Tuna Samples Research Articles

Occurrence of trace metals in fish from South Italy: Assessment risk to consumer’s health

The concentrations of nine trace elements (Hg, Cd, Pb, V, Ni, Co, Cr, Cu and Zn) were determined in sixteen fish species collected in commercial centers of South Italy. Additionally, the assessment of risk indices (Hazard Quotient, Hazard Index, Incremental Lifetime Cancer Risk) through the consumption of various fish species were estimated in different age groups. The concentrations fell under the maximum permissible levels (MPLs) for human consumption recommended by European Union, with an only exception regarding Cd, which exceeded the tolerable value in Atlantic bluefin tuna samples. The estimated weekly intakes of metals, all below Provisional Tolerable Weekly Intakes (PTWIs), were in the following decreasing order: children > teenagers > adults > elders. The estimated hazard quotient (HQ) of Hg being above or close to 1 indicated a high probability of experiencing non-carcinogenic health risks, while the noncarcinogenic threats associated with exposure to other metals were insignificant (< 1) for all age groups. The cumulative cancer risk (ΣILCR) in children (1.86 × 10−3) and teenagers (1.10 × 10−3) exceed the cancer benchmark by a greater margin than adults (7.53 × 10-4) and elders (6.43 × 10-4). These results impose a systematic monitoring of fish, especially of large predatory fish, so to ensure the continuing safety of this food safeguarding human health.

Histamine test kit formation from Manganase (II), 5-fluorouracil and Alizarin red S complex compound

This researh aims to detect the presence of histamine by forming complex compounds of 5-fluorouracil, Mn (II) metal ions and alizarin red S reagents. This type of research is a laboratory experiment. This research was conducted at the Ikip Chemistry Laboratory in 2019. The results showed that the Test Kit that was made could be used to detect the presence of histamine determining the existence of histamine qualitatively viewable color formed based on complex compounds of Mn(II)-His-5FU-ARS seen from the shift in wavelength of maximum generated.. The making of the histamine test kit is made by varying the concentration of 10-100 ppm at 10 ppm  intervals under optimum conditions and can be used to make a color comparator solution. Then the method validity test is done by making a standard histamine curve that gives a regression equation y = 0.001x + 0.3364 with a correlation coefficient (r2) = 0.9972. Based on the validity test method, the accuracy value is in the range of 95.0-106% and the results of the test kit on tuna samples indicate that the histamine test kit made has a good accuracy value because the average recovery value is 96%.ÂÂ

In situ and real-time authentication of Thunnus species by iKnife rapid evaporative ionization mass spectrometry based lipidomics without sample pretreatment

Tuna adulteration and mislabeling are serious problem worldwide and have caused economic loss and consumer rights violation. In this study, an electrometric knife (iKnife) coupling rapid evaporative ionization mass spectrometry (REIMS) and a multivariate recognition model were developed and employed for in situ and real-time authentication of four tuna species without sample preparation. The results showed that the lipidomic profiles were successfully acquired and the differences in fatty acids and phospholipids were statistically analyzed to be significant (p < 0.05). The model displayed the superb classification accuracy (>93%) and validation (R2(Y) = 0.992, Q2 = 0.986), and the main contributors of m/z 817.64, m/z 809.68, etc. were screened out to be used as potential biomarkers. Based on this technique, the identity of blind tuna samples could be unambiguously authenticated with the results displayed on a monitor screen directly. This study provided a front-line rapid detection method to prove the authenticity of tuna species.

Effect of Glazing with Different Materials on the Quality of Tuna During Frozen Storage.

This study investigated and determined the changes in various qualities of tuna samples that were glazed with rosmarinic acid, a bamboo leaf antioxidant, and sodium lactate and stored at −18 °C for 180 days. The water-holding capacity, cooking loss, color, texture, protein content, and total volatile basic nitrogen (TVB-N) were monitored, to study the effect of tuna glazed with different materials on the quality every 30 days. Low-field nuclear magnetic resonance (LF-NMR) was used to measure the water distribution of tuna in this paper. The results showed that the quality of unglazed tuna decreased significantly after 180 days of frozen storage. During frozen storage, the hardness and a* values of RG (glazed with the rosmarinic acid group), SG (glazed with the sodium lactate group), and CG (glazed with the composite of rosmarinic acid, sodium lactate, and the antioxidant of bamboo leaf) tuna decreased slowly, while the malondialdehyde (MDA) value of AG (glazed with the antioxidant of bamboo leaf group) tuna increased slowly. After 180 days of frozen storage, CG tuna had the highest protein content and the lowest TVB-N value, which may have been due to the synergistic effect of glazing materials. The tuna with CG also had the best freshness and quality after frozen storage. Considering the results, a composite of rosemary (0.3%), sodium lactate (3.4%), and antioxidants of bamboo leaves (0.12%) is the best material for glazing tuna.

