Development of chitosan based microencapsulated spray dried powder of tuna fish oil: oil load impact and oxidative stability / Desenvolvimento de pó microencapsulado por pulverização de óleo de atum à base de quitosana: impacto da carga de óleo e estabilidade oxidativa

Abstract The impact of fish oil concentration on the oxidative stability of microcapsules through the spray drying process using chitosan and maltodextrin as wall material was studied. Emulsions were prepared with different Tuna fish oil (TFO) content (TFO-10%, TFO20%, TF030% TF0-40%) while wall material concentration was kept constant. Microencapsulated powder resulting from emulsion prepared with high fish oil load have high moisture content, wettability, total oil and low encapsulation efficiency, hygroscopicity and bulk tapped density. Oxidative stability was evaluated periodically by placing microcapsules at room temperature. Microcapsules prepared with TFO-10% presented high oxidative stability in terms of peroxide value (2.94±0.04) and anisidine value (1.54±0.02) after 30 days of storage. It was concluded that optimal amounts of fish oil for microencapsulation are 10% and 20% using chitosan and maltodextrin that extended its shelf life during study period.

Resumo Foi estudado o impacto da concentração de óleo de peixe na estabilidade oxidativa de microcápsulas por meio do processo de secagem por atomização, utilizando quitosana e maltodextrina como material de parede. As emulsões foram preparadas com diferentes teores de óleo de atum (TFO) (TFO-10%, TFO20%, TF030% TF0-40%), enquanto a concentração de material de parede foi mantida constante. O pó microencapsulado resultante da emulsão preparada com alta carga de óleo de peixe tem alto teor de umidade, molhabilidade e óleo total e baixa eficiência de encapsulação, higroscopicidade e densidade extraída a granel. A estabilidade oxidativa foi avaliada periodicamente colocando microcápsulas à temperatura ambiente. As microcápsulas preparadas com TFO-10% apresentaram alta estabilidade oxidativa em termos de valor de peróxido (2,94 ± 0,04) e valor de anisidina (1,54 ± 0,02) após 30 dias de armazenamento. Concluiu-se que as quantidades ideais de óleo de peixe para microencapsulação são de 10% e 20% usando quitosana e maltodextrina que prolongaram sua vida útil durante o período de estudo.

Visual and rapid detection of escolar (Lepidocybium flavobrunneum) using loop mediated isothermal amplification in conjunction with a specific molecular beacon probe.

Species adulteration has become a main reason for the unexpected exposure to escolar, which is often related with the gastrointestinal disease called keriorrhea. Sensitive and accurate identification of escolar is required to protect consumers from commercial and health frauds. The present study established a visual and rapid method for escolar detection using LAMP (loop-mediated isothermal amplification) in conjunction with a MB (molecular beacon) probe. The visual MB-LAMP assay demonstrated high specificity and superb sensitivity (1 pg DNA) for escolar and low to 0.1 % (w/w) simulated adulteration could be detected within 25 min. Additionally, method validation on commercial products highlighted the umbrella term of white tuna for escolar on Chinese market. All these results indicated that the MB-LAMP method is a useful tool for rapid, sensitive and convenient detection of escolar and can also be used as a point-of-care molecular diagnostic technique since it does not require the expensive equipment.

Transcriptome characterization of gonadal sex differentiation in Pacific bluefin tuna, Thunnus orientalis (Temminck et Schlegel).

