Raw Fish Products Research Articles

Assessing Listeria monocytogenes Growth in Artificially Inoculated Sea-Farmed Product—Raw Sea Bass (Dicentrarchus labrax) Fillet, Produced in Greece

Listeria monocytogenes (Lm) is responsible for listeriosis, a serious foodborne disease, with high hospitalization and mortality rates worldwide. The main cause of listeriosis in humans is the consumption of ready-to-eat (RTE) foods; Commission Regulation (EC) No 2073/2005 establishes microbiological criteria for Lm in RTE foods. Raw fish products are widely consumed, e.g., in sushi and various seafood recipes (e.g., carpaccio, sashimi, maki, nigiri, tartare, etc.), but are not subjected to RTE food safety criteria. The aim of our study was to assess the growth potential of Lm in raw sea bass fillets obtained from a leading aquaculture company in Greece. In order to assess the growth of Lm in raw sea bass fillets, we applied the “challenge test”, a scientific experiment designed to assess the growth of Lm within a specific food product under controlled conditions. According to our results, and taking into consideration the health risk for the listeriosis-vulnerable population, raw fish products utilized in the preparation of RTE foods, including sushi and an array of seafood dishes, should be incorporated in the Category of Safety Criteria of Regulation (EC) No 2073/2005 “Ready-to-eat food able to support the growth of Listeria monocytogenes”.

SOSIALISASI PENGEMASAN PRODUK, LABEL PRODUK DAN PEMBUATAN LAPORAN KEUANGAN SEDERHANA BAGI PELAKU UMKM DI DESA ADAT SANUR

Desa Adat Sanur has the potential for natural resources in the form of abundant fish, but the utilization of these natural resources to increase selling value is still not optimal because the fish is sold raw without any processing. In addition, the potential of Desa Adat Sanur is also a strategic tourism object, with this potential certainly having an impact on Micro, Small and Medium Enterprises (MSMEs) around Desa Adat Sanur. However, there are still many business actors who still combine their business money with their personal money and have not kept financial records so that business profits are also not recorded. Based on these problems, socialization of Micro, Small and Medium Enterprises related to increasing selling value and financial recording is important even though it is simple. This village project activity has solutions related to the problems previously described. The method used in this village project is in the form of socialization and mentoring regarding fish processing into finished products in the form of crackers, product packaging, product labels and making simple financial reports for Micro, Small and Medium Enterprises (MSMEs). The results of this village project can provide an understanding of the importance of recording good financial statements and provide an explanation of how to increase the selling value of fish through the processing of raw fish products into finished products in the form of fish crackers.

Ferrous sulfate efficiently kills Vibrio parahaemolyticus and protects salmon sashimi from its contamination

The primary seafood-borne pathogen Vibrio parahaemolyticus seriously threats the health of consumers preferring raw-fish products, becoming a global concern in food safety. In the present study, we found ferrous sulfate (FeSO4), a nutritional iron supplement, could efficiently induce the death of V. parahaemolyticus. Further, the bactericidal mechanisms of FeSO4 were explored. With a fluorescent probe of Fe2+, a significant influx of Fe2+ was determined in V. parahaemolyticus exposed to FeSO4, and the addition of an intracellular Fe2+ chelator was able to block the cell death. This suggested that cell death in V. parahaemolyticus induced by FeSO4 was dependent on the influx of Fe2+. It was intriguing that we did not observe the eruption of reactive oxygen species (ROS) and lipid hydroperoxides by Fe2+, but the application of liproxstatin-1 (a ferroptosis inhibitor) significantly modified the occurrence of cell death in V. parahaemolyticus. These results suggested FeSO4-induced cell death in V. parahaemolyticus be a ferroptosis differing from that in mammalian cells. Through transcriptome analysis, it was discovered that the exposure of FeSO4 disturbed considerable amounts of gene expression in V. parahaemolyticus including those involved in protein metabolism, amide biosynthesis, two-component system, amino acid degradation, carbon metabolism, citrate cycle, pyruvate metabolism, oxidative phosphorylation, and so on. These data suggested that FeSO4 was a pleiotropic antimicrobial agent against V. parahaemolyticus. Notably, FeSO4 was able to eliminate V. parahaemolyticus in salmon sashimi as well, without affecting the color, texture, shearing force, and sensory characteristics of salmon sashimi. Taken together, our results deciphered a unique ferroptosis in V. parahaemolyticus by FeSO4, and highlighted its potential in raw-fish products to control V. parahaemolyticus.