Occurrence of Histamine in Canned Fish Samples (Tuna, Sardine, Kilka, and Mackerel) from Markets in Tehran

Food poisoning is one of the most addressed health issues and has raised notable concerns. Histamine is the biogenic amine responsible for scombroid poisoning, which is due to the histidine decarboxylation by bacterial decarboxylases in various types of fish and fish products. The present investigation was conducted to measure the concentration of histamine in canned fish samples of tuna in oil (n = 18), tuna in oil with vegetables (n = 15), tuna in brine (n = 9), kilka in oil (n = 9), sardine in oil (n = 3), and mackerel in oil (n = 6) collected from markets in Tehran, Iran. Histamine concentrations were determined with a high-performance liquid chromatography device equipped with a UV detector. For method validation, the correlation coefficient (R2), recovery percentage, relative standard deviation for repeatability, limit of detection, and limit of quantification were 0.99, 82%, 1.3%, 1.5 mg/kg, and 5 mg/kg, respectively. Histamine was detected in 46.6% of the samples, and 18.3% of samples exceeded the histamine limit stipulated by the U.S. Food and Drug Administration (50 mg/kg). The overall mean histamine concentration was 17.36 ± 15.44 mg/kg, with a range of 0 to 88 mg/kg. A significant difference in histamine concentration was found between canned tuna in oil and canned tuna in brine (P < 0.05). However, no significant difference in histamine concentration was found among samples of canned tuna in brine, canned sardine in oil, canned kilka in oil, and canned mackerel in oil. Because of the high histamine concentrations detected in some brands of Iranian canned tuna, precise control programs, hazard analysis critical control point systems, and good hygiene practices should be implemented.

Quality of Longtail Tuna (Thunnus tonggol) in Different Storage Conditions

Low temperatures could inhibit bacteria producing histamine during fish handling process. Longtail tuna (Thunnus tonggol) is kept in ice starting from catching process until delivering to retail market to maintain quality of fish. However, long period of this storage causes growth of bacteria and deformation of histidine into histamine. This study was aimed to determine the effect of different storage conditions to the quality of longtail tuna through sensory and histamine test. Samples of longtail tuna were kept for 18 days in room temperature storage (28±2°C), cold temperature (0±3°C) and freezing temperature (-10±4°C). The quality of tuna was evaluated using Quality Index Method (QIM). The formation of histamine was analysed on day 0, 1, 2, 3, 4, 8, 14, 18 using spectrofluorometry method. Sensory acceptability limit at room temperature was one day, while cold storage reached 10 days with QIM score 11. Longtail tuna was spoiled on day 2 at room temperature with QIM score &gt;12 and concentration of histamin at 1713.88 mg/kg. The results of histamine in frozen and cold storage on the 18th day were 59.99 mg/kg and 77.98 mg/kg, these results exceeded the FDA limit (50 mg/kg) but still below the limit of FAO (100 mg/kg).The best storage condition is frozen storage, maintaining sensory acceptability and preventing histamine formation.

Detection of Kudoa hexapunctata and Kudoa neothunni from retail raw tuna in Japan using a novel duplex polymerase chain reaction

