Raw Mussels Research Articles

Microplastic contents from maricultured and natural mussels

Results of this research focuses on microplastic contents (levels, type, size, colour) in maricultured and natural mussels (Mytilus galloprovincialis) from different Italian stocks. No significant differences were found among maricultured and natural stocks. All recovered MPs are filaments ranging within 750–6000 μm of maximum length (average values 1150–2290 μm). Feeding raw mussel could produce median MP intakes of 6.2–7.2 items/g w.w. Concerning human exposure by diet, both raw and cooked values are important. Some preliminary tests performed in this study evidenced that the cooking process determined lower MPs levels (−14%) in cooked tissues compared to raw ones, MPs were recorded in cooking water and were characterized by a lower size than in raw mussels. Results obtained by this study represent an important baseline on MPs level to evaluate environmental and human exposure risks by diet.

The recovery and molecular identification of HAdV-D17 in raw sewage and mussel samples collected in the Eastern Cape province of South Africa

Human adenoviruses (HAdV) are a common cause of clinical infections in South Africa. However, there is a lack of information regarding the prevalence and molecular identification of this virus in the environment. The objective of this study was to investigate the recovery and molecular identification of HAdV in sewage and mussel samples. All samples were subjected to transmission electron microscopy, viral DNA extraction and nested PCR amplification using adenovirus-specific primers targeting a conserved region of the hexon gene. Amplicons were cloned and sequenced and BLAST analysis revealed a closest matched sequence (98% identity) belonging to HAdV-D17.

Occurrence of methicillin-resistant Staphylococcus aureus in raw shellfish at retail markets in Malaysia and antibacterial efficacies of black seed (Nigella sativa) oil against MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) is a remarkable pathogen which causes nosocomial diseases worldwide. In this study, raw green mussel and cockle samples in Malaysia were collected and investigated for the occurrence of MRSA. A total of 80 samples were analyzed using phenotypic and molecular approaches. A assembling of the most probable number (MPN) with multiplex polymerase chain reaction (mPCR) technique was used to identify MRSA in the samples. The occurrences of S. aureus and MRSA in shellfish samples were 15% and 8.75%, respectively, with the microbial load from <3 to 12.2 MPN/g. MRSA isolates were tested for their sensitivity to 17 generally used antibiotic agents by using disc diffusion assay. All the isolates were resistant to amikacin and penicillin. However, sensitivity was recorded for cefoxitin, ceftaroline, chloramphenicol, ciprofloxacin, clarithromycin levofloxacin, linezolid, ofloxacin, quinupristin/dalfopristin, tetracycline and trimethoprim-sulfamethoxazole. Moreover, the antimicrobial activities against MRSA were evaluated using minimum inhibited concentration (MIC) and minimum bactericidal concentration (MBC). The findings revealed that the black seed oil acted as a potent inhibitor of MRSA. The lowest value of MIC and MBC of black seed oil against MRSA was 32.8 and 42.2 mg/mL, respectively. The detection of MRSA in this study deserves a public attention because shellfish are commonly eaten raw or partially cooked in Malaysia.

Influence of Thermal Preparation Method on Mineral Composition of Mussels

This study focuses on evaluation of the effects of 3 different thermal preparation methods (boiling, roasting, microwaving) on mineral concentrations of mussels from Bucharest market. The mineral content in raw and cooked mussel samples was evaluated by ICP-OES and relative humidity of raw and cooked mussels by thermogravimetry. Se level in microwaved samples was significantly decreased compared to raw and the other 2 cooked mussel samples. Zn concentration in raw samples was not significantly different compared to those in roasted samples. Fe level was insignificantly different between boiled and roasted samples and significantly lowers in microwaved samples. Ni, Pb, and Se levels were significantly higher in boiled samples, and Cd levels were insignificantly different reported to cooking method. The percentage of water loss during roasting was lower than the other 2 thermal preparation methods. Potassium concentrations in cooked mussels were higher compared to raw ones. Mineral concentrations were highest in roasted samples and heavy metal concentrations in boiled mussels.

The recovery and molecular identification of HAdV-D17 in raw sewage and mussel samples collected in the Eastern Cape province of South Africa

AbstractHuman adenoviruses (HAdV) are a common cause of clinical infections in South Africa. However, there is a lack of information regarding the prevalence and molecular identification of this virus in the environment. The objective of this study was to investigate the recovery and molecular identification of HAdV in sewage and mussel samples. All samples were subjected to transmission electron microscopy, viral DNA extraction and nested PCR amplification using adenovirus-specific primers targeting a conserved region of the hexon gene. Amplicons were cloned and sequenced and BLAST analysis revealed a closest matched sequence (98% identity) belonging to HAdV-D17.