Tunas (genus Thunnus) are one of the most ecologically and commercially important fish worldwide. To establish a biological basis for reproduction in this globally essential species, we have recently studied crucial reproductive aspects of the Pacific bluefin tuna (T. orientalis; PBT), as a model of tuna species, based on our closed-cycle aquaculture technology. In this study, we clarified the global expression profile of the genes regulating gonadal sex differentiation in PBT, as this developmental process is vital to sexual reproduction. Based on the results of our comparative (RNA-sequencing) and temporal (qRT-PCR) transcriptome analyses using the updated genome dataset, we propose the molecular mechanisms of gonadal sex differentiation in PBT. In female gonads, foxl2 and cyp19a1a (coding aromatase) are expressed at the onset of sex differentiation. Active aromatase-mediated estrogen biosynthesis, which includes positive regulation of cyp19a1a expression by Foxl2, induces ovarian differentiation. By contrast, dmrt1 and gsdf are upregulated in differentiating male gonads lacking active estrogen synthesis. Dmrt1 and Gsdf would mainly promote testicular differentiation. Furthermore, androgen biosynthesis is upregulated in differentiating male gonad. Endogenous androgens may also be vital to testicular differentiation. This study provides the first comprehensive data clarifying the molecular basis for gonadal sex differentiation in tunas.

Why do cats love tuna so much?

Study identifies taste receptors that give our feline friends a craving for meat-and one fish in particular.

Near infrared sensors for the precise characterization of salt content in canned tuna fish.

Non-invasive technologies could help to guarantee quality standards of canned tuna fish. The aim of this study was to investigate the ability of bench-top (FT-NIR) and low-cost (LC-NIR) near infrared spectrometers to determine salt content and texture in canned tuna. Salt content distribution was also investigated using hyperspectral imaging (HSI) and computed tomography. Spectra were acquired on canned tuna and reference analysis performed. Partial least squares regression and discriminant analysis were used to develop salt content predictive and texture classification models. Salt content predictive errors were 0.10%, 0.22% and 0.22% for FT-NIR, LC-NIR and HSI, respectively. Salt content was not always homogeneously distributed in the can which was attributed to the salt content differences between internal and external parts of the tuna fish. Low-cost sensors could be a suitable solution to standardise the production and enable precise nutritional labelling, but more sophisticated algorithms are needed to identify textural defects.

Development of active packaging film based on poly (lactic acid) incorporated with Piper betel leaf ethanolic extract and its application in the shelf-life extension of tuna meat.

Active packaging films based on poly (lactic acid) (PLA) were developed by adding different concentrations (5 wt% and 10 wt%) of betel leaf (Piper betel) ethanolic extract (BLEE). The extract showed excellent antioxidant (80.2 %) and antimicrobial properties (18.05 and 16.05 mm against S. aureus and E. coli respectively). The films' structural, functional, and mechanical attributes were studied, along with their potential for extending the shelf life of tuna meat. The water solubility and water permeability were reduced with the incorporation of BLEE; while the tensile strength showed an inverse relationship with the concentration, 214.5 kg/cm2 (5 wt%), and to 307.6 kg/cm2 (10 wt%). The lipid oxidation in PLA-BLEE-packed tuna meat stored under refrigeration (7 days) showed a significant reduction, which could be attributed to the phenolic migration from the films. The new PLA-BLEE films with significant antibacterial and film attributes could be used in food packaging and to extend the shelf life of commodities that have been packaged.

Evaluation of a gold-nanoparticle-modified carbon-fiber microelectrode to quantify mercury in canned tuna sold in Ecuador.

Seafood consumption is the primary exposure route for trace metals like mercury. Accordingly, canned tuna meat has been focused on by researchers because of the potential bioaccumulation of high amounts of mercury. This study aimed to test a novel and reliable electroanalytical method employing a working electrode consisting of gold-nanoparticle-modified carbon microfibers to quantify total mercury in canned tuna samples. Determination was achieved via differential pulse anodic stripping voltammetry. The proposed method had a limit of detection of 3.9781 ± 0.0001 µg L-1 and a limit of quantification of 33.6634 ± 0.0001 µg L-1, with a sensitivity of 0.3275 nA µg L-1. The modified electrode was evaluated in samples taken from three canned tuna brands sold in the Sangolquí parish in Rumiñahui, Ecuador. These brands, coded A, B, and C, represent 47.92%, 27.08%, and 11.98% of all canned tuna sold in the Ecuadorian market, respectively. The resulting respective total mercury concentrations were 0.5999 ± 0.0001 mg kg-1; 0.9387 ± 0.0001 mg kg-1; and 0.3442 ± 0.0001 mg kg-1 for A, B, and C. Method accuracy was determined through the recovery percentages of ≥98%, which indicated acceptable accuracy for the final optimized method. Mean mercury concentrations for all samples did not represent a carcinogenic risk for consumers. However, the values obtained for potential no-carcinogenic risk and daily consumption rate suggest that consumers of tuna canned in water, particularly brand C, may be at risk.