Kudoa hexapunctata was taxonomically separated from Kudoa neothunni, but their main host is tuna. K. hexapunctata has been identified as causative agent of foodborne diseases associated with the ingestion of raw Pacific bluefin tuna (PBT) in Japan, but K. neothunni has not. Therefore, it is clinically and epidemiologically important to detect and distinguish these two species. In the present study, we developed a novel duplex polymerase chain reaction (dPCR) targeting the 28S rRNA gene sequences of K. hexapunctata and K. neothunni. The dPCR amplified the desired genetic regions of each species, and the detection limit was 10 copies/reaction. A total of 36 retail tuna samples from different fishing ports were purchased and tested by dPCR. Thirty-one tested positive for K. hexapunctata and four tested positive for K. neothunni. Several retail PBT samples were examined in some of the fishing ports, and among these samples, the detection rates of K. hexapunctata was higher than 85%, and the rates were similar between wild and farmed PBT. The detection rates of K. hexapunctata in wild and farmed retail PBT were 75% and 71%, respectively, in May. However, the rates in June and July were 100% for both. K. hexapunctata and K. neothunni myxospores were not observed in the dPCR-positive samples, except in juvenile PBT, suggesting that the number of parasites was insufficient to cause foodborne disease. Thus, dPCR is a useful method for detecting and distinguishing K. hexapunctata and K. neothunni, and can be used in epidemiological studies of these parasites.

Accumulation of halogenated polycyclic aromatic hydrocarbons by different tuna species, determined by high-resolution gas chromatography Orbitrap mass spectrometry

Halogenated polycyclic aromatic hydrocarbon (HPAH) concentrations in tissues from three tuna species Thunnus albacares (yellowfin tuna), Katsuwonus pelamis (skipjack tuna), and Auxis thazard (frigate tuna) were determined by high-resolution gas chromatography Orbitrap mass spectrometry. The tuna samples were collected from the Indian Ocean. The instrument conditions gave high mass accuracy at 0.9 m/z isolation width of the mass filter and a mass error of <±1.0 ppm for many HPAHs. A total of 29 of the 30 targets chlorinated PAHs (ClPAHs) and 20 of the 21 targets brominated PAHs (BrPAHs) were detected in the tuna muscle samples. The mean total ClPAH, BrPAH and PAH concentrations for tuna were 127.2, 156.6 and 682.8 ng/g lipid weight, respectively. The mean total ClPAH and BrPAH concentrations (ng/g lipid weight) in the tuna were considerably lower than that of PAH concentrations. The mean total ClPAH, BrPAH and PAH concentrations in T. albacares respectively were 185.8, 249.2 and 784.1 ng/g lipid weight, irrespective of the body sizes. The mean total ClPAH, BrPAH and PAH concentrations in K. pelamis respectively were 45.1, 24.8 and 555.6 ng/g lipid weight. The mean total ClPAH, BrPAH and PAH concentrations in A. thazard respectively were 34.09, 4.73 and 433.24 ng/g lipid weight. The total ClPAH concentrations and body weights significantly positively correlated for T. albacares. The mean total ClPAH concentration in white muscles was significantly higher (p < 0.05) for large than for small T. albacares. This suggests ClPAHs could bioaccumulate in T. albacares, possibly because they are poorly metabolized. The chlorinated phenanthrene and pyrene concentrations indicated tuna accumulate these compounds increasingly effectively as the tuna grow. This was the first time large numbers of HPAHs were found in biological samples. HPAHs may adversely affect the health of humans consuming tuna.

Modeling Some Possible Handling Ways with Fish Raw Material in Home-Made Sushi Meal Preparation.

The aim of this work was to simulate selected ways of handling with raw fish after its purchase. The experiment was designed as three partial simulations: (a) trend in the biogenic amines formation in raw fish caused by breakage of cold chain during the transport after purchase, (b) the use of a handheld gastronomic unit as an alternative method of smoking fish with cold smoke in the household with regard to a possible increase in polycyclic aromatic hydrocarbon content, and (c) whether the cold smoked fish affects selected sensory parameters of nigiri sushi meal prepared by consumers. The material used in the research consisted of: yellowfin tuna (Thunnus albacares) sashimi fillets and the Atlantic salmon (Salmo salar) fillets with skin. The control (fresh/thawed tuna; without interrupting the cold chain) and experimental (fresh/thawed tuna; cold chain was interrupted by incubation at 35 °C/6 h) samples were stored at 2 ± 2 °C for 8 days and analyzed after 1st, 4th and 8th day of the cold storage. Histamine content was very low throughout the experiment, though one exception was found (thawed tuna without interrupting the cold chain: 272.05 ± 217.83 mg·kg−1/8th day). Tuna samples contained more PAH (4.22 µg·kg−1) than salmon samples (1.74 µg·kg−1). Alarming increases of benzo(a)anthracene (1.84 μg·k−1) and chrysene (1.10 μg·kg−1) contents in smoked tuna were detected.

