera, and Anisakis simplex in both the viscera and flesh of the fish. Virtually all gurnards were infected with nematode larvae. However, H. aduncum was significantly less abundant than A. simplex in the fish from both localities. Only for the gurnards from the northernmost sampling locality there was a significantly positive correlation between host body weight and total A. simplex abundance. No such correlation was found for H. aduncum in either locality. Separate analyses of the Anisakis infection data in gurnards of marketable size (≥250 g) and pooled for both localities, revealed 83% prevalence of A. simplex larvae in the fish flesh, ranging 1–16 in intensity. The relative larval distribution between the viscera and flesh was 89 and 11%, respectively. Moreover, a significantly positive correlation was found between A. simplex occurring in the viscera and the flesh of this particular host size group, i.e. the number of larvae in the flesh appeared to increase with increasing infection level in the viscera. In general, Grey gurnard from the North Sea can be considered as heavily infected with nematode larvae. Especially the comparatively high abundance of A. simplex larvae in the flesh is of concern regarding the possible intensified utilization of Grey gurnard as a food resource.     

A survey of histamine content in seafood sold in markets of nine countries

Histamine content was investigated in some fresh scombroid fish including tuna (Thunnus spp), mackerel (Scomber Japonicus) etc, and non-scombroid fish including mahi–mahi (Coryphaena hippurus), sardine (Sardina pilchardus), herring (Clupea harengus) etc, and fish products (sauce, dried fish) which came from Fiji, Germany, the Netherlands, Norway, Thailand, Cambodia, the Philippines, Japan and China. Histamine was detected in 35 of the 159 fish samples tested for a detection rate of about 21%. Fish samples exceeding 50 ppm histamine occurred in about 9% of the samples with 5 samples exceeding 500 ppm of which 2 were above 1000 ppm. Fish sold in markets in some countries may cause a histamine risk to consumers while other countries may have the necessary controls in place.     

Seasonal investigation of heavy metals in marine fishes captured from the Bay of Bengal and the implications for human health risk assessment

To investigate the seasonal contamination levels and to evaluate the potential human health risks, ten heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, and Zn) were measured in ten different marine fish species from the Bay of Bengal during four seasons. The metal concentrations varied significantly (p < 0.05) among the fish species with maximum and minimum accumulation of Zn (46.47 μg/g) and Cd (0.25 μg/g), respectively. The fishes captured during summer accumulated a higher amount of metals relative to other seasons, which was attributed to a higher influx of agricultural waste, sewage and sludge by heavy rainfall and floods. According to estimated daily intake (EDI), target hazard quotient (THQ), total target hazard quotient (TTHQ), and the permissible safety limits prescribed by various agencies, consumption of the examined fish species should be considered as safe for human health. However, the estimation of carcinogenic risk (CR > 10⁻⁵) due to exposure to arsenic indicated that consumers remain at risk of cancer.     

Effect of Anisakis simplex (sl) larvae on the spoilage rate and shelf-life of fish mince products under laboratory conditions

Wild caught marine fish are commonly infected with anisakid nematodes lodging in the intestinal linings or in the fish muscle. One of the most commonly found nematode parasites in marine fish is Anisakis simplex. During production of mince from the muscle of wild caught Anisakis-infected fish, the larvae would be disrupted during mince production. Any bacteria within or on the surface of such larvae are during the mincing process evenly distributed throughout the mince, and could thus possibly affect the spoilage rate of the final products. To explore if or how any bacteria associated with muscle-invading Anisakis larvae may affect the spoilage rate of fish mince, a controlled storage trial was conducted. Fillets of farmed Atlantic cod (Gadus morhua), exclusively fed on dried and heat-treated compound feed and hence expectably free from Anisakis larvae, were aseptically collected and homogenised. Fish mince aliquots were added different volumes of Anisakis homogenate based on larvae which were freshly sampled from the visceral cavity of NE Atlantic blue whiting (Micromesistius poutassou). The volumes of added parasite homogenate (parasite(+)-samples) reflected different infection intensities from 15 (low) to 50 (high) larvae per 100 g fish fillet, representing an actual Anisakis intensity range in the flesh of blue whiting. The samples were kept at 4 °C for 15 days and subjected to microbiological, sensory and chemical evaluation at 3 days intervals. Upon visual examination and plate count measurements (PC) on Iron Agar Lyngby (IAL), the samples without any parasite additives (no[parasite]) spoiled differently and more rapidly than any of the parasite(+)-samples. However, H₂S-producing bacteria were only recorded in the latter samples, which were also the only ones that showed increased levels of the spoilage indicator substance trimethylamine (TMA). Moreover, the parasite(+)-samples changed their sensory characteristics at a later stage compared to the no[parasite]-samples. Although some cultures of H₂S-producing bacteria were found on IAL, molecular identification by PCR-DGGE of the actual bacteria was not conclusive. Psychrobacter sp. which has no or only little spoilage activity, was identified in all samples until trial day 9, but was probably outgrown by the stronger spoilers Pseudomonas fluorescence/fragi and Photobacterium phosphoreum. Thus, and somewhat unexpected, our findings indicate that – under the present trial conditions – fish mince contaminated with bacteria which originate from Anisakis larvae, spoiled less rapidly than samples without any parasite-related bacteria present. Moreover, the shelf-life of fish mince was apparently not reduced by the presence of bacteria transferred to the mince by Anisakis larvae.     