Effects of company and season on blood fluke (Cardicola spp.) infection in ranched Southern Bluefin Tuna: preliminary evidence infection has a negative effect on fish growth.

Aporocotylid blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for Southern Bluefin Tuna (SBT), Thunnus maccoyii, ranched in Australia. Therapeutic application of praziquantel (PZQ) has reduced SBT mortalities, however PZQ is not a residual treatment therefore reinfection can occur after the single treatment application. This study documents the epidemiology of Cardicola spp. infection in ranched SBT post treatment over three ranching seasons (2018, 2019 and 2021). Infection prevalence (percentage of SBT affected) and intensity (parasite load) was determined by adult fluke counts from heart, egg counts from gill filaments and the use of specific quantitative polymerase chain reaction (qPCR) for detection of C. forsteri and C. orientalis ITS-2 DNA in SBT hearts and gills. SBT Condition Index decreased as intensity of Cardicola spp. DNA in SBT gills increased, suggesting blood fluke infection had a negative effect on SBT growth (Spearman's r = -0.2426, d.f. = 138, p = 0.0041). Prevalence and intensity of infection indicated PZQ remained highly effective at controlling Cardicola spp. infection in ranched SBT, 10 years after PZQ administration began in this industry. Company A had the highest prevalence and intensity of Cardicola spp. infection in 2018, and Company G had the highest in 2019. No consistent pattern was seen in 2021. Overall, intensity of infection did not increase as ranching duration increased post treatment. Results from this study improve our knowledge of the biology of blood flukes and helps the SBT industry to modify or design new blood fluke management strategies to reduce health risks and improve performance of SBT.

Cardiovascular complications are resolved by tuna protein hydrolysate supplementation in rats fed with a high-fat diet.

This study is aimed to investigate whether tuna protein hydrolysate (TPH) supplementation could alleviate cardiovascular complications induced by a high-fat diet (HFD) in rats. Rats were fed a HFD for 16 weeks and given TPH (100 mg/kg, 300 mg/kg, or 500 mg/kg) or metformin (100 mg/kg) (n = 8) for the last four weeks. TPH had the following effects: resolved their impaired glucose tolerance, hyperglycemia, dyslipidemia, obesity, and hypertension (p < 0.05); alleviated left ventricular dysfunction and hypertrophy (p < 0.05), and vascular dysfunction and hypertrophy (p < 0.05); adipocyte hypertrophy; increases in circulating leptin and tumor necrosis factor (TNF-α) were mitigated (p < 0.05); increased renin-angiotensin system (RAS), oxidative stress, and decreased nitric oxide metabolites were modulated (p < 0.05). TPH restored the expression of angiotensin II receptor type 1 (AT1R)/NADPH oxidase 2 (NOX2), endothelial nitric oxide synthase (eNOS), nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1), and peroxisome proliferator-activated receptor γ (PPARγ)/the nuclear factor kappa B (NF-κB) protein in cardiovascular tissue (p < 0.05). In metabolic syndrome (MS) rats, metformin and TPH had comparable effects. In conclusion, TPH alleviated cardiovascular complications related to MS. It suppressed RAS, oxidative stress, and inflammation that were associated with modulation of AT1R/NOX2, eNOS, Nrf2/HO-1, and PPARγ/NF-κB expression.