Analytical possibilities of Putrescine and Cadaverine enzymatic colorimetric determination in tuna based on diamine oxidase: A critical study of the use of ABTS

The joint determination of putrescine (Put) and cadaverine (Cad) in the presence of other biogenic amines is studied using their enzymatic reaction with diamine oxidase (DAO). Three alternative methods are studied based on the intrinsic colorimetric properties of DAO or horseradish peroxidase (HRP), and the use of 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) colorimetric reagent, respectively. In this last case an in-depth study is carried out in order to explain and solve some drawbacks usually associated with the use of this reagent (especially interferences, interaction with enzymes and instability), and to propose new analytical methodologies which this reagent allows to achieve (transient signal and the use of the violet species). Finally, the method has been applied to Put + Cad determination in a tuna sample without interference of other biogenic amines. The result has been compared with that obtained using a method based on HPLC-MS, which has allowed the new methodology to be validated.

Biosensing the Histamine Producing Potential of Bacteria in Tuna.

Histamine poisoning is the most common cause of human foodborne illness due to the consumption of fish products. An enzyme-based amperometric biosensor was developed to be used as a screening tool to detect histamine and histamine-producing bacteria (HPB) in tuna. It was developed by immobilizing histidine decarboxylase and horseradish peroxidase on the surface of screen-printed electrodes through a cross-linking procedure employing glutaraldehyde and bovine serum albumin. The signal generated in presence of histamine at the surface of the electrode was measured by chronoamperometry at in presence of a soluble redox mediator. The sensitivity of the electrode was 1.31–1.59 μA/mM, with a linear range from 2 to 20 μg/ml and detection limit of 0.11 μg/ml. In this study fresh tuna filets purchased in supermarkets in different days (n = 8) were analyzed to detect HPB. Samples with different concentration of histamine were analyzed with culture-based counting methods, biosensor and HPLC and also a challenge test was made. Recovery of histamine from cultures and tuna samples was also assessed. The presence of Morganella psychrotolerans, Photobacterium phosphoreum, P. damselae and Hafnia alvei was detected using culture- and PCR-based methods. At the time of purchase these tuna samples had histamine concentrations from below the limit of detection (LOD) to 60 μg/g. HPLC and biosensor methods provided similar results in the range from zero to 432 μg/g (correlation coefficient, R2 = 0.990) and the recovery of histamine from cultures and tuna samples was very high (mean bias −12.69 to 1.63%, with root-mean-square error <12%). These results clearly show that fresh tuna is commonly contaminated with strong HPB. The histamine biosensor can be used by the Food Business Operators as a screening tool to detect their presence and to determine whether their process controls are adequate or not.

A 3D MRI-based Numerical Model Dedicated to Industrial Thawing of Large Tuna Fishes

ABSTRACTIndustrial thawing of raw tuna fishes for the canning industry is of great importance in the global economy. Due to the heat transfer limitations within large sample pieces, these processes need to be improved to reduce fluid and energy consumption. In this work, the water immersion thawing process of yellowfin tuna was studied from both experimental and numerical approaches. First, the heat transfer model is validated with precooked tuna samples undergoing forced-air convection thawing. Then, the water immersion thawing process of yellowfin was studied with temperature measurements performed under an industrial environment. The numerical model considers the real geometry of the yellowfin using magnetic resonance imaging (MRI) integrated into a 3D finite element model. Overall, good agreement was found between experimental and predicted temperatures by considering a uniform convective heat transfer coefficient. A simplified 2D model can accurately predict the thawing time, but a 3D model is needed to predict the spatiotemporal temperature distribution in the product. The results have also shown the strong influence of the ambient temperature on the thawing time. This original approach considering the real fish geometry could now be used with different sized-tuna and various thawing kinetics to reach optimal processing conditions while improving product quality.

