Biogenic amines in fish and shellfish

Detection, Identification, and Inactivation of Histamine-forming Bacteria in Seafood: A Mini-review

Seafood is one of the essential sources of nutrients for the human diet. However, they can be subject to contamination and can cause foodborne illnesses, including scombroid fish poisoning caused by histamine. Many microorganisms can produce enzymes that eventually decompose endogenous histidine to histamine in postmortem fish muscles and tissues. One of these is histamine-forming bacteria (HFB), primarily found in the gills, gut, and skin of fishes. Previous studies linked a plethora of Gram-negative HFB including Morganella spp. and Photobacterium spp. to scombroid fish poisoning from many types of seafood, especially the Scombridae family. These bacteria possess the hdc gene to produce histidine decarboxylase enzyme. It was reported that Gram-negative HFB produced 6345 ppm in tuna and 1223 ppm in Spanish mackerel. Interestingly, Gram-positive HFB have been isolated in the seafood samples with lower histamine levels. It suggests that Gram-negative HFB are the major contributor to the accumulation of histamine in seafood. Several analytical methods are available to detect and identify HFB and their histamine metabolites from seafood substrates. Rapid test kits can be used in food production settings for early detection of histamine to avoid food intoxication. Furthermore, high hydrostatic pressure and irradiation treatment could prevent the proliferation of HFB and inactivate the existing histidine decarboxylase (HDC) activity. As demonstrated in different seafood model systems, the HDC activity was deactivated at a maximum high hydrostatic pressure level of 400 MPa. The complete inactivation of HFB was achieved by gamma irradiation at a dose of 4.0 kGy. Other postharvest treatments, like enzymatic degradation and electrolyzed oxidizing water, were studied as sustainable methods for bacterial growth prevention and enzyme inactivation. However, other HFB react differently to these treatment conditions, and further studies are recommended.

Au Nanoparticles (NPs) Decorated Co Doped ZnO Semiconductor (Co400-ZnO/Au) Nanocomposites for Novel SERS Substrates

Au nanoparticles were decorated on the surface of Co-doped ZnO with a certain ratio of Co²⁺/Co³⁺ to obtain a novel semiconductor-metal composite. The optimal substrate, designated as Co₄₀₀-ZnO/Au, is beneficial to the promotion of separation efficiency of electron and hole in a semiconductor excited under visible laser exposure, which the enhances localized surface plasmon resonance (LSPR) of the Au nanoparticles. As an interesting finding, during Co doping, quantum dots of ZnO are generated, which strengthen the strong semiconductor metal interaction (SSSMI) effect. Eventually, the synergistic effect effectively advances the surface enhancement Raman scattering (SERS) performance of Co₄₀₀-ZnO/Au composite. The enhancement mechanism is addressed in-depth by morphologic characterization, UV-visible, X-ray diffraction, photoluminescence, X-ray photoelectron spectroscopy, density functional theory, and finite difference time domain (FDTD) simulations. By using Co₄₀₀-ZnO/Au, SERS detection of Rhodamine 6G presents a limit of detection (LOD) of 1 × 10^-9 M. As a real application, the Co₄₀₀-ZnO/Au-based SERS method is utilized to inspect tyramine in beer and the detectable concentration of 1 × 10^-8 M is achieved. In this work, the doping strategy is expected to realize a quantum effect, triggering a SSSMI effect for developing promising SERS substrates in future.

Formation, Analytical Methods, Change Tendency, and Control Strategies of Biogenic Amines in Canned Aquatic Products: A Systematic Review

ABSTRACT

Biogenic amines (BAs) are organic compounds with low molecular weight and can be used as indicators of the quality and safety of canned aquatic products during processing and storage. However, excess of these amines can cause foodborne poisoning. Therefore, the determination, analysis, and prevention of BAs are of great importance. This article focuses on the sources, formation, and pretreatment methods, as well as analytical techniques, change tendency, and control techniques of BAs, with the aim of promoting more appropriate analysis of canned aquatic products to provide a reference for the food industries.

HIGHLIGHTS

Modelling biogenic amines in fish meat in Central Europe using censored distributions

The aim of the study is to model concentrations of selected biogenic amines in various fish species (Atlantic salmon, Atlantic cod, striped catfish) bought in retail stores in Central Europe. Since the data contains non-detectable values, statistical methods for left-censored values from the exponential and Weibull distributions are applied and used to evaluate and compare the amount of biogenic amines in fish samples. Moreover, a risk of exceeding certain limits of biogenic amine concentrations to protect human health is determined. There are relatively high concentrations of putrescine, cadaverine and histamine in almost all fish species. Moreover, there was a significant difference in mean concentrations (distributions of concentrations, respectively) of histamine, tyramine and spermidine among the species.