Marination increased tyramine levels in rainbow trout fillet strips packaged under modified atmosphere

Marinades are increasingly used to manufacture raw fish products. In corresponding meats, marinating is known to have a major effect on the composition of the microbiome, but the effect of marinating on fish is not known as well. This knowledge gap prompted our study of the microbial ecology and amine formation in marinated and unmarinated modified atmosphere commercially packaged rainbow trout fillet strips. According to our findings, marination increased the maximum concentrations (7–8 log CFU/g) of psychrotrophic bacteria by one logarithmic unit and led to 5 times higher average tyramine concentrations than the corresponding unmarinated product. Instead, trimethylamine concentrations were 30 times higher in the unmarinated product than those in the marinated one. According to the 16 S rRNA sequence analyses, lactic acid bacteria (LAB) predominated in the marinated strips one day after the use-by date, whereas in the unmarinated strips Fusobacteriaceae and LAB were the dominating taxa. Based on the culture-dependent analysis, Latilactobacillus fuchuensis was the prevailing LAB in both products. Since the subset of L. fuchuensis strains tested was able to produce tyramine in vitro, we hypothesise that the use of the acidic marinade activated the production of tyrosine-decarboxylating enzymes in L. fuchuensis and led to the increased tyramine concentrations.

Influence of geographic, knowledge and behavioral factors on Opisthorchis viverrini infection in the Northeast of Thailand

Objective: To determine the influence of geographic, knowledge and behavioral factors on Opisthorchis (O.) viverrini infection in the Northeast of Thailand. Methods: This cross-sectional study was conducted by using four datasets of years 2016 and 2017. Generalized linear mixed model was employed to analyze association between geographic, knowledge and behavioral factors and O. viverrini infection. Results: Totally there were 1 885 participants. The prevalence of O. viverrini infection was 10.03%. Geographic factors that showed statistically significant association with O. viverrini infection in the Northeast region were featured by at least a dam and reservoir (Adj. OR = 4.21, 95%CI: 2.49-7.13, P 50 dogs and cats per village (Adj. OR = 3.40, 95%CI: 2.17-5.31, P 50% of its areas (Adj. OR = 1.91, 95%CI: 1.04-4.01, P = 0.036), as well as low to moderate levels of knowledge (Adj. OR = 1.60, 95%CI: 1.32 to 1.94, P Conclusions: O. viverrini infection still remains a public health problem of the Northeast of Thailand. Geographic and demographic factors, knowledge, and consumption behaviors of raw fish products are significantly associated with O. viverrini infection.

Multiplex MPN-PCR for the enumeration of three major Vibrios in raw fishes in Malaysia

Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus are the most notorious fish borne-pathogens responsible for several deadly diseases in human. However, the prevalence of these three pathogenic vibrios in Malaysian fishes has not been thoroughly investigated, leaving a study gap for the tracing of possible Vibrio outbreak through carrier fish consumption. The most-probable-number-PCR (MPN-PCR) assays are highly sensitive for the identification of a single bacterial pathogen but they have not been applied for the discrimination of major vibrios in a multiplex platform. This study coupled MPN method with Multiplex PCR to differentiate three major vibrios in a one test platform. A total of 120 fish samples were analyzed and the prevalence of V. parahaemolyticus, V. cholerae, and V. vulnificus was 48.33%, 27%, and 32.50%, respectively. When simplex MPN-PCR was applied similar results were obtained at P < 0.05, validating the accuracy of multiplex MPN-PCR. The microbial loads of V. parahaemolyticus, V. cholerae, and V. vulnificus in the tested samples were 0–2.43 × 106, 0–2.16 × 106, and 0–4.93 × 105 MPN g−1, respectively. Primers based on housekeeping pntA gene amplified V. parahaemolyticus (409 bp) and V. cholerae (338 bp) but virulent vvhA gene detected V. vulnificus (205 bp). Thus the 27–48% prevalence of targeted vibrios in consumable fishes indicated there is considerable risk of Vibrio onset in Malaysia due to the consumption of undercooked or raw fish products.

