From Fish to Tin: How Caviar Is Made

Individual eggs pass through a screen; larger pieces of the membrane that held them together stay behind. This delicate separation begins the transformation of conventionally collected sturgeon roe into caviar. Cleaning, grading, salting and packing follow, each operation protecting the beads while keeping a highly perishable food safe. The journey depends on three essentials: gentle handling, measured salt and an unbroken cold chain.

How caviar is made, step by step

Egg collection comes first, as covered in harvesting step by step. The sequence below follows conventional granular caviar processing, with separate notes on ovulated eggs, pasteurisation and later repacking.

1. Receive the roe and keep it cold

Cold handling starts on arrival. Roe, meaning fish eggs, is checked for suitability as it reaches the processing area and kept chilled throughout the work, not left waiting on a bench. Time at warmer temperatures allows microbes to grow and quality to deteriorate. Neither careful salting nor immaculate packing can undo damage earlier in the chain.

Codex processing guidance calls for monitoring exposure time and temperature, with caviar kept at 4 °C (39.2 °F) or below during packing. This is a processing control, distinct from a serving temperature. Codex does not give a universal number of minutes from harvest to sealing.

2. Screen, rinse and drain

The membrane must come away without crushing the beads it holds together. Conventionally collected roe still carries this ovarian membrane. Workers gently rub portions over a screen, allowing individual eggs to pass through while larger pieces of membrane remain behind. Broken eggs and tissue fragments are removed, leaving intact beads for the next stage.

The loose eggs are rinsed in chilled clean water, then drained before weighing and salting. Codex also permits ovulated eggs from farmed sturgeons: eggs already released from their follicles. This method is subject to adhesive layer removal, shell hardening and approved hormone use, so membrane separation is not identical in every production method.

3. Assess and sort the eggs

Processors assess bead size, colour, firmness and the condition of the eggs, then group suitable batches according to their commercial specifications. A larger bead and a paler bead describe different qualities; neither establishes how well the roe was handled. Names such as Royal or Reserve belong to trade grading, rather than a standardised legal ladder.

These assessments explain why batches from the same species may remain separate. The processing hub places grading alongside the other decisions made before packing.

4. Weigh, salt and mix gently

Salt is weighed, not guessed. Food-grade salt is measured against the prepared roe and carefully mixed through it. The Codex Standard for Sturgeon Caviar, CXS 291-2010, specifies 3 to 5 g of salt per 100 g of finished product. That figure describes the final salt content, rather than an instruction to add the same percentage to wet, undrained eggs.

For preservation, processors also distinguish total salt from water-phase salt: the concentration in the product's water, rather than its whole weight. The figures are not interchangeable. Laboratory checks and a validated process matter more than a marketing description, and trained processors assess the roe using measured, controlled formulations. Taste alone cannot establish that preservation is safe.

Salting methods explain this balance, while malossol means lightly salted, not salt-free. Where optional preservatives form part of the formulation, their use depends on the market:

• EU and Northern Ireland: EU Regulation (EC) No 1333/2008 permits boric acid (E284) and borax (E285) in sturgeon caviar up to 4,000 mg per kg expressed as boric acid.
• Great Britain: the register also lists them.
• US: readers should check the FDA's current position.

See the salting formulation.

5. Fill the original production container

The salted roe goes into its first production container, commonly a lined metal tin, though a suitable glass jar or another food-grade container may also be used. A large original tin is often called a mother tin. It is a familiar part of production, rather than a compulsory stop for every batch.

Some documented tin filling uses gentle pressing to expel trapped air. Codex guidance calls for minimising air space without applying pressure to the eggs, with trained staff carrying out the appropriate vacuum and sealing operations. Less air helps limit oxidation. Sealing, however, is not sterilisation.

6. Apply the traceability label

The label connects the caviar to its production records. Under the CITES universal labelling system, the processing plant applies a non-reusable label to the original primary container: the receptacle directly touching the caviar, not its outer presentation box. The original code identifies species, source, country of origin, harvest year, processing plant and lot.

Neither careful salting nor immaculate packing can undo damage earlier in the chain.

The CITES caviar code provides traceability, rather than independent verification of the species or origin inside. CITES sets the international framework, implemented and enforced through domestic legislation in each jurisdiction, including EU Regulation (EC) No 865/2006 and US 50 CFR 23.71.

7. Chill and allow the salt to equilibrate

Salt keeps moving through the caviar after packing. Codex processing guidance gives an example of 24 hours at 2 to 4 °C (35.6 to 39.2 °F) to help initial salt absorption and equilibrium. This is an example of that early stage, not a fixed maturation schedule. Flavour development during longer storage is a separate production decision.

Maturation in the tin explores that later stage. Cold-storage conditions and shelf life must follow the processor's validated specification for the particular product, container and preservation method, rather than a single timetable applied to all caviar.

8. Pasteurisation and later repacking

Some caviar receives a controlled heat treatment after sealing, followed by cooling. This optional pasteurisation can change flavour and firm the eggs. Codex guidance requires the treatment to account for the container's size, shape and material, the amount of caviar and the equipment used. It does not prescribe a single kitchen-style heating time.

Later, a registered repacker may transfer the caviar into smaller primary containers under controlled conditions. The new label records the repacking details and retains the original country of origin. Moving roe into a new tin does not give it a new origin. Mother tins and repacked tins explains the distinction between first packing and this later transfer.

Hygiene underpins every stage

Safety comes from the whole system, not the appearance of the finished tin. That system includes suitable water, cleaned and disinfected equipment, staff hygiene, separation from contaminating operations, controlled temperatures and documented checks.

HACCP, hazard analysis and critical control points, identifies significant hazards and the controls needed to manage them. For packed caviar, these include pathogens such as Listeria monocytogenes and Clostridium botulinum, controlled through a validated combination of processing, formulation and storage. A pleasant smell, good appearance or intact seal cannot establish safety. Gloves and a cold room are only parts of the complete system.

Which processing rules apply?

The producing country and destination market determine the food rules a processor must meet. Codex provides an international reference standard for granular caviar made from Acipenseridae, the sturgeon family, but is not automatically binding law. Neither a Codex-compliant formulation nor a CITES label replaces those food rules.

Start with the jurisdiction: the table below brings together the main processing frameworks and what each covers.

These frameworks cover processing, rather than a complete import checklist. China's recommended processing specification sits alongside its wider body of binding food-safety law. Russia's listed framework is a Eurasian Economic Union instrument, not a rule shared by all caviar-producing countries.

Where to go next

• Caviar Processing: explore individual operations, including screening and heat treatment.
• The CITES Caviar Code Explained: distinguish origin information from the identity of a processor or repacker.