Biogenic Amine Contents and Microbial Characteristics of Cambodian Fermented Foods

Naturally fermented foods are an important part of the typical diet in Cambodia. However, the food safety status of these products has not been widely studied. The aim of this study was, therefore, to provide an overview of the quality of these foods in relation to microbiology and biogenic amines. Additionally, the obtained results were compared to the habits and practices of Cambodians in handling this type of food. A total of 57 fermented foods (42 fishery and 15 vegetable products) were collected from different retail markets in the capital of Cambodia. Pathogenic Salmonella spp., Listeria spp., and Listeria monocytogenes were not detected in 25 g samples. Generally, less than 102 cfu/g of Staphylococcus aureus, Escherichia coli, Pseudomonas spp., Enterobacteriaceae, and molds were present in the fermented foods. Bacillus cereus group members (<102 to 2.3 × 104 cfu/g), lactic acid bacteria (<102 to 1.1 × 107 cfu/g), halophilic and halotolerant bacteria (<102 to 8.9 × 106 cfu/g), sulfite-reducing Clostridium spp. (<102 to 3.5 × 106 cfu/g), and yeasts (<102 to 1.1 × 106 cfu/g) were detected in this study. Still, the presence of pathogenic and spoilage microorganisms in these fermented foods was within the acceptable ranges. Putrescine, cadaverine, tyramine, and histamine were detected in 100%, 89%, 81%, and 75% of the tested products, respectively. The concentrations of histamine (>500 ppm) and tyramine (>600 ppm) were higher than the recommended maximum levels in respectively four and one of 57 fermented foods, which represents a potential health risk. The results suggest that the production process, distribution, and domestic handling of fermented foods should be re-evaluated. Further research is needed for the establishment of applicable preservation techniques in Cambodia.

Histamina e rastreamento de pescado: revisão de literatura

A preocupação com a qualidade do pescado sempre foi um tema recorrente, visto que é um alimento de alto valor nutricional para toda população, porém com grande susceptibilidade à deterioração e formação de substâncias prejudiciais ao homem, caso não sejam obedecidas as condições de conservação. Um exemplo de substância formada é a histamina, uma diamina biogênica primária e heterocíclica, não volátil, termoestável, originada pela descarboxilação da L-histidina, quando as condições de manuseio e estocagem são inadequadas, favorecendo a multiplicação da microbiota natural do pescado. A histamina possui potencial alergênico, podendo causar um quadro de intoxicação no ser humano e, em casos graves, levar à morte. Para tal problema, um sistema de rastreabilidade poderia ser a solução. Seu objetivo é garantir ao consumidor um produto seguro e saudável por meio do controle de todas as fases da produção, industrialização, distribuição e comercialização, possibilitando uma perfeita correlação entre o produto final e a matéria-prima que lhe deu origem. Em diversos países existem atualmente sistemas de rastreabilidade controlando a cadeia de pescado. No Brasil, vários entraves podem ser apontados para a não obrigatoriedade da rastreabilidade em pescado. A divisão de regulamentação do setor entre diferentes órgãos, tais como Ministério da Pesca e Aquicultura (MPA), Ministério da Agricultura, Pecuária e Abastecimento (MAPA) e a Agência Nacional de Vigilância Sanitária (ANVISA), a falta de articulação entre esses órgãos fiscalizadores, a baixa capacitação de mão de obra e a desvalorização dos produtos da pesca, o que trazem a descapitalização da base da cadeia produtiva. De tal maneira, pode-se afirmar que há uma série de desafios para que ocorra a implantação de um sistema de rastreabilidade em território nacional. De acordo com o exposto, este estudo objetivou, através de uma revisão bibliográfica sistemática da literatura, informar a situação atual da escombrotoxicose e da rastreabilidade da histamina em pescado.

Development of molecular approach based on PCR assay for detection of histamine producing bacteria

Histamine fish poisoning becomes highly concern not only in public health but also economic aspect. Histamine is produced from histidine in fish muscles by bacterial decarboxylase enzyme. Several techniques have been developed to determine the level of histamine in fish and their products but the effective method for detecting histamine producing bacteria is still required. This study was attempted to detect histamine producing bacteria by newly developed PCR condition. Histamine producing bacteria were isolated from scombroid fish and determined the ability to produce histamine of isolated bacteria by biochemical and TLC assays. PCR method was developed to target the histidine decarboxylase gene (hdc). The result showed that fifteen histamine producing bacterial isolates and three standard strains produced an amplicon at the expected size of 571 bp after amplified by PCR using Hdc_2F/2R primers. Fifteen isolates of histamine producing bacteria were classified as M. morganii, E. aerogenes, and A. baumannii. The lowest detection levels of M. morganii and E. aerogenes were 10(2) and 10(5) Cfu/mL in culture media and 10(3) and 10(6) Cfu/mL in fish homogenates, respectively. The limit of detection by this method was clearly shown to be sensitive because the primers could detect the presence of M. morganii and E. aerogenes before the histamine level reached the regulation level at 50 ppm. Therefore, this PCR method exhibited the potential efficiency for detecting the hdc gene from histamine producing bacteria and could be used to prevent the proliferation of histamine producing bacteria in fish and fish products.