Evidence of isotopic maternal transmission influence on bluefin tuna (Thunnus thynnus) larval growth.

Pre-flexion stages of Atlantic bluefin tuna (Thunnus thynnus) larvae were collected in 2014 during the peak of spawning in the two main spawning areas: Gulf of Mexico (GOM) and Mediterranean Sea (MED). We examined daily growth, otolith biometry, and stable isotopes and found that the GOM grew at a faster rate, had larger otoliths, wider daily increments, and significantly lower values of δ15N when compared to the MED. In addition, an intra-population comparative analysis between slow- and fast-growing individuals (deficient vs. optimal growth groups, respectively) showed that optimal growth groups had significantly lower δ15N within each spawning area, implying a direct relationship between growth potential, development, and maternal transmission of isotopic signatures. A third pre-flexion larval group that was aquaculture-reared also exhibited the same pattern to the wild larval groups. In addition, for the first time, we estimated the maternal trophic niches using models developed with field-captured pre-flexion larvae. The estimated maternal trophic niches for the GOM were narrower than the MED, implying differences in the maternal trophodynamics from each nursery area. Overall, the inter-population (GOM vs. MED) and intra-population growth groups (deficient vs. optimal) grew faster and had narrower maternal niches. This study shows the advantages that larval SIA research can aid in the understanding of the trophodynamics of their breeders by examining the trophic relationship of a spawning stock jointly with the development of growth potential in offspring within the same breeding season.

New Insights into Phospholipid Profile Alteration of Bigeye Tuna (Thunnus obesus) during Daily Cooking Processes Using Rapid Evaporative Ionization Mass Spectrometry.

Bigeye tuna (BET, Thunnus obesus) is one of the most nutritious and luxurious cosmopolitan fish. The cooked BET products are capturing the interests of consumers by enhancing flavor and ensuring microbiological safety; however, the lipidomic fingerprints during daily cooking processes have not been investigated. In this work, lipid phenotypic data variation in BET during air-frying, roasting, and boiling was studied comprehensively using iKnife rapid evaporative ionization mass spectrometry (REIMS). The outstanding lipid ions mainly including fatty acids (FAs) and phospholipids (PLs) were identified structurally. It was demonstrated that the rates of heat transfer and lipid oxidation in air-fried BET were slower than those in roasted and boiled BET by elucidating the lipid oxidation and PL hydrolysis mechanism. Furthermore, multivariate REIMS data analysis (e.g., discriminant analysis, support vector machine, neutral network, and machine learning models) was used to characterize the lipid profile change in different cooked BET samples, among which FAC22:6, PL18:3/22:6, PL18:1/22:6, and others were the salient contributing features for determining the cooked BET samples. These results may provide a potential strategy for a healthy diet by controlling and improving functional food quality in daily cooking.

Industrial fisheries have reversed the carbon sequestration by tuna carcasses into emissions.

To limit climate warming to 2°C above preindustrial levels, most economic sectors will need a rapid transformation toward a net zero emission of CO2 . Tuna fisheries is a key food production sector that burns fossil fuel to operate but also reduces the deadfall of large-bodied fish so the capacity of this natural carbon pump to deep sea. Yet, the carbon balance of tuna populations, so the net difference between CO2 emission due to industrial exploitation and CO2 sequestration by fish deadfall after natural mortality, is still unknown. Here, by considering the dynamics of two main contrasting tuna species (Katsuwonus pelamis and Thunnus obesus) across the Pacific since the 1980s, we show that most tuna populations became CO2 sources instead of remaining natural sinks. Without considering the supply chain, the main factors associated with this shift are exploitation rate, transshipment intensity, fuel consumption, and climate change. Our study urges for a better global ocean stewardship, by curbing subsidies and limiting transshipment in remote international waters, to quickly rebuild most pelagic fish stocks above their target management reference points and reactivate a neglected carbon pump toward the deep sea as an additional Nature Climate Solution in our portfolio. Even if this potential carbon sequestration by surface unit may appear low compared to that of coastal ecosystems or tropical forests, the ocean covers a vast area and the sinking biomass of dead vertebrates can sequester carbon for around 1000 years in the deep sea. We also highlight the multiple co-benefits and trade-offs from engaging the industrial fisheries sector with carbon neutrality.