Health Risk Assessment of Some Heavy Metals from Canned Tuna and Fish in Tijuana, Mexico

Background: A main route of heavy metal exposure is the consumption of contaminated food or water, resulting in negative health effects. Objectives: The objective of this study was to assess the health risk related to consumption of canned tuna and fresh fish by evaluating chromium (Cr), cadmium (Cd), mercury (Hg), and lead (Pb) concentrations. Methods: Forty-eight samples of tuna canned in water and 20 samples of different fish species sold in the city of Tijuana were used. Samples were digested by microwave-assisted digestion. Mercury was measured using the cold vapor atomic absorption spectrometry (CVAAS) method (United States Environmental Protection Agency (USEPA) method 7419b) and Pb, Cd, and Cr were measured using graphite furnace atomic absorption spectroscopy (GFAAS) (USEPA method 7010). Health risk assessment was conducted calculating the total hazard quotients (THQs) using the USEPA region III risk-based concentration table for adults. Results: The wet weight heavy metal concentrations in the canned tuna for Hg were 0.005 to 1.17 mg/kg, for Pb were 0.07 to 0.32 mg/kg, for Cd were from not detected (ND) to 0.007 mg/kg, and for Cr were 0.02 to 0.65 mg/kg. In the fresh fish samples, concentrations of Hg were 0.14 to 2.14 mg/kg, for Pb were 0.04 to 0.32 mg/kg, for Cd were 0.001 to 0.003 mg/kg, and for Cr were 0.07 to 0.38 mg/kg. The highest Hg concentrations were found in species of mako shark (Isurus oxyrinchus) and soupfin shark (Galeorhinus galeus). THQ values calculated were below one for all the samples. Conclusions: The results suggest that the consumption of canned tuna and fish in Tijuana does not represent a health risk for the general population in terms of exposure.

Identification of formalin and borax on tuna in Ngemplak market Tulungagung regency

Misuse of formalin and borax is still common, including processing and preserving fish. Therefore, this study aims to identify the presence of formalin and borax in tuna on the market Ngemplak, Tulungagung regency. The samples used in this study were fresh tuna in the Ngemplak market originating from the beaches of Prigi, Sine, Tambakrejo, Popoh and Sidem. The samples were tested qualitatively using the colorimetric method by Schryver reagent for formalin and curcumin paper for borax. The results obtained in this study, from the five tuna samples not detected contained formalin and borax which were marked by no change in color in the test. Tuna sold in the Ngemplak market Tulungagung regency negatively contains formalin and borax, making it safe for consumption. It is hoped that the relevant office will carry out routine checks on the misuse of food additives, especially preservatives circulating in the community and the public should always be careful in choosing safe food.

Quantitative TLC-SERS detection of histamine in seafood with support vector machine analysis

Scombroid fish poisoning caused by histamine intoxication is one of the most prevalent allergies associated with seafood consumption in the United States. Typical symptoms range from mild itching up to fatal cardiovascular collapse seen in anaphylaxis. In this paper, we demonstrate rapid, sensitive, and quantitative detection of histamine in both artificially spoiled tuna solution and real spoiled tuna samples using thin layer chromatography in tandem with surface-enhanced Raman scattering (TLC-SERS) sensing methods, enabled by machine learning analysis based on support vector regression (SVR) after feature extraction with principal component analysis (PCA). The TLC plates used herein, which were made from commercial food-grade diatomaceous earth, served simultaneously as the stationary phase to separate histamine from the blended tuna meat and as ultra-sensitive SERS substrates to enhance the detection limit. Using a simple drop cast method to dispense gold colloidal nanoparticles onto the diatomaceous earth plate, we were able to directly detect histamine concentration in artificially spoiled tuna solution down to 10 ppm. Based on the TLC-SERS spectral data of real tuna samples spoiled at room temperature for 0–48 h, we used the PCA-SVR quantitative model to achieve superior predictive performance exceling traditional partial least squares regression (PLSR) method. This work proves that diatomaceous earth based TLC-SERS technique combined with machine-learning analysis is a cost-effective, reliable, and accurate approach for on-site detection and quantification of seafood allergen to enhance food safety.

Differences in reaction of bigeye tuna (Thunnus obesus) and skipjack tuna (Katsuwonus pelamis) to intermittent light