Fish and mercury: Influence of fish fillet culinary practices on human risk

The influence of different culinary practices (boiling, frying, grilling) and seasoning (salt, lemon, combined) on the Hg levels (total and organic) found in three marine fish species (Scomber scombrus, Dicentrarchus labrax, Aphanopus carbo) was evaluated. Cooking affected the Hg levels in a species-dependent manner. With the exception of D. labrax, T-Hg decreased in grilling and frying, while O-Hg decreased in all culinary practices. For all species, some Hg was also found in the boiling water. Since O-Hg is the major portion of Hg in fish muscle and all culinary practices removed O-Hg, setting consumption thresholds in terms of T-Hg in raw tissue seems protective and adequate. S. scombrus and D. labrax emerge as healthier and safer choices, while moderate consumption of A. carbo is recommended. These findings reinforce the need to maintain FAO/WHO's recommendation that vulnerable groups should eat less than 100 g of predatory species per week.     

Composition of MSM from Brazilian catfish and technological properties of fish flour

The goal of this study was to analyze the physical and physicochemical composition and microbiological properties of mechanically separated meat (MSM) from Brazilian catfish (Brachyplatystoma vaillantii) and to prepare fish flour from this byproduct while assessing its technological properties, physicochemical and microscopic characteristics. After filleting, the residue was transported and stored at −22 °C and then subjected to mechanical meat separation so the fish flour could be prepared. The MSM analysis identified 17 fatty acids, of which the main ones were palmitic, oleic, stearic, palmitoleic, myristic, EPA, and DHA. The catfish MSM's amino acid profile had mainly glutamic and aspartic acids, arginine, lysine, and leucine. Salmonella spp or sulphite-reducing clostridia were not found in the MSM or the fish flour, while counts of coliforms at 45 °C (<3.0 MPN/g) and coagulase-positive staphylococcus (<1 × 101 CFU/g) were within the limits set by the Brazilian legislation. The fish residue had 78.36 g/100 g moisture, 9.52 g/100 g proteins, 10.80 g/100 g lipids and 18.41 mg TVB-N/100 g (within the Brazilian legislation standards). The best condition to prepare the fish flour was defined as 60 °C due to the best fit to the experimental data. The results suggest that using residues from Brazilian catfish filleting to make fish flour resulted in a product with high nutritional value able to increase value of several foodstuffs, besides contributing to the reduction of waste production in the region's fish industries.     

Antibacterial activity of plant essential oils and extracts: The role of thyme essential oil,nisin, and their combination to control Listeria monocytogenes inoculated in minced fish meat

Food poisoning caused by Listeria monocytogenes leads to a 30% rate of mortality among patients. The antibacterial activity of cinnamon, thyme, and rosemary essential oils (EOs) and shallot and turmeric extracts was tested against L. monocytogenes using agar well and disc diffusion techniques. Results showed that thyme EO had the highest antimicrobial activity, followed by cinnamon and rosemary EOs, respectively. The antilisterial activity of thyme EO at 0.4%, 0.8%, and 1.2% levels, nisin at 500 or 1000 IU/g level, and their combination against L. monocytogenes was examined in minced fish samples. The antilisterial properties of nisin were also investigated in cooked minced fish treatments. Nisin at 500 or 1000 IU/g in the minced fish meat demonstrated bacteriostatic activity against L. monocytogenes. The use of thyme EO at 0.8% and 1.2% reduced the L. monocytogenes viable count below 2 log cfu/g after 6 days. Furthermore, simultaneous use of thyme EO at 0.8% and 1.2%, and nisin at 500 or 1000 IU/g level, reduced the L. monocytogenes viable count below 2 log cfu/g after the second day of storage. The antilisterial activity of nisin in the cooked minced fish samples was slightly stronger than that of the raw group.     