Spontaneous Osteogenic Differentiation of Human Mesenchymal Stem Cells by Tuna-Bone-Derived Hydroxyapatite Composites with Green Tea Polyphenol-Reduced Graphene Oxide.

In recent years, bone tissue engineering (BTE) has made significant progress in promoting the direct and functional connection between bone and graft, including osseointegration and osteoconduction, to facilitate the healing of damaged bone tissues. Herein, we introduce a new, environmentally friendly, and cost-effective method for synthesizing reduced graphene oxide (rGO) and hydroxyapatite (HAp). The method uses epigallocatechin-3-O-gallate (EGCG) as a reducing agent to synthesize rGO (E-rGO), and HAp powder is obtained from Atlantic bluefin tuna (Thunnus thynnus). The physicochemical analysis indicated that the E-rGO/HAp composites had exceptional properties for use as BTE scaffolds, as well as high purity. Moreover, we discovered that E-rGO/HAp composites facilitated not only the proliferation, but also early and late osteogenic differentiation of human mesenchymal stem cells (hMSCs). Our work suggests that E-rGO/HAp composites may play a significant role in promoting the spontaneous osteogenic differentiation of hMSCs, and we envision that E-rGO/HAp composites could serve as promising candidates for BTE scaffolds, stem-cell differentiation stimulators, and implantable device components because of their biocompatible and bioactive properties. Overall, we suggest a new approach for developing cost-effective and environmentally friendly E-rGO/HAp composite materials for BTE application.

Applications of Genomics, Metabolomics, Fourier Transform Infrared in the Evaluation of Spoilage Targets of Shewanella putrefaciens from Spoiled Bigeye Tuna.

Shewanella putrefaciens is a typical spoiler that is commonly found in seafood and has high spoilage potential. However, the spoilage mechanism against Shewanella putrefaciens at the gene and metabolism levels has not been well elucidated. This work determined the spoilage targets on Shewanella putrefaciens XY07 from spoiled bigeye tuna by genome sequencing, metabolomics, and Fourier transform infrared (FTIR) analysis. Shewanella putrefaciens XY07 contained some genes on spoilage regulating of cys genes, his genes, spe genes and rpoS gene involved in sulfur metabolism, histidine metabolism, arginine and proline degradation, and biofilm formation at the genome level, respectively. Some spoilage genes like speC, cysM, trxB genes were identified. In addition, ABC transporters, arginine and proline metabolism; beta-alanine metabolism; glycine, serine, and threonine metabolism; histidine metabolism; sulfur metabolism; and lipid metabolism were identified as important pathways related to aquatic food during spoilage, which indicated the functions of amino acid degradation in S. putrefaciens XY 07 by metabolomics analysis. The metabolites of l-ornithine, 5-aminopentanoate, and 4-aminobutyraldehyde could be further metabolized to spermidine and spermine, producing a spoilage odor, and were involved in arginine and proline metabolism serving as key spoilage regulating metabolisms. Therefore, Shewanella putrefaciens XY07 was applied to genomics, metabolomics analysis, and FTIR to provide comprehensive insight into the investigation of spoilage targets.

Running exercise with and without calcium supplementation from tuna bone reduced bone impairment caused by low calcium intake in young adult rats.