Evaluation of Hygienic Quality and Labelling of Fish Distributed in Public Canteens of Northeast Italy.

Over the past few years, the demand for the introduction of fish products in public canteens (schools, hospitals and nursing-homes) has grown due to their good nutritional proprieties. The particular health conditions and sensitivity of some groups of consumers exposes them to greater risks of food poisoning. It is therefore important to monitor the raw materials that end up in mass catering implementing strategies of mass catering control, both with self-monitoring strategies and with regular controls performed by the competent health authorities. The purpose of this study is to assess the overall quality of seafood dealt out from public catering services located in Northeast Italy. In this paper we illustrate the results of microbiological analysis performed on 135 fish samples (58% of samples were raw fishes, 27% cooked fishes, 6% raw fish products, 9% cooked fish products) and species identification performed on 102 fish samples. Additionally, 135 environmental swabs were collected to determine the effectiveness of cleaning and sanitation of food contact (cutting boards, cooking equipment and food processing surfaces) and non-contact (refrigerator wall and handle, tap lever) surfaces. Of raw seafood samples, 24% had total aerobic mesophilic bacteria count >105 CFU/g and for Enterobacteriaceae the faecal contamination was excluded since no Salmonella spp. and Escherichia coli were isolated. Just 3.8% of raw seafood samples resulted positive for Listeria monocytogenes. The results of swab samples of cooking utensils and surfaces showed that sanitation practices should be improved. Molecular analysis for fish species identification revealed a mislabelling for 25% of sampled fishes. The results of this survey can provide valuable information for monitoring and surveillance programmes for the control of quality of fish and fish products.

Selection of Informative Spectral Wavelength for Evaluating and Visualising Enterobacteriaceae Contamination of Salmon Flesh

Enterobacteriaceae is one kind of harmful microorganisms commonly presented in raw fish products, and detection of Enterobacteriaceae plays a very important role in evaluating microbial contamination. This work was carried out to exploit the potential of emerging hyperspectral imaging technique to determine the Enterobacteriaceae contamination of salmon flesh during cold storage. The spectral information ranging from 900 to 1700 nm (239 wavelengths) was extracted to relate to the Enterobacteriaceae loads (recorded as log 10 CFU/g) using partial least square (PLS) regression, developing a PLS model with correlation coefficient of prediction (rP) of 0.94 and root mean square error of prediction (RMSEP) of 0.53 as well as residual predictive deviation (RPD) of 2.97. By applying successive projection algorithm (SPA), eight wavelengths at 924, 931, 964, 1068, 1262, 1373, 1628 and 1668 nm among the 239 wavelengths were selected as informative wavelengths to reduce the information redundancy and optimise the PLS model. With the eight informative wavelengths, a simplified PLS model defined as SPA-PLS was established with rP of 0.95, RMSEP of 0.47 and RPD of 3.23. To visualise the contamination degree of salmon flesh caused by Enterobacteriaceae, the SPA-PLS model was transferred to each pixel of images, and colourful distribution maps were produced with different colour represented different numbers of Enterobacteriaceae colonies. The results showed that hyperspectral imaging operating in 900–1700 nm is promising in evaluating Enterobacteriaceae contamination of salmon products. More studies are still required to further refine the multispectral imaging system to achieve online application.