In vitro bioaccessibility of the marine biotoxins okadaic acid, dinophysistoxin-2 and their 7-O-acyl fatty acid ester derivatives in raw and steamed shellfish

Okadaic acid (OA), Dinophysistoxins (DTX1 and DTX2) and their acyl-derivatives (DTX3) are marine toxins responsible for the human diarrhetic shellfish poisoning. To date the amount of toxins ingested from consumption of shellfish has been considered equal to the amount of toxins available for uptake by the human body. The aim of this study is to assess the OA, DTX2 and DTX3 fractions released from raw and steamed mussels and cockles into the digestive fluids (bioaccessibility) using a static in vitro digestion model. Higher bioaccessibility was found in mussels (86 ± 4%) than in cockles (59 ± 9%). A significant reduction of ester derivatives of OA and an increase of OA were observed in the bioaccessible fraction of mussel samples, suggesting that DTX3 undergo conversion into their more toxic parent compounds during human digestion. However, similar increase of DTX2 and reduction of the respective acyl derivatives was not observed. Steaming lead to significant reduction of OA and analogues bioaccessibility in both species even though increased concentrations of toxins are obtained after this treatment. Risk assessment based solely on DSP toxins occurrence in seafood can conduct to an overestimation of the exposure and lead to more conservative regulatory measures.

Mussel (Perna perna ) Processing by an Alternative Method and Packaging Under Modified Atmosphere to Improve Physicochemical and Microbiological Characteristics

An alternative method was proposed to cook shucked Perna perna mussel using an integrated cooking and vacuum-cooling system. The pasteurized samples were stored for 25 days at 3C under modified atmosphere (MAP) of 50% CO2/50% N2. Physicochemical and microbiological characteristics were evaluated over 25 days for the conventional (CP) and alternative processing (AP). Physicochemical characteristics showed no significant change over the period. Water loss was greater for AP (58.23%) than CP (13.6%) resulting in a product without exudation during storage. Vibrio spp. was detected only in fresh mussels and was eliminated during the heat treatment without recontamination after processing. The counts of mesophilic and psychrotrophic microorganisms decreased after the heat treatment and during storage; the average count was 102 CFU/g at the end of 25 days. The AP combined with the modified atmosphere was efficient to control exudation and microbiota of mussels stored over 25 days. Practical Application The shelf life of raw mussels is restricted to 2 days, and the cross-contamination during mussel processing is a reality in countries such as Brazil. Thus, an alternative process is presented in this study to improve the processing and storage conditions of cooked mussels that could be applied by seafood processing industries so that the cooked mussels have lower microbiological count beyond 15 days when compared to the conventional process.

Effect of the industrial canning on the toxicity of mussels contaminated with diarrhetic shellfish poisoning (DSP) toxins

The effect of canning in pickled sauce and autoclaving on weight, toxin content, toxin concentration and toxicity of steamed mussels was studied. Weight decreased by 25.5%. Okadaic acid (OA) and DTX2 content of mussel meat decreased by 24.1 and 42.5%, respectively. The estimated toxicity of the mussel remained nearly unchanged (increased by 2.9%). A part of the toxins lost by the mussels was leached to the sauce but the remaining part should have been thermally degraded. DTX2 underwent more degradation than OA and, in both toxins, free forms more than conjugated ones. This process, therefore, cannot be responsible for the large increments of toxicity of processed mussels –relative to the raw ones-sometimes detected by food processing companies. The final product could be monitored in several ways, but analysing the whole can content or the mussel meat once rehydrated seems to be the most equivalents to the raw mussel controls.

Effects of Heating on Proportions of Azaspiracids 1-10 in Mussels (Mytilus edulis) and Identification of Carboxylated Precursors for Azaspiracids 5, 10, 13, and 15.

Azaspiracids (AZAs) are marine biotoxins that induce human illness following the consumption of contaminated shellfish. European Union regulation stipulates that only raw shellfish are tested, yet shellfish are often cooked prior to consumption. Analysis of raw and heat-treated mussels (Mytilus edulis) naturally contaminated with AZAs revealed significant differences (up to 4.6-fold) in AZA1-3 (1-3) and 6 (6) values due to heat-induced chemical conversions. Consistent with previous studies, high levels of 3 and 6 were detected in some samples that were otherwise below the limit of quantitation before heating. Relative to 1, in heat-treated mussels the average (n = 40) levels of 3 (range, 11-502%) and 6 (range, 3-170%) were 62 and 31%, respectively. AZA4 (4) (range, <1-27%), AZA5 (5) (range, 1-21%), and AZA8 (8) (range, 1-27%) were each ∼5%, whereas AZA7 (7), AZA9 (9), and AZA10 (10) (range, <1-8%) were each under 1.5%. Levels of 5, 10, AZA13 (13), and AZA15 (15) increased after heating, leading to the identification of novel carboxylated AZA precursors in raw shellfish extracts, which were shown by deuterium labeling to be precursors for 5, 10, 13, and 15.