Inadequate calcium intake during childhood and adolescence is detrimental to bone metabolism. Here, we postulated that calcium supplement prepared from tuna bone with tuna head oil should benefit for skeletal development than CaCO3. Forty female 4-week-old rats were divided into calcium-replete diet (0.55% w/w, S1, n = 8) and low-calcium groups (0.15% w/w for 2 weeks; L; n = 32). Then L were subdivided into 4 groups (8/group), i.e., remained on L, L + tuna bone (S2), S2 + tuna head oil + 25(OH)D3 and S2 + 25(OH)D3. Bone specimens were collected at week 9. We found that 2 weeks on low calcium diet led to low bone mineral density (BMD), reduced mineral content, and impaired mechanical properties in young growing rats. Intestinal fractional calcium absorption also increased, presumably resulting from higher plasma 1,25(OH)2D3 (1.712 ± 0.158 in L vs. 1.214 ± 0.105 nM in S1, P < 0.05). Four-week calcium supplementation from tuna bone further increased calcium absorption efficacy, which later returned to the basal level by week 9. Calcium supplementation successfully restored BMD, bone strength and microstructure. However, 25(OH)D3 + tuna head oil + tuna bone showed no additive effect. Voluntary running also effectively prevented bone defects. In conclusion, both tuna bone calcium supplementation and exercise are effective interventions for mitigating calcium-deficient bone loss.

Assessment of microplastic contamination in an eastern Pacific tuna (Katsuwonus pelamis) and evaluation of its health risk implication through molecular docking and metabolomics studies.

This work investigated microplastic (MP) pollution in a commercially-important tuna species Katsuwonus pelamis (K. pelamis) from the Eastern Pacific and health implications. 125 MPs were extracted from gills, esophagus, stomachs, intestinal tracts, and muscle of K. pelamis. MPs in the esophagus was the highest, ∼7.6 times higher than that in the gill. Polyester and polyethylene terephthalate (PET) were dominant. Molecular docking implied that PET stabilized the complex via forming 4 new hydrogen bonds that interacted with Arg83, Gln246, Thr267, and Gly268, given that PET can enter glycerol kinase protein active pocket. Metabonomic results suggested that Glycerol 3-phosphate up expressed 1.66 more times that of control groups with no MPs in the muscle. This confirmed that MPs would lie in the glycerol kinase protein active pocket, which triggered menace to K. pelamis. The results provided insights into suggested the potential influence of MPs on the sustainability of fisheries and seafood safety.

Isotopic life-history signatures are retained in modern and ancient Atlantic bluefin tuna vertebrae.

Isotopic, tagging and diet studies of modern-day teleosts lacked the ability to contextualise life-history and trophic dynamics with a historical perspective, when exploitation rates were lower and climatic conditions differed. Isotopic analysis of vertebrae, the most plentiful hard-part in archaeological and museum collections, can potentially fill this data-gap. Chemical signatures of habitat and diet use during growth are retained by vertebrae during bone formation. Nonetheless, to fulfil their potential to reveal life-history and trophic dynamics, we need a better understanding of the time frame recorded by vertebrae, currently lacking due to a poor understanding of fish bone remodelling. To address this issue, the authors serially-sectioned four vertebral centra of the highly migratory Atlantic bluefin tuna (Thunnus thynnus; BFT) captured off Sardinia (Italy) and analysed their isotopic composition. They show how carbon (δ13 C), nitrogen (δ15 N) and sulphur (δ34 S) isotope values can vary significantly across BFT vertebrae growth-axes, revealing patterning in dietary life histories. Further, they find that similar patterns are revealed through incremental isotopic analysis of inner and outer vertebrae centra samples from 13 archaeological BFT vertebrae dating between the 9th and13th centuries CE. The results indicate that multi-year foraging signatures are retained in vertebrae and allow for the study of life histories in both modern and paleo-environments. These novel methods can be extended across teleost taxa owing to their potential to inform management and conservation on how teleost trophic dynamics change over time and what their long-term environmental, ecological and anthropological drivers are.

Inferring the ecology of north-Pacific albacore tuna from catch-and-effort data.