Retention of shelf life and microbial quality of seer fish stored in modified atmosphere packaging and sodium acetate pretreatment

Abstract Preliminary shelf life tests were performed to select the best gas composition and the best sodium acetate concentrations in the modified atmosphere. Bacterial quality assessment was carried out by the monitoring of total aerobic bacteria, H 2 S producing bacteria, lactic acid bacteria, pseudomonads, Enterobacteriaceae, Staphylococcus aureus , streptococci, sulphite reducing clostridia and botulinum toxin by mouse bioassay. Bacteria grew most quickly in seer fish stored in air, followed by those in MAP and the lowest counts were with MAP pre-treated with sodium acetate. The application of sodium acetate treatment to seer fish steaks resulted in a bacteriostatic effect, contributing to the improvement of the microbiological quality of seer fish steaks. There was less trimethylamine in the modified atmosphere packed samples pretreated with sodium acetate than in air packed samples by the factor of seven, at the end of the shelf life. Modified atmosphere packaging alone increased the shelf life from 8 (air pack) to 22 days; however, addition of sodium acetate further extended the shelf life to 28 days. The results showed that the combined effect of MAP (70 vol.% CO 2 :30 vol.% O 2 ) and sodium acetate (1%, w/v) is a valuable tool to allow an effective extension of the shelf life of raw fish products.

Recovery of Anisakid larvae by means of chloro-peptic digestion and proposal of the method for the official control

Anisakidae larvae belonging to the genera Anisakis and Pseudoterranova, are the most responsible for zoonosis transmitted by fish products (anisakidosis). Acquired by the consumption of raw or undercooked marine fish or squid, the anisakid larvae may cause pathogenic diseases like gastric or intestinal anisakiasis and gastro-allergic disorders. In accordance with current EU legislation, the fresh fish products must be inspected visually in order to detect the possible presence of visible parasites. It is recognized that the visual method is not accurate enough to detect the larvae of parasites in food preparations containing raw or practically raw seafood and it clearly emerges that the official system of control needs to be able to utilise an most efficient analytical technique. In this work, the authors have drawn up and validated an analytical method, which involves artificial digestion and the use of a heated magnetic stirrer, based on the EU Regulation n. 2075/2005. The larvae isolated are then subjected to morphological identification at genus level by using optical microscope. The method, proved to be suitable for the detection of live and dead larvae of anisakidae in ready-to-eat foodstuffs containing raw fish or cephalopods and it is fast and accurate. The method showed high levels of sensitivity and specificity, and the suitability of its use in official food control was confirmed. Its use should be incorporated systematically into specific monitoring programs for the control of foodstuffs containing raw fish products.

Listeria monocytogenes prevalence and serotype diversity in various foods

The aim of the current study was to estimate the prevalence and serotype diversity of Listeria monocytogenes in various foods of Estonian origin such as meat, milk, fish, pastry, crop, culinary, fruit and vegetable with special reference to ready-to-eat (RTE) foods. In 2008–2010, a total of 554 (2.6%) of 21,574 food samples were positive for L. monocytogenes in Estonia. L. monocytogenes contamination was significantly (P < 0.001) higher in raw meat and raw meat products (18.7%), raw mixed salads (18.5%) and in raw milk (18.1%) compare to raw fish products (8.8%). Among RTE fish products, cold-smoked fish products were most frequently contaminated with L. monocytogenes (32.9%). Generally, the counts of L. monocytogenes in tested products remained under 10 colony forming units (CFU) per gram of product. Only 2.9% and 0.8% of the RTE fish products contained L. monocytogenes in range of 100–1000 CFU/g and >1000 CFU/g at the end of shelf life. The majority of tested isolates (73.6%) belonged to serotype 1/2a, followed by 1/2b (7.4%), 1/2c (7.4%), 4b (7.7%) and 4d (3.5%). Our findings showed that the prevalence of L. monocytogenes in various RTE food categories, in spite of higher prevalence among raw products, was generally low in Estonia.

Effect of modified atmosphere and active packaging on the shelf-life of fresh bluefin tuna fillets

The aim of this work was to study the influence of the combined use of MAP and antioxidant-based active packaging on the shelf-life of fresh bluefin tuna fillets stored at 3 °C. Active packaging films were produced by embedding α-tocopherol into an unstabilized low density polyethylene (LDPE) matrix at three concentrations (0.1%, 0.5%, 1%). α-Tocopherol release kinetics, in vitro antioxidant activity, oxygen permeability and crystallinity degree were determined to characterize the film. Preliminary shelf-life tests were performed to select critical quality indices, the best gas composition and the best α-tocopherol concentrations in the active film. Then, the effectiveness of the chosen active packaging film in combination with MAP was assessed by monitoring critical quality indices of fresh bluefin tuna fillet during storage at 3 °C for 18 days. Obtained results showed that (i) 100% N 2 atmosphere has a protective effect on haemoglobin and lipid oxidation processes monitored, (ii) active film is able to reduce fat oxidation, (iii) the combined effect of MAP and active packaging can be considered a valuable tool to increase the shelf-life of raw fish products.