동결건조 진주담치 추출물의 항산화 및 DNA 손상 보호 활성

동결건조에 의한 진주담치의 생리활성의 변화를 살펴보고자 DPPH 라디칼 소거능, ORAC, CAC 등의 항산화 활성과 comet assay를 이용한 DNA 손상 보호능을 측정하였다. 생 진주담치 및 동결건조 진주담치에서 물 추출물을 제외한 에탄올과 메탄올 추출물에서 DPPH 라디칼 소거능을 확인하였고, 메탄올 추출물의 경우 동결건조에 의해 DPPH 라디칼 소거능이 증가하는 것으로 나타났다. 생 진주담치의 ORAC 수치는 물 추출물에서 가장 높게 나타난 반면, 동결건조 진주담치의 경우 메탄올 추출물에서 가장 높게 나타났다. 동결건조 후 ORAC 수치는 물 추출물에서만 유의적으로 감소된 반면 HepG2 세포의 라디칼 소거능(CAC)의 경우 물 추출물에서 유의적으로 증가하여 소거 대상 라디칼에 따라 항산화활성의 차이가 있는 것으로 나타났다. 생 또는 동결건조 진주담치는 모든 추출물에서 산화적 스트레스에 의한 DNA 손상을 억제하는 보호 효과가 있음이 밝혀졌고 동결건조에 의한 보호 효과는 유의적인 변화가 없는 것으로 나타났다. 결론적으로 진주담치는 물 추출물의 DPPH 라디칼 소거능을 제외하고는 모든 추출물에서 항산화 활성과 더불어 DNA 손상의 보호 효과가 관찰되었고 동결건조 가공처리에 의해서 그 활성이 크게 영향을 받지 않거나 추출물에 따라 오히려 활성이 증가함을 알 수 있었다. 이러한 결과를 바탕으로 우리나라에서 생산되는 진주담치의 식품 첨가물이나 기능성 식품 개발을 위한 생리활성 소재로의 가능성을 확인할 수 있었다.

A sensory and nutritional comparison of mussels (Mytilus sp.) produced in NW Iberia and in the Armona offshore production area (Algarve, Portugal)

A biometric, nutritional and sensory analysis of raw and cooked mussels comparing Mytilus sp. from the north-west coast of Portugal and Spain (Minho and Galicia, respectively) and the new offshore production site of Armona (Algarve, south Portugal) was carried out. In addition, multiple factorial analysis was performed to explore potential relationships between sensory attributes and nutritional content properties between the different mussels. Results showed that, at similar times of sale, biometrics of mussels from Armona and Vigo were similar and bigger than the remaining. Nonetheless, despite some similarities in proximate composition, mussels presented differences in lipid classes, fatty acid content and free amino acids profiles. These differences were not fully reflected in the sensory assessment by the panel, which were able to distinguish different production sites in raw specimens but displayed problems in discrimination these in cooked mussels. Some nutritional components were related to specific sensory sensations.

Validation of real-time PCR for detection of six major pathogens in seafood products

Abstract Seafood can pose a public health concern to consumers. It is often consumed raw and may be contaminated with several foodborne pathogens. In order to guarantee the safety of seafood, real-time polymerase chain reaction (PCR) protocols may be used as these enable results to be provided within 24 h. The first goal of our work was to develop real-time PCR protocols enabling the detection of six foodborne pathogens that may be present in seafood products ( Campylobacter jejuni , Campylobacter coli , enterohemorrhagic Escherichia coli , Salmonella spp., Vibrio parahaemolyticus , and Vibrio vulnificus ). The corresponding gene targets were: 50S/VS1 , rfbE , ttr , tlh , and vvp . A multiplex PCR was also developed to detect the virulence genes of V. parahaemolyticus : tdh and trh . A total of 420 bacterial strains belonging to four different genera/strains were used in this study. Sensitivity and specificity were always 100%, except in the case of Salmonella spp., where three strains were not detected by our PCR protocols. The second objective of our work was to assess the detection limit of our real-time PCR protocols on artificially contaminated seafood products (raw shrimps, cooked shrimps, and raw mussels), purchased in public stores. Six different levels of contamination were assayed in four replicates for each matrix. The real-time PCR protocols enabled a better level of detection than the ISO methods, except for Salmonella in raw shrimps and for V. vulnificus in shrimps (raw and cooked). The estimated level of detection was between 1 and 47 cfu/25 g sample for the ISO norms and between 1 and 315 cfu/25 g sample for the real-time PCR protocols tailored in our work. The real-time PCRs developed in our work allowed for good selectivity, sensitivity, and specificity. The sensitivity on seafood products was estimated at a level of 100%, except for Salmonella (97%). In the spiking assays, the levels of detection were lower with the real-time PCR protocol than those obtained with the ISO method. This was not the case for V. vulnificus in raw and cooked shrimps and for Salmonella in raw shrimps. These real-time PCR protocols appear to be good alternative methods for surveillance of seafood products to ensure the absence of foodborne pathogens. One additional conclusion is that laboratories have to use enrichment media that are compatible with those recommended by ISO standards. This may facilitate the isolation of the pathogen if the real-time PCR protocol gives a suspect positive signal during the first step of the seafood analysis.