The use of fish aggregating devices (FADs) in tuna purse seine fisheries are considered to affect the stock status of bigeye tuna (Thunnus obesus) in the Pacific, Indian and Atlantic Oceans as juvenile bigeye tunas tend to aggregate around the FADs and are caught along with skipjack tuna (Katsuwonus pelamis), the target species. International efforts to recover the stock status of bigeye tuna to sustainable level are under way. Regional fisheries management organizations have recommended measures to control fishing mortality of bigeye tuna by the FAD sets. In contrast, the skipjack tuna stock, the main target of the fishery, is considered healthy. As the two species coexist in a limited space around FADs, bigeye tuna is usually caught with skipjack tuna. To minimize the bigeye tuna bycatch at FADs while maintaining the catch of skipjack tuna, it is necessary to determine species-specific stimuli that can spatially separate the two species. We investigated the feasibility of using intermittent light as one such stimulus. The reactions of the two species to intermittent light of various frequencies (0.3, 0.5, 1.0, 1.7 and 5.0 Hz) and to combined intermittent (0.5, 1.0 and 5.0 Hz) and continuous light were tested. Bigeye and skipjack tuna samples were introduced alive into a 20-m-long cage and exposed to light stimulus. Behavior of fish in the cage was observed using two counter-oriented echo sounders. An underwater camera was used to monitor fish behavior and species identification. Skipjack tuna tended to move away from high-frequency intermittent light (5.0 and 1.7 Hz). In contrast, bigeye tuna showed less avoidance or even attraction to the same stimuli. Consequently, high-frequency intermittent light could be used to separate the two species.

Population Genetics and Phylogeography of Bigeye Tuna in Moluccas Seas, Indonesia

The bigeye tuna (Thunnus obesus) is a migratory fish which can be found in the Atlantic, Indian and Pacific oceans. This fish has a commercial value and has been exploited worldwide including in Indonesia. The exploitation might affect the genetic diversity and population structure. The fact that the population stock resource is abundant and following fishing activities are increasing, study on population genetic and phylogeography canbe used as information to determine the status of the fish population based on genetic data. The study was conducted to investigate population genetic, and phylogeography of bigeye tuna in the North Moluccas and South Mollucas Seas, Indonesia. A total of 60 tissue bigeye tuna samples were collected from two study sites. The samples were amplified using mitochondrial DNA control region. Within population genetic diversity was revealed of 0.985 and 1.00 in North Moluccas and in south Moluccas, respectively, while between populations was 0.989. The genetic distance within population of North Moluccas (0.029) and South Mollucas (0.24) was very low, and all population was 0.027. The genetic distance between population of North Mollucas and South Mollucas was 0.025, South Mollucas and all population was 0.023, and all population with Norht Mollucas was 0.027. The genetic distance of North Mollucas and Pacific Ocean was 0.029, South Mollucas and Pacific Ocean was 0.023, North Mollucas, South Mollucas and Indian Ocean was 0.32. The Fst value between populations (0.990) showed that the two populations were not genetically different. A similar result showed from the phylogenetic trees analysis which individual of bigeye tuna was randomly clustred between North Moluccas and South Mollucas population, indicating that they were genetically close and from the same population. The population bigeye tuna from the North Mollucas and the South Mollucas exhibits no apparent phylogeographic distribution.

Niveles de cadmio en atún fresco y enlatado para consumo humano en Ecuador

espanolActualmente, la bioacumulacion de cadmio (Cd) en peces esta aumentando y es un motivo de preocupacion debido a su toxicidad. El objetivo de esta investigacion fue determinar la concentracion de cadmio en 36 muestras de atun fresco y enlatado, provenientes de los mercados Caraguay, Puerto Pesquero Santa Rosa (PPSR) y atun enlatado de consumo nacional y de exportacion. Para cuantificar la concentracion de cadmio, las muestras de atun recolectadas fueron analizadas mediante el metodo de espectrofotometria de absorcion atomica. Los niveles de concentracion de cadmio de las muestras analizadas fueron comparados con la norma nacional NTE INEN 183 y 184, y con el Reglamento de la Union Europea No 488/2014, cuyo limite maximo permitido es de 0.10 ppm Cd. En atun enlatado de consumo nacional se encontraron concentraciones de 0.441±0.046 ppm Cd y en atun de exportacion 0.297±0.109 ppm Cd; sin embargo, las diferencias no fueron estadisticamente significativas (p>0.05). De igual forma, las concentraciones en atun fresco de la especie Katsuwonus pelamis fue de 0.385±0.174 ppm Cd, y de Thunnus albacares 0.295±0.187 ppm Cd en el mercado de Caraguay. Por el contrario, las concentraciones de Cd en atun proveniente del PPSR fueron mucho menores: 0.079±0.061 ppm Cd y 0.030±0.050 para Katsuwonus pelamis y Thunnus albacares, respectivamente. No hubo diferencias significativas entre el atun enlatado y fresco (p>0.05). El 66% de las muestras analizadas superaron los limites permisibles de Cd de las normas nacionales e internacionales, por lo que se recomienda mantener una vigilancia sanitaria permanente del atun en el Ecuador. EnglishCurrently, cadmium bioaccumulation in fish is increasing and is a concern due to toxicity. This research is intended to define the Cadmium concentration in 36 samples of fresh tuna and canning, respectively from the Caraguay Market in the city of Guayaquil, the fishing port Santa Rosa (PPSR), and canned tuna for national consumption and export. The cadmium concentration in the tissue of the collected tuna samples was analyzed by atomic absorption spectrophotometry. Levels of cadmium concentration in the analyzed samples were compared to the national regulation norm NTE INEN 183 and 184, and the European Union regulation norm No 488/2014. According to those norms the maximum permissible cadmium content in foodstuff might not exceed 0.10 ppm Cd. In canned tuna for national consumption we found concentrations of 0.441±0.046 ppm Cd and in the canned tuna for export the cadmium level varied around 0.297±0.109 ppm; differences were however not statistically significant (p>0.05). Similarly, the Cd concentrations in fresh tuna of the species Katsuwonus pelamis was 0.385±0.174 ppm and of the species Thunnus albacares 0.295±0.187 ppm in the market of Caraguay. In contrast, Cd concentrations in tuna from the PPSR were much lower: 0.079 ± 0.061 ppm Cd and 0.030 ± 0.050 for Katsuwonus pelamis and Thunnus albacares, respectively. 66% of the analyzed samples exceeded the permissible limits of Cd according national and international standards. It is recommended to maintain a permanent health surveillance of tuna in Ecuador.