Effect of sugars and polyols on the functional and mechanical properties of pressure-treated arrowtooth flounder ( Atheresthes stomias) proteins

The interest in safer raw fish products obtained by high pressure processing is increasing. However, the pressure (higher than 400 MPa) and time (1–5 min) needed to reduce the microbial load in muscle products denatures myofibrillar proteins and changes their mechanical, functional and visual properties. The objective for this study was to evaluate the stabilizing effect of sucrose, trehalose, sorbitol and their mixtures (1:1) on myofibrillar arrowtooth flounder ( Atheresthes stomias) proteins subjected to pressure treatments. Fish proteins solubilized with 2.5% salt and 4, 8 and 12% sucrose, sorbitol, trehalose or 1:1 mixtures of sucrose–sorbitol and trehalose–sorbitol were subjected to 600 MPa for 5 min. Texture profile analysis, protein solubility, heat induced gelling and color parameters were used to quantify pressure effects. Sorbitol at 8 and 12% was the most efficient stabilizing agent against high pressure effects on protein functionality.

Prevalence of and risk factors for IgE sensitization to Anisakis simplex in a Spanish population.

The number of allergic reactions to A. simplex reported in Spain has increased dramatically in the last decade. Nevertheless, there have been no studies of the prevalence of and possible risk factors for IgE sensitization to this parasite, possibly because suitably specific diagnostic methods have only recently become available. The objective was to investigate the prevalence of and risk factors for IgE sensitization to A. simplex in Galicia, a region of northwestern Spain with a population of about 3 million and high average fish consumption (78.5 g/person per day). The study was performed with a random sample of 2801 healthy blood donors distributed in 53 geographic areas, proportional to the density of donors. IgE sensitization to A. simplex was tested by a capture ELISA method that has proved to be the most specific method currently available. The results showed a total of only 12 positive subjects, of whom five also showed IgG1 sensitization. All positive subjects and 101 randomly selected seronegative subjects were then included in a case-control study of risk factors for sensitization to A. simplex, based on a telephone interview about fish consumption (especially raw and undercooked fish). All seropositive subjects (but only 25% of seronegative subjects) reported consumption of undercooked fish or homemade raw-fish products. Our results strongly suggest that sensitization to A. simplex is caused only by live larvae, and not by allergens contained in fish tissues, and that ingestion of homemade boquerones (anchovies [Engraulis encrasicholus] in vinegar), and to a much lesser extent of undercooked fish, are the main risk factors for IgE sensitization to Anisakis in this region.

Behavior and Viability of Third-Stage Larvae of Terranova sp. (Type HA) and Anisakis simplex (Type I) Under Coolant Conditions

This study reports effects of storage at cold temperatures on behavior and survival of third-stage larvae of Terranova sp. (type HA) and Anisakis simplex (type I) in marine fishes. Snappers, caught near the Hawaiian Islands, were examined to determine whether type HA and type I larvae could migrate from the viscera of ungutted fishes into edible musculature when maintained at 12, 8, and 0°C. Our data are suggestive that both type HA and type I larvae possess the ability to migrate. Temperatures of 12, 8, and 0°C had no noticable adverse affect on viability of both larval types within fish tissues; however, both larval types were extremely sensitive to temperatures below freezing. Death of both larval types encysted within Hawaiian snappers occurred by day 4 at −5°C and within 24 h at −10, −15, and −20°C. Other type I larvae, collected from fishes (Sebastes spp.) imported to Hawaii from the western Pacific, survived for slightly longer periods at −5, −10, −15, and −20°C when compared with type I larvae from Hawaiian fishes. Subjecting Hawaiian snappers to at least −20°C for 1 d and imported rockfishes to at least −20°C for 5 d is recommended to inactivate the living anisakines before ingesting any raw fish products.