Image analysis method to quantify the effect of different treatments on the visual meat/shell ratio of half‐shelled green lipped mussels (Perna canaliculus)

Aquacultured green lipped mussel (Perna canaliculus) is the New Zealand export leader of seafood in terms of weight. Different treatments shrink mussel meat differently and affect the consumer perception of half-shelled mussels. In order to quantify this, digital images of half-shelled green lipped mussels subjected to two postharvest treatments (ultrahigh pressure (UHP) and heat treatment (HT)) and raw controls were taken. The ratio of the view area of the meat to that of the shell (labelled as 'visual condition index' (VCI)) was measured using image analysis. A polygonal region of interest was defined on the image to depict the boundary of the meat and to calculate the view area. Raw mussels had a VCI of 85%. HT mussels had a much reduced VCI of 41%, indicating shrinkage of the meat due to heat. UHP treatment used as a shucking method resulted in a VCI of 83%. Since VCI is one measure of quality for the consumer, this quantitative method can be used in the optimization of shucking treatment (HT or UHP). VCI can be used to optimize postharvest treatments to minimize meat shrinkage. This method can also be applied to other shellfish such as oysters and clams.

Prevalence and Serotype Distribution of Listeria monocytogenes in Salted Anchovy, Raw Anchovy, and Raw Mussel Using IMS-Based Cultivation Technique and PCR

In the present study, a total of 150 samples including 50 salted anchovy, 50 raw anchovy, and 50 raw mussel samples collected from the retailers and small-scale producers in Samsun province from the Black Sea region of Turkey were analyzed; and 12% (6/50), 2% (1/50), and 2% (1/50) of the samples, respectively, were found to be contaminated with L. monocytogenes. According to the serotype distribution, six salted anchovy and one of the raw fish samples were contaminated with L. monocytogenes 1/2b (or 3b). In one raw mussel, both L. monocytogenes 1/2b (or 3b) and 4b (or 4d or 4e) serotypes were detected.

Seroepidemiology of Toxoplasma gondii Infection among Healthy Blood Donors in Taiwan

Toxoplasma gondii is an opportunistic, zoonotic pathogen with a worldwide distribution. There are large variations in the seroprevalence of T. gondii infection in different regions of the world. Although toxoplasmosis became a notifiable communicable disease in Taiwan in 2007, little is known about its epidemiology among the general population. This cross-sectional study aimed to survey the seroprevalence of T. gondii infection and its risk factors among healthy blood donors in Taiwan. Through collaborating with the Taiwan Blood Services Foundation, a total of 1,783 healthy blood donors from all six-branch blood service centers participated in this study. The blood samples were tested for the presence of T. gondii antibodies and DNA using enzyme immunoassays and real-time PCR, respectively. Structured questionnaires were used to gather information on risk factors for T. gondii infection. Of the 1,783 participants, 166 (9.3%) tested positive for anti-Toxoplasma IgG, while 5 (0.28%) tested positive for anti-Toxoplasma IgM. The five IgM positive donors had high avidity antibodies suggestive of past infection. No active parasitemia was detected by real-time PCR assays. Multivariate logistic regression showed that undercooked pork meat consumption (adjusted odds ratio [OR] = 2.9; 95% confidence interval [CI]: 1.3–6.5), raw mussels consumption (adjusted OR = 5.3; 95% CI: 1.5–19.1), having a cat in the household (adjusted OR = 2.0; 95% CI: 1.2–3.2), a lower education level (adjusted OR = 1.6; 95% CI: 1.1–2.3), and donation place in eastern Taiwan (adjusted OR = 2.5; 95% CI: 1.6–3.9) were independent risk factors for Toxoplasma seropositivity. These findings provide information on the seroprevalence and epidemiology of T. gondii infection among healthy blood donors in Taiwan.