Bacteriological quality and histamine-forming bacteria associated with fish meats and environments in HACCP and non-HACCP fish processing factories

Twenty fish meats and 21 environmental surface samples obtained from a Hazard Analysis Critical Control Points (HACCP) fish processing factory and two non-HACCP fish processing factories in Pingtung, southern Taiwan were tested to determine the hygienic quality and histamine-forming bacteria. The levels of aerobic plate count (APC), total volatile basic nitrogen and total coliform in fish samples obtained from the HACCP factory were significantly lower than those of fish samples obtained from the two non-HACCP factories. The average content of the eight biogenic amines in HACCP fish samples was less than 1.0 mg/100 g, while that in non-HACCP fish samples was less than 1.5 mg/100 g. In environmental surface samples, the average levels of ATP bioluminescence and APC (swabbing method) of HACCP processing factory were significantly (P < 0.05) lower than those of non-HACCP processing factories. Fifteen histamine-forming bacterial strains isolated from fish meats and environmental samples producing 2.3–561.5 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH), belonged to Enterobacteriaceae (thirteen strains) and Staphylococcus spp. (two strains).     

Assessment of trace elements in fishes of Japanese foods marketed in São Paulo (Brazil)

In recent years, there has been increasing fish consumption in Brazil, largely due to the popularity of Japanese cuisine. No study, however, has previously assessed the presence of inorganic contaminants in species used in the preparation of Japanese food. In this paper, we determined total arsenic, cadmium, chromium, total mercury, and lead contents in 82 fish samples of Tuna (Thunnus thynnus), Porgy (Pagrus pagrus), Snook (Centropomus sp.), and Salmon (Salmo salar) species marketed in São Paulo (Brazil). Samples were mineralized in HNO₃/H₂O₂ for As, Cd, Cr and Pb, and in HNO₃/H₂SO₄/V₂O₅ for Hg. Inorganic contaminants were determined after the validation of the methodology using Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES); and for Hg, an ICP-coupled hydride generator was used. Concentration ranges for elements analyzed in mg kg^?1 (wet base) were as follows: Total As (0.11–10.82); Cd (0.005–0.047); Cr (0.008–0.259); Pb (0.026–0.481); and total Hg (0.0077–0.9681). As and Cr levels exceeded the maximum limits allowed by the Brazilian law (1 and 0.1 mg kg^?1) in 51.2 and 7.3% of the total samples studied, respectively. The most contaminated species were porgy (As = 95% and Cr = 10%) and tuna (As 91% and Cr = 10%). An estimation of As, Cd, Pb, and Hg weekly intake was calculated considering a 60 kg adult person and a 350 g consumption of fish per week, with As and Hg elements presenting the highest contribution on diets reaching 222% of provisional tolerable weekly intake (PTWI) for As in porgy and 41% of PTWI for Hg in tuna.     

Occurrence and diversity of Bacillus cereus and moulds in spices and herbs

Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems for consumers and contribute to food spoilage and shelf-life reduction. The aims of the present work were (i) to determine the occurence and levels of B. cereus and moulds; (ii) to charactize the incidence and diversity of B. cereus emetic toxin (ces, CER), and diarrhoeal toxin-encoding genes (entFM, nheA, hblC, cytK) and toxigenic potential of Hbl toxin-producing B. cereus strains. Black ground pepper samples showed the most contamination with the highest concentration of B. cereus 2.49 log₁₀ CFU/g. Moreover, cumin contained the most prominent mould concentration level of 3.6 log₁₀ CFU/g. The most common moulds were Aspergillus and Penicillium spp. Compared to packaging type, all products acquired from the local market, except curry for B. cereus, exchibited high concentrations of B. cereus and moulds. Four genes were identified – 96% of B. cereus strains contained entFM, 94% nheA, 56% hblC, 42% cytK. None of the samples contained emetic toxin-encoding genes (ces, CER). Toxigenic potential of Hbl toxin was found in 72% of B. cereus strains. Different temperature, moisture levels and hygiene practices were observed at places of sale in local markets thus facilitating contamination and development of moulds. Moreover, the presence of B. cereus and its ability to produce toxins in spices and herbs, may suggest the need to establish microbiological criteria for mould and spore-forming bacteria in spices and herbs.     