Catch-and-effort data are among the primary sources of information for assessing the status of terrestrial wildlife and fish. In fishery science, elaborate stock-assessment models are fitted to such data in order to estimate fish-population sizes and guide management decisions. Given the importance of catch-and-effort data, we scoured a comprehensive dataset pertaining to albacore tuna (Thunnus alalunga) in the north Pacific Ocean for novel ecological information content about this commercially valuable species. Specifically, we used unsupervised learning based on finite mixture modelling to reveal that the north Pacific albacore-tuna stock can be divided into four pseudo-cohorts. We discovered that smaller body mass pseudo-cohorts inhabit relatively high-subtropical to temperate-latitudes, with hotspots off the coast of Japan. Larger body mass pseudo-cohorts inhabit lower-tropical to subtropical-latitudes, with hotspots in the western and central north Pacific. These results offer evidence that albacore tuna prefer different habitats depending on their body mass, and point to long-term migratory routes for the species that the current tagging technology is unlikely to capture in full. We discuss the implications of the results for data-driven modelling of albacore tuna in the north Pacific, as well as the management of the north Pacific albacore-tuna fishery.

DNA metabarcoding to assess prey overlap between tuna and seabirds in the Eastern tropical Atlantic: Implications for an ecosystem-based management.

Overfishing has been drastically changing food webs in marine ecosystems, and it is pivotal to quantify these changes at the ecosystem level. This is especially important for ecosystems with a high diversity of top predators such as the Eastern Atlantic marine region. In this work we used high-throughput sequencing methods to describe the diet of the two most abundant tuna species, the Skipjack tuna (Katsuwonus pelamis) and the Yellowfin tuna (Thunnus albacares), highly targeted by fisheries off west Africa. We also explored prey diversity overlap between these tuna species and the seabird species breeding in Cabo Verde that are most likely to share prey preferences and suffer from bycatch, the Brown booby (Sula leucogaster) and Cape Verde shearwater (Calonectris edwardsii). Overall, the diet of both tuna species was more diverse than that of seabirds. Skipjack tuna diet was dominated by prey from lower trophic levels, such as krill, anchovies, and siphonophores, while the Yellowfin tuna diet was mainly based on epipelagic fish such as flying and halfbeak fishes. Some of the most abundant prey families detected in the Yellowfin tuna diet were shared with both seabird species, resulting in a high prey diversity overlap between this tuna species and seabirds These results have implications for the management of tuna fisheries in the Eastern Tropical Atlantic, because a large decrease of both tuna species might have cascading effects on both primary and secondary consumer levels, and the decrease of these underwater predators may have implications on the viability of tropical seabird populations.

Rapid, convenient, and ultrasensitive point-of-care sensing of histamine from fish: A Portable chromatographic platform based on derivatization reaction.

Food poisoning caused by histamine ingestion is one of the prevalent allergies associated with fish consumption in the world. Reliable detection of histamine from fish by a portable platform was of urgent importance to food safety. A portable technology for on-site monitoring of histamine in tuna was established through combined azo-derivatized thin-layer chromatography (TLC) with surface-enhanced Raman scattering (SERS) spectroscopy. The real tuna meat sample was directly applied onto the portable sensor for the separation of histamine and azo-derivatizing of histamine was reacted on the TLC plate. The colorless histamine was visualized by azo-derivatization after spraying Pauly reagent onto the diatomite TLC plate. The molecule information and concentration of the histamine was measured and calculated by SERS spectra. Diatomite TLC plate was capable of separating histamine with 1.32 × 10-7 M of Au colloid for the SERS enhancement. Accordingly, the limit of detection of histamine from mixture sample could achieve 2.8 × 10-4 ppm. These results indicated that the portable azo-derivatized TLC-SERS sensor not only visualizes the histamine but also improves the intensity of the Raman spectra. The azo-derivatized TLC-SERS sensor could be applied for rapid, convenient, and ultrasensitive point-of-care sensing of histamine in fish.