Development and validation of Epagri’s vertical depuration system in terms ofreduction of Escherichia coli levels in oysters (Crassostrea gigas)

DOI: 10.52945/sbryde46
Published 2026-06-25

Authors

Abstract

Depuration is a process to reduce microbial contamination in bivalve molluscs, such as oysters, to acceptable levels for human consumption by keeping the animals in tanks with salt water. Depuration can only be carried out by establishments registered by the official inspection service. Conventional depuration systems occupy large floor areas, which limits their use in small processors. As an alternative, Epagri developed a compact vertical system, easy to construct, consisting of adapted fish crates stacked over a reservoir from which seawater is continuously pumped and disinfected by UV radiation. The efficiency of the system was evaluated in three 42-hour cycles with oysters. Initial levels of Escherichia coli, an indicator bacterium of fecal contamination, ranged from 330 to 3,300 MPN/100g, above the legal limit for live mollusks, thus requiring depuration. After 21 hours of treatment in the developed system, all samples showed levels below the legal limit of 230 MPN/100g, remaining within acceptable standards until the end of the trials. It is concluded that the vertical system developed optimizes space use, shows good performance in reducing E. coli, and has potential for application in small processing establishments.

References

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Keywords

  • Bivalve mollusk
  • Marine pollution
  • Public health
  • Aquaculture