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Other from China, Japan, Korea, Thailand and Malaysia

Salt-alum jellyfish (boundary, not microbial)海蜇

Edible jellyfish are cured, not fermented. Fresh bells and oral arms are washed and soaked in rounds of salt and alum (aluminium sulfate salts), with less alum each round, until most of the water content is lowered and the soft tissue turns crisp and rubbery. The whole cure takes from 4 to 40 days, and no microbe does the work.

DocumentedOther8 days – 17 days

Recipe

No fixed amounts recordedRatios vary with the processor and the species and are not published as a recipe. The stages below follow a rural method from Sarawak, Malaysia, as summarised in Raposo 2022.
Fresh jellyfish, umbrella and oral armsProcessed within hours of catching, since they spoil fast[bleve2021]
Salt[bleve2021][raposo2022]
Alum (potassium or ammonium aluminium sulfate)The share of alum is lowered with each round[bleve2021]
Sodium bicarbonateAdded with the salt and alum in the Sarawak method[raposo2022]
Starternone (chemical dehydration)

Total time across the recorded steps: 8 days – 17 days

Start
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What changes: The jellyfish bell is cut from the arms and washed clean

Step 1 of 5
Separate the bell from the oral arms and wash
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented

Washing removes mucus, gonads, sand and bacteria. Both parts are processed for eating. Output: cleaned umbrellas and oral arms.

Flavour
Not documented
Texture
Not documented
Colour
Not documented

Microbes at work in this step

Not documented for this step.

Method

Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source

At a glance

Edible jellyfish are cured, not fermented. Fresh bells and oral arms are washed and soaked in rounds of salt and alum (aluminium sulfate salts), with less alum each round, until most of the water content is lowered and the soft tissue turns crisp and rubbery. The whole cure takes from 4 to 40 days, and no microbe does the work. Made in 5 steps over 8 days – 17 days. The longest step, wash with salt water, takes 3–7 days (Raposo A 2022). Salt is 25–27 % (Rakmae S 2020). None; salt and alum dehydrate and firm the tissue, and alum partly disinfects it does most of the fermenting.

Key numbers
Main step3–7 daysReported[raposo2022]Wash with salt water
Salt25–27 %Reported[rakmae2020]Drain and hold

What makes this one different

Unlike salted fish, nothing ferments or ripens. Alum metal ions probably cross-link the jellyfish collagen and salt pulls the water out, a chemical cure much like the alkali cure of century eggs.

Whole cure
Depending on the species and the treatment, processing lasts from 4 to 40 days

Related ferments

Safety

Not a fermentation; kept as a boundary entry. Aluminium from the alum is the main concern, since long exposure during processing, shipping and storage raises the aluminium content of the product. A review cites market samples in Shenzhen at 318–1000 mg aluminium per kg, with young children there above the tolerable intake. The EU tolerable weekly intake is 1 mg aluminium per kg of body weight and the JECFA figure is 2 mg. In a Tianjin survey the same review cites, jellyfish averaged 433 mg per kg against a recommended residue level of 100 mg per kg. The review also reports a few cases of anaphylaxis after eating jellyfish. Alum-free calcium-salt treatments have been developed for EU use. Fresh jellyfish spoil within hours and the ratios are not published, so read the stages below as a record of the trade, not a home recipe.

Hazards the sources name: Aluminium from the alum cure, not a microbe; market samples in Shenzhen held 318–1000 mg per kg (as cited in a review); Staphylococci and Vibrio species, in small numbers on Rhizostoma pulmo washed in sterile seawater before any cure.

History and sources

Every number is labelled with how it is known. How this atlas is made

Jellyfish are eaten mainly in East and Southeast Asia, where the crisp texture comes from the alum cure. Western interest is recent; in the EU jellyfish foods fall under novel food law.

  1. [bleve2021] Bleve G., Ramires F.A., De Domenico S., Leone A. 2021, An alum-free jellyfish treatment for food applications, Frontiers in Nutrition 8:718798paper
  2. [raposo2022] Raposo A., Alasqah I., Alfheeaid H.A. et al. 2022, Jellyfish as food, a narrative review, Foods 11(18):2773paper
  3. [rakmae2020] Rakmae S., Sooraksa P., Pornchaloempong P. 2020, Development of salt-sensing system for jellyfish desalting process, Sensors and Materials 32(2):521–530 (introduction)paper