· Shishi G-Shield Seafood Technology Co., Ltd
Individual quick freezing and block freezing are not quality grades. They are two answers to the question "who is going to portion this fish, and with what". Choose the wrong one and you pay for it in labour, yield or thaw loss long after the invoice is settled.
What the two methods do
IQF freezes each piece separately, in a tunnel or on a fluidised bed, so pieces stay loose in the carton. Block freezing packs product into a mould or a plate freezer and freezes it into a solid slab before glazing and cartoning. Both reach the same storage temperature; they differ in how the product comes out of the box.
IQF: you buy convenience and pay for it
Loose pieces mean you take what you need and put the rest back. That matters for retail packs, for food-service portioning, and for any line where the operator is not running a bandsaw. The cost shows in the price per kilo: IQF uses more energy and more floor space per tonne than block freezing, and yield is lower because every piece carries its own glaze surface.
Block: you buy density and a saw
Block is cheaper per kilo and takes less space in the container and the cold store. It suits further processing (surimi, canning, mince, battered products) where the fish will be broken down anyway. The catch is that breaking a block needs equipment and a tempering step, and that step is where inexperienced operations lose yield: cut a block too cold and it shatters, cut it too warm and it loses drip.
The glaze question sits underneath both
A declared 10% glaze is roughly 100 g of ice per kilo, and that water has to be measured the same way on both sides of the contract. On IQF product the glaze is per piece and can be checked on a sample; on a block it is on the outside of the slab, so the interior of a badly glazed block can be unprotected. State the percentage and the basis: is the declared net weight before or after glaze? That one line prevents most arrival claims we see.
How to write it into a specification
Name the method explicitly ("IQF, loose in 10 kg carton" or "block frozen, 2 × 10 kg per carton"), then add the tolerance you will accept on piece count and on glaze. If you repack at destination, say so: it changes which method is cheaper for you, and it is the kind of detail a supplier can only price correctly when it is on the enquiry.