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The presented study focused on the accumulation and persistence of potentially pathogenic Vibrio spp. accumulating in specific tissues of Mytilus edulis. Experiments were carried out on a laboratory scale in order to imitate the uptake of Vibrio spp. in mussels under controlled environmental conditions, monitoring the concentration changes of Vibrio during the various studies.
The aim of mussel contamination tests was to evaluate the behavior of Vibrio spp. in mussels after artificial contamination. Various studies highlighted high loads of Vibrio spp. in mus-sels, other seafood and mussel farming areas. Thus, three research strategies were performed investigating contamination, clearance and storage.
Contamination assays showed that Vibrio accumulates within 1.5 hours in digestive glands, up to concentrations of approx. 107 CFU/g to 108 CFU/g.
Clearing experiments over a period of seven days showed a slow continuous reduction of Vibrio concentrations, however Vibrio were detected during the whole investigation periods. A decrease rate of 0.02 log CFU/g per hour was found by tracing of Vibrio spp. concentra-tions in the digestive glands of Mytilus edulis.
Storage experiments were performed over a period of ten days after 24-hours of contamina-tion. Mussels were packed according to retail conditions (in jute bags and vacuum bags in-cluding 200 ml of ASW). The persistence of Vibrio spp. were achieved at 3°C in melting ice and at 15°C in a refrigerator. It was shown that under storage V. cholerae and V. parahaemolyticus counts were stable. Only fluctuations in the range of 2 log stages were detected. However, V. vulnificus concentrations declined slowly but steadily.
Mytilus edulis accumulates Vibrio rapidly to high numbers, clearance kinetics are slow and eradication of Vibrio seems slow whereas storage conditions keep Vibrio alive with stable counts.
The present study confirms that within mussels Vibrio concentrations can be achieved, which are dangerous to human health, if mussels were consumed raw or only partially cooked. Espe-cially the maintenance of the cold chain from catch to counter is crucial to avoid a possible multiplication of Vibrio in seafood.