Histamine and gut mucosal immune regulation

Histamine is a biogenic amine with extensive effects on many cell types, mediated by the activation of its four receptors (H1R-H4R). Distinct effects are dependent on receptor subtypes and their differential expression. Within the gastrointestinal tract, histamine is present at relatively high concentrations, particularly during inflammatory responses. In this review, we discuss the immunoregulatory influence of histamine on a number of gastrointestinal disorders, including food allergy, scombroid food poisoning, histamine intolerance, irritable bowel syndrome, and inflammatory bowel disease. It is clear that the effects of histamine on mucosal immune homeostasis are dependent on expression and activity of the four currently known histamine receptors; however, the relative protective or pathogenic effects of histamine on inflammatory processes within the gut are still poorly defined and require further investigation.

Formation of biogenic amines in crucian carp (Carassius auratus) during storage in ice and at 4°C

The formation of eight biogenic amines (BAs), total volatile base nitrogen (TVB-N), aerobic plate counts (APC), and sensory evaluation in crucian carp (Carassius auratus) during storage in ice and at 4°C were investigated. The sum of contents of all eight biogenic amines (SBA) in crucian carp increased from 49.82 to 197.09 mg/kg on day 36 when stored in ice and from 49.82 to 219.35 mg/kg on day 24 when stored at 4°C. TVB-N content increased with storage time; good relationships between TVB-N content and SBA were observed during storage in ice and at 4°C (R(2) = 0.95 and 0.93, respectively). APC of all samples significantly (P < 0.05) increased with storage time in the first 12 days and toward the end of the storage period, there were only minor changes; good relationships between APC and SBA were observed during storage in ice and at 4°C (R(2) = 0.96 and 0.58, respectively). According to sensory evaluation results, the crucian carp became unacceptable on days 24 and 16 during storage in ice and at 4°C, respectively. Putrescine and tyramine contents could be good quality evaluation indices for crucian carp during storage.

Biogenic amines in raw and processed seafood

The presence of biogenic amines (BAs) in raw and processed seafood, associated with either time/temperature conditions or food technologies is discussed in the present paper from a safety and prevention point of view. In particular, storage temperature, handling practices, presence of microbial populations with decarboxylase activity and availability of free amino acids are considered the most important factors affecting the production of BAs in raw seafood. On the other hand, some food technological treatments such as salting, ripening, fermentation, or marination can increase the levels of BAs in processed seafood. The consumption of high amount of BAs, above all histamine, can result in food borne poisoning which is a worldwide problem. The European Regulation established as maximum limits for histamine, in fishery products from fish species associated with high histidine amounts, values ranging from 100 to 200 mg/kg, while for products which have undergone enzyme maturation treatment in brine, the aforementioned limits rise to 200 and 400 mg/kg. Preventive measures and emerging methods aiming at controlling the production of BAs are also reported for potential application in seafood industries.

Scombroid poisoning: a review

Scombroid poisoning, also called histamine fish poisoning, is an allergy-like form of food poisoning that continues to be a major problem in seafood safety. The exact role of histamine in scombroid poisoning is not straightforward. Deviations from the expected dose-response have led to the advancement of various possible mechanisms of toxicity, none of them proven. Histamine action levels are used in regulation until more is known about the mechanism of scombroid poisoning. Scombroid poisoning and histamine are correlated but complicated. Victims of scombroid poisoning respond well to antihistamines, and chemical analyses of fish implicated in scombroid poisoning generally reveal elevated levels of histamine. Scombroid poisoning is unique among the seafood toxins since it results from product mishandling rather than contamination from other trophic levels. Inadequate cooling following harvest promotes bacterial histamine production, and can result in outbreaks of scombroid poisoning. Fish with high levels of free histidine, the enzyme substrate converted to histamine by bacterial histidine decarboxylase, are those most often implicated in scombroid poisoning. Laboratory methods and screening methods for detecting histamine are available in abundance, but need to be compared and validated to harmonize testing. Successful field testing, including dockside or on-board testing needed to augment HACCP efforts will have to integrate rapid and simplified detection methods with simplified and rapid sampling and extraction. Otherwise, time-consuming sample preparation reduces the impact of gains in detection speed on the overall analysis time.

Effect of filtered wood smoke treatment on chemical and microbial changes in mahi mahi fillets

A study was performed to investigate the effect of filtered wood smoke processing on quality and safety of mahi mahi compared to no treatment. Skinless mahi mahi fillet portions were either treated with filtered smoke (FS) or left untreated for 24 h, followed by either (a) aerobic storage at 4 degrees C for 8 d or (b) freezing for 30 d (-25 degrees C) followed by thawing and aerobic storage at 4 degrees C for 8 d. Results show that treating mahi mahi fillets with FS increased (P < 0.05) a* values (redness) of the muscle and stabilized it during frozen storage. The redness did, however, decay (P < 0.05) rapidly on cold storage for both defrosted and fresh filtered-smoke-treated products, and reached initial (presmoking) redness levels in 2 d. The FS process overall significantly (P < 0.05) improved microbial stability of the product. Stability toward lipid oxidation was also significantly (P < 0.05) increased for the FS products compared to untreated products, particularly after defrosting. Sensory studies supported the microbial and lipid oxidation findings, showing that products treated with FS were better accepted and had increased (P < 0.05) shelf life over the untreated products. The shelf life was, however, compromised when microbial levels increased; that is, the process did not mask microbial spoilage; the spoilage did become evident in the sensory trials.