Utilizing biosynthesized nano-enhanced laser-induced breakdown spectroscopy for proteins estimation in canned tuna

Proteins in canned tuna fish were assessed using laser-induced breakdown spectroscopy (LIBS) technique. Biosynthesized nanoparticles (BS-NPs) have been used to enhance the emission intensity of the spectral lines in LIBS spectra of tuna fish samples. Silver nanoparticles (Ag NPs) were biosynthesized in a simple and cheap way using potatoes (Solanum tuberosum) extract. Three cans from each of three different brands of high-, medium- and low-quality canned tuna fish were investigated. Six samples, pressed in small tablets, have been taken from each can. Half the number of samples was used for conventional LIBS measurements, while the other half was used for nano-enhanced LIBS. An enhancement of more than three times has been obtained in the spectral lines intensity of the biosynthesized nano-enhanced LIBS (BS-NELIBS) spectra. The intensities of CN and C2 molecular bands (at 388.34, and 516.52 nm respectively) in the obtained spectra are related to the proteins' content, and consequently to the quality of the different tuna fish brands. The conventionally estimated proteins' content in the three investigated brands of canned tuna validated the results obtained via BS-NELIBS. Quantitative estimation of the proteins in tuna samples was available using the correlation between the protein percentage measured conventionally and CN intensity in the relevant LIBS spectra. BS-NELIBS has been proven to be easy, fast and reliable analytical technique for the qualitative and quantitative estimation of the proteins in canned tuna fish. This method is feasibly applicable in the production monitoring of canned foods containing proteins.

Tuna labels matter in Europe: Mislabelling rates in different tuna products.

Tuna fisheries and processing represent economic activities of paramount importance around the world. Most of these products are traded for human consumption and in general are highly demanded commodities. However, not all tuna products achieve the same market price, some consumers are willing to pay a huge amount of money for certain species (i.e. Japanese market for Bluefin tuna) while other species are rather affordable (i.e. Skipjack tuna), therefore mislabelling has been observed frequently. We collected and analysed 545 tuna samples in six European countries, including fresh, frozen and canned products, and we have investigated whether or not these products were correctly labelled under European and national legislations. We found an overall mislabelling rate of 6.79%; in particular, 6.70% of the fresh and frozen tuna products and 7.84% of canned tuna were mislabelled, and only in the case of fresh and frozen tuna samples significant differences among countries were found. Mislabelling rates for Atlantic Bluefin tuna labelled products were very high, ranging from 50 up to 100%. In general, mislabelling was higher when specific names were included in the labels. The “tuna” umbrella term is a very popular one with consumers, but also one that remains vulnerable to ambiguity, hampering efforts towards market transparency and with potential negative consequences to the adequate management of tuna species stocks.