Latent Toxoplasmosis gondii: Emerging Evidence for Influences on Neuropsychiatric Disorders

Toxoplasmosis gondii (T. gondii) an intracellular parasite discovered in 1908, is present in about one-third of the world’s population; once infected, hosts remain seropositive for life. (Known exposure risks are feline feces; raw or undercooked meat; raw oysters, clams, and mussels; and unwashed raw fruits and vegetables.) Various studies worldwide have found personality/adjustment difficulties, such as increased anxiety, in otherwise-healthy seropositive individuals, and seropositivity in schizophrenia patients was found to be almost three times that of a control population. Unlike the acute form, chronic latent T. gondii infection resides in intact neurons; and there is considerable variation in findings of structures affected, although there does appear to be a predilection for dopaminergic neurons.

Implicit price of mussel characteristics in the auction market

This study explores desired and undesired characteristics of mussels in wholesale market by applying hedonic price analysis. Transaction data in auction market in Yerseke, the Netherlands, was used to estimate linear and semi-log price models. Meat content and size count, which are measured as the ratio of the weight of cooked meat to the total weight and the number of mussel per kg of raw mussels, respectively, are the most important characteristics determining the price. At the sample mean, if the meat content increases by 1%, farmers can get a premium price of 5.5 eurocents kg−1 of raw mussel. Mussel lots with size counts below 50 pieces kg−1 can command the highest implicit price of size. Processors prefer mussel lots in which the size of mussels is more or less heterogeneous. The impurity of mussel lots, which is measured by the percentage of tare, the amount of barnacles and limpets per kg of raw mussels are significant discounting factors on the price. The study also investigates the impact of farming locations and seasons on the price and the price trend during the period of 2002–2009.

Determination of Fatty Acid Methyl Esters in Biodiesel Catalyzed by Shell based on Gas Chromatography

In order to analyze the content of fatty acid methyl esters, biodiesel was analyzed by gas chromatography method. Biodiesel was produced from the raw materials soybean oil and mussel shell catalysts. GC analysis was developed by using HP-innowax chromatographic column and FID detector. Undecanoic acid methyl ester was chosen as internal standard solution. The results show that five kinds of fatty acid methyl esters were linear at range 4 g•L-1～31 g•L-1 (γ≥0.9928). The average recovery rate was 98.28%～101.85%, and relative standard deviation was less than 0.31%. The coefficient of variance of precision was less than 1.59%. This GC method is simple, rapid and accurate and it will be the base for further research.

Utilisation of waste material for environmental applications: calcination of mussel shells for waste water treatment

Waste mussel shells from the New Zealand aquaculture industry have been investigated as a potential source of lime for use in waste water treatment. The calcination of raw mussel shells to lime was studied as a function of particle size, temperature, heating rate, treatment time and atmosphere. Lime formation went through a maximum with respect to particle size for all heating conditions, as a result of competition between increased surface area and a tendency for particle to form necks resulting in caking. Optimised heat treatment conditions resulted in transformations of more than 95%. Preliminary experiments to investigate removal of phosphates from model waste water solutions showed that raw shells had limited ability due to a mechanism that relies on adsorption only. For these raw materials the finer particle sizes removed more phosphate due to increased surface area. The heat treated mussel shells on the other hand were shown to remove greater than 95% of the phosphates for both fine and coarse size ranges due to a precipitation mechanism of phosphate removal. This work demonstrates the potential for using mussels as an alternative to limestone for phosphate removal, at the same time overcoming the expensive and problematic issues of waste disposal.

Occurrence of Vibrio vulnificus in mussel farms from the Varano lagoon environment

Monitoring the occurrence of the human pathogen Vibrio vulnificus in a mussel farm located in the lagoon of Varano (Italy). A total of 72 samples of mussel, water and sediment, collected from two locations of Varano lagoon in the Gargano peninsula, during a 7-month survey, were analysed. Isolation and PCR characterization of six V. vulnificus environmental genotype strains revealed that this pathogen was isolated when with T was above 22 °C and salinity ranged between 22.7 and 26.4‰. No significant correlation of the occurrence of V. vulnificus with water pH or salinity was observed. Moreover, 8% of mussel samples were found to be contaminated by V. vulnificus. All of that positive mussel samples originated from the same sampling station. It is suggested that warmer season are risky to eat raw or undercooked bivalve molluscs in the local area. To increase knowledge about environmental conditions that may affect the occurrence of waterborne pathogen Vibrio vulnificus in seafood.