Single frozen means the product was frozen once, from fresh raw material, and has not been thawed since. Double frozen means it was frozen, thawed for a processing step, and frozen again.
Both are legitimate. Double freezing is how a great deal of the world’s whitefish is filleted: fish is frozen at sea in whole or H&G form, shipped to a processing plant, thawed, filleted, and refrozen as a finished product. Without that route, a lot of product would not exist.
What is not legitimate is failing to declare it.
What actually changes
Every freeze forms ice crystals inside the flesh, and every crystal does a small amount of mechanical damage to cell structure. Thawing releases the liquid those cells held. Freeze a second time and the process repeats on tissue that has already been damaged once.
In practice this shows up as:
- Higher drip loss on thaw — you are paying for water that leaves the product in your kitchen.
- Softer texture, which matters more for a grilled fillet than for a fish cake.
- Reduced yield through a portioning or coating line.
- Shorter usable life after thaw.
None of this makes double-frozen product bad. It makes it different, and it should be priced differently.
Why it disappears from contracts
Freezing history is not visible in a frozen carton, it is not implied by any grade or trim letter, and it does not appear on most standard specification templates. The result is that it is frequently the one material attribute nobody wrote down.
How to ask
Put it in the enquiry as a required field, not a question:
Freezing history to be declared: never frozen / single frozen / double frozen. Where double frozen, state where the intermediate thaw took place.
And ask for the production date alongside it. Freezing history and time in frozen storage are related questions, and knowing one without the other tells you less than you think.
The related question: where was it frozen?
Separately from how many times, ask where. Frozen-at-sea product goes from capture to −18 °C within hours aboard the vessel. Shore-frozen product is landed first and frozen after handling on land. Both can be single frozen. See fresh and frozen-at-sea whitefish.