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  • Author: Mirosław Michalski x
  • Molecular Biology x
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Abstract

One hundred and ninety seven samples of molluscs representing different species were tested for the presence of antibacterial substances using a microbiological diffusion test - “4-plate” method. It was found that 58 samples (29.4%) were positive. The percentage of positive samples depended on species and varied from 0 (Ostrea edulis, Perna canaliculis, Cardium edule, Myretrix lyrata, Mercenaria mercenaria) to 41.2 (Mytilus edulis) and 50.0 (Tapes semidecussatus and Ruditapes phillipinarium). The randomly performed confirmatory analyses using HPLC -MS/MS method did not show the presence of any known antibiotics.

Abstract

Introduction: Growing consumption of shellfish is associated with an increased risk of food poisoning. The study was carried out on live bivalve molluscs available on the Polish market between 2009 and 2013. Material and Methods: ELISA was used for the determination of the following marine biotoxins: paralytic shellfish poison (PSP), amnaesic shellfish poison (ASP), and diarrhoeic shellfish poison (DSP). The molluscs, of which seven species were examined, were obtained from wholesale companies and markets. Results: Marine biotoxins were detected below the permitted levels in 67.6% of the samples. The maximum amounts of PSP and ASP biotoxins were found in great scallops (532.6 μg/kg and 1.0 mg/kg respectively) and the peak for DSP was in blue mussels (107 μg/kg). Conclusion: The analysis of toxicological status of raw bivalve molluscs available on the market in Poland indicates that they are safe for consumers.

Abstract

Tetrodotoxin (TTX) is a toxin mainly occurring naturally in contaminated puffer fish, which are a culinary delicacy in Japan. It is also detected in various marine organisms like globefish, starfish, sunfish, stars, frogs, crabs, snails, Australian blue-ringed octopuses, and bivalve molluscs. TTX is produced by marine bacteria that are consumed mainly by fish of the Tetraodontidae family and other aquatic animals. TTX poisoning through consuming marine snails has recently begun to occur over a wider geographical extent through Taiwan, China, and Europe. This neurotoxin causes food intoxication and poses an acute risk to public health. The aim of this review is to present the most recent information about TTX and its analogues with particular regard to toxicity, methods of analysis, and risk to humans of exposure.

Abstract

The study was carried out on live bivalve molluscs available on Polish market. Samples of the molluscs (n = 124) were collected from warehouses and markets. Six different species of molluscs (mussels, oysters, vongole, scallops, Japanese clams, and razor clams) were used for the determination of saxitoxine (responsible for paralytic shellfish poisoning, PSP) by ELISA. The maximum concentration of PSP toxins (756.69 μg/kg of meat) was found in scallops. The majority of tested mussels were free from the PSP toxins or contained biotoxins bellow the permitted level (800 μg/kg). The analysis of toxicological status of raw bivalve molluscs available on Polish market indicated that they are safe for consumers.

Abstract

The study was carried out on live bivalve molluscs available on Polish market. Microbiological tests were performed for the presence of Salmonella sp., Vibrio parahaemolyticus, spore-forming anaerobe bacteria, and coagulase-positive Staphylococcus sp., and for the enumeration of Escherichia coli. ELISA was used for the determination of marine biotoxins, paralytic shellfish poisoning (PSP), amnesic shellfish poisoning (ASP), and diarrhoeic shellfish poisoning (DSP). Microbiological examinations were performed according to ISO and Polish Standards. Salmonella sp. was not detected in any sample tested. Coagulase-positive staphylococci were identified in 9.0% of the samples. V. parahaemolyticus was isolated from 17.0% of mussels. Shellfish were highly contaminated by anaerobes, which were isolated from 68.0% of the samples. The number of E. coli ranged from <2.0 x 101 up to >1.8 x 104 MPN/100 g. The majority of mussels were free from the marine biotoxins tested or contained them bellow the permitted level. The analysis of microbiological and toxicological status of raw bivalve molluscs available on Polish market indicates that they are generally safe for the consumers.

Abstract

A total of 85 mussel samples of eight species were examined. Analysis of mercury in the freeze-dried samples was carried out by atomic absorption spectrometry method using direct mercury analyser AMA 254. The analytical procedure for determination of mercury was covered by the quality assurance programme of research and participation in national and international proficiency tests. Concentrations of total mercury in all investigated samples were found to be generally low, in the range of 0.033-0.577 mg/kg of dry weight and of 0.003-0.045 mg/kg of wet weight. The results indicate that obtained levels of mercury in bivalve molluscs are not likely to pose a risk to the health of consumers.

Abstract

The high performance liquid chromatography with diode array detection was used for the study. The histamine was detected in 14.6% and 17.8% of the samples of fresh and smoked fish respectively. The highest concentrations of the compound were found in smoked herring and smoked sprat (17.7 mg/kg and 24.1 mg/kg respectively). Histamine concentration in fresh and smoked fish did not exceed the allowable limit, indicating that they are safe for consumers.

Abstract

Introduction

In recent years, there has been a great interest in biogenic amines such histamine, as they are associated with the quality and safety of some kinds of fermented foods. The aim of this study was to evaluate the effect of temperature and storage time on the content of histamine in cheeses.

Material and Methods

Samples of mould and hard cheeses were examined with RP-HPLC with an organic-aqueous mobile phase containing acidic buffer and chaotropic salt. The samples were stored either at 22 ± 2°C for 42 days (mould and hard cheeses) or at 4 ± 2°C for 112 days (mould cheeses) and 133 days (hard cheeses).

Results

The mean total histamine content in cheeses stored at 22°C was higher than the content in those stored at 4°C, with the highest concentrations found in Gorgonzola Piccante cheese (730.47 mg/kg). Histamine concentration in some types of cheeses exceeded the toxic threshold dose, indicating that after long or inadequately cool storage they may not be safe for consumers.

Conclusion

To protect cheeses from contamination with histamine-producing bacteria and to safeguard consumers from poisoning, factors conducive to this amine’s formation should be minimised during cheese processing. Suitable temperature and time during storage of cheeses are recommended to avoid the intoxication. Monitoring of this toxin in food is necessary to ensure safety of consumers.