Bacterial pathogens in fresh,smoked and salted Iranian fish

Salted and smoked fish are traditional products in Iran that are prepared by heavy salting (mixed salting) and heavy salting followed by cold smoking methods, respectively. Twenty eight Alosa kessleri (Caspian anadromous shad) from the Caspian Sea and 39 cultivated Hypophthalmichthys molitrix (silver carp) from two fish farms before and after a smoking process were examined using standard bacterial testing. Forty Liza aurata (Mullet dore) and 20 smoked H. molitrix purchased from a fish market (SMH-m) were also tested. Listeria monocytogenes were greater than 1 × 10² g⁻¹ in 2.6% of fresh (not smoked) H. molitrix (FH), 5.1% smoked H. molitrix, 20% SMH-m and 10% salted L. aurata (SAL). Vibrio parahaemolyticus was found in 21.4% fresh A. kessleri, 7.1% smoked A. kessleri, 5% SMH-m, 35% fresh L. aurata (FL) and 50% of SAL. For 7.5% of FL and 2.5% of SAL, V. parahaemolyticus were greater than 1 × 10² g⁻¹. Escherichia coli and Salmonella dublin were obtained in 30.8% and 2.6% of FH, respectively. No coliforms and Salmonella spp. were detected in salted fish and smoked fish. Staphylococcus aureus greater than 1 × 10⁵ cfu g⁻¹ were obtained in 55% SMH-m and 10% SAL. Consumption of these fish, either raw or undercooked may contribute to foodborne illness in Iran.     

Listeria monocytogenes in ready-to-eat vacuum and modified atmosphere packaged meat and fish products of Estonian origin at retail level

The prevalence, counts and genetic diversity of Listeria monocytogenes in ready-to-eat (RTE) vacuum and modified atmosphere packaged meat and fish products was studied in Estonia. Within two consecutive years 370 RTE food samples were collected at retail level from which 11% were found to be positive for L. monocytogenes. Contamination was higher among RTE fish products (17%) than in RTE meat products (6%). Generally, the counts of L. monocytogenes in positive products remained under ten colony forming units (CFU) per gram of product. Only 1.6% of the RTE meat and fish products contained L. monocytogenes in range of 10–100 CFU/g and 0.3% more than 100 CFU/g at the end of shelf-life. The food category containing highest L. monocytogenes prevalence was RTE lightly salted fish products with the prevalence of 32%. Only one (0.3%) RTE food sample exceeded the 100 CFU/g food safety criterion set out in the EU Regulation 2073/2005. Pulsed-field gel electrophoresis (PFGE) characterization of the isolates showed an overall similarity higher than 70%, and nine clusters based on 100% similarity were revealed. PFGE genotyping revealed that the few predominant pulsotypes were associated with particular food plants.     

Development of a fast screening method for the direct determination of chlorinated persistent organic pollutants in fish oil by high-resolution continuum source graphite furnace molecular absorption spectrometry

The occurrence of persistent organic pollutants (POPs), mainly organochlorine pesticides and polychlorinated biphenyls, was directly associated with several diseases and environmental endocrine disrupting. In the aquatic environment, POPs can accumulate in fish lipoid tissues due to their high hydrophobicity, and become this way one of the main sources of human exposure to POPs through the consumption of fish meat and oil as Omega-3 source. Chlorine might serve as a proxy for the presence of POPs, and a fast screening of chlorine in a complex matrix, such as fish oil, could provide substantial information about the contamination with POPs. Therefore, a method has been developed in this work for the determination of total chlorine in fish oil samples via molecular absorption of the strontium mono-chloride molecule in the gas phase using high-resolution continuum source graphite furnace molecular absorption spectrometry. The effect of zirconium as permanent chemical modifier in the pyrolysis and vaporization stages was optimized in order to avoid the need for any kind of sample preparation prior to the determination of total chlorine, using just a dilution with 1-propanol. The accuracy has been evaluated using micro-coulometric titration after sample combustion, and the values were statistically in agreement (95% confidence level) between both techniques. The method has been applied for the determination of total chlorine in five different fractions of a commercial pooled marine fish oil sample collected from the Pacific Ocean, where the majority of the fish is Peruvian anchovy (Engraulis ringens), two commercial oils from Brazil and three Omega-3 supplements acquired in Germany. The limit of detection of the procedure is 1.8 ng Cl absolute or 0.9 μg g⁻¹ Cl in the fish oil. The time required for a single determination is less than 5 min, and less than 15 min for a triplicate determination.