{"id":474,"date":"2026-10-01T07:05:32","date_gmt":"2026-09-30T22:05:32","guid":{"rendered":"https:\/\/magazine.samsammulsan.com\/glossary\/how-do-shellfish-depuration-seawater-treatment-and-shucked-oyster-meat-washing-differ\/"},"modified":"2026-10-02T11:05:57","modified_gmt":"2026-10-02T02:05:57","slug":"how-do-shellfish-depuration-seawater-treatment-and-shucked-oyster-meat-washing-differ","status":"publish","type":"glossary","link":"https:\/\/magazine.samsammulsan.com\/en\/glossary\/how-do-shellfish-depuration-seawater-treatment-and-shucked-oyster-meat-washing-differ\/","title":{"rendered":"How Do Shellfish Depuration, Seawater Treatment, and Shucked Oyster Meat Washing Differ?"},"content":{"rendered":"

Shellfish depuration, seawater treatment, and shucked oyster meat washing are processes with different targets and records. If all of these are referred to simply as “seawater purification,” it becomes difficult to ascertain which raw materials underwent which treatment, potentially leading to misjudgment of management effectiveness.[1]<\/a><\/p>\n

\"Workers<\/p>\n

Washing stage in the Eoriguljeot (salted fermented oysters) manufacturing process, provided by Samsam Moolsan. This is an example of a process handling shucked oyster meat, distinct from the depuration of live shellfish.
Photo courtesy of Samsam Moolsan \u00b7 <\/a>Original image provided by the company<\/a><\/p>\n

Distinguishing the targets and documentation for the three processes<\/h2>\n
\n\n\n\n\n\n\n
\n

Category<\/p>\n<\/td>\n

\n

Target of Treatment<\/p>\n<\/td>\n

\n

Primary Purpose<\/p>\n<\/td>\n

\n

Operational Data to Verify<\/p>\n<\/td>\n<\/tr>\n

\n

Shellfish Depuration<\/p>\n<\/td>\n

\n

Live Oysters\/Clams<\/p>\n<\/td>\n

\n

Elimination\/Reduction of Some Microbial Contamination<\/p>\n<\/td>\n

\n

Raw material lot, tank, water temperature\/salinity\/oxygen, time, loading, water flow<\/p>\n<\/td>\n<\/tr>\n

\n

Seawater Treatment for Processing<\/p>\n<\/td>\n

\n

Intake Seawater<\/p>\n<\/td>\n

\n

Management of Process Water Suitability (e.g., wash water, tank water)<\/p>\n<\/td>\n

\n

Intake source, filtration\/UV\/ozone, water quality, equipment operation<\/p>\n<\/td>\n<\/tr>\n

\n

Shucked Oyster Meat Washing<\/p>\n<\/td>\n

\n

Shucked Oyster Meat<\/p>\n<\/td>\n

\n

Removal of Sand, Mud, Shell Fragments<\/p>\n<\/td>\n

\n

Wash water, contact time, sorting, drainage, weight<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Depuration utilizes the filtration and excretion activities of live shellfish, thus requiring management of the tank environment. While treated seawater can be supplied to the tanks, water treatment records alone cannot prove the completion of oyster depuration. Shucked oyster meat does not filter, so washing is not depuration. For information on which stages apply to which products, refer to the Oyster Processing Process Branching Guide<\/a> and verify with actual process flow diagrams.<\/p>\n

Depuration is applied within official management and raw material eligibility.<\/h2>\n

Codex distinguishes between direct harvesting from approved areas and, if necessary, relaying or depuration under the control of the competent authority.[2]<\/a> Depuration does not permit the distribution of raw materials with unclear origins or those not approved for use. Please verify the production area, raw material lot, applicable SKU, depuration conditions, and release judgment together.<\/p>\n

Reflect Removal Limitations in Use and Labeling<\/h2>\n

Depuration can reduce many fecal bacteria but is less effective against Norovirus and Hepatitis A virus. It may also have inconsistent or ineffective removal effects on marine Vibrio, shellfish toxins, heavy metals, and organic chemicals.[1]<\/a> Similarly, UV seawater treatment does not guarantee that all hazards in oyster tissue have been eliminated.<\/p>\n

To compensate for these limitations, it is necessary to consider production area control, harvesting restrictions, raw material\/lot verification, cold chain distribution, labeling for intended use, and necessary heating. Norovirus monitoring in production areas and labeling for cooking purposes are also origin management practices operated separately from depuration.[3]<\/a> When reviewing hazards and records at each stage, you can refer to The Role of Seafood HACCP<\/a>.<\/p>\n

Verify Supply Descriptions with Records<\/h2>\n