A cod fillet and a cod loin come from the same fish, and the price gap between them is large. Understanding where it comes from makes it easier to decide which one your operation actually needs.
Where the loin is
A cod fillet runs the length of the fish. Its thickness is not constant: thick and even at the shoulder end, tapering through the middle, thin and irregular at the belly and tail.
The loin is the thick, even forward section. Cutting it means discarding — or redirecting — the thin belly flap, the tail piece and the irregular edges. What remains is uniform in thickness and free of the parts that cook at a different rate.
Why the price gap
Only part of each fillet becomes loin. The rest becomes portions, cuts, mince or by-product, each worth less per kilogram than the loin. The loin price carries the value the rest of the fillet gave up.
That is a genuine cost, not a margin decision. Which is why buying loin when a fillet would do is expensive, and buying fillet when the process needs a loin produces waste at your end instead of the supplier’s.
Choosing
Buy loin when portion consistency is critical, when the dish is plated whole, when a fixed cooking time is applied across a batch, or when a retail pack needs uniform pieces.
Buy fillet when you are portioning to your own spec and can use the whole side, when the product is coated or formed, or when the end use tolerates thickness variation.
Buy portions when you want the loin’s consistency without operating a cutting line, and the supplier’s tolerance matches your plating requirement.
Specifying a loin
Loin is not a standardised term across suppliers. Two things settle it:
1. A weight band per piece. Common market bands run 150–300 g, 200–400 g, 300–500 g, 400–800 g, 800 g+ and 1 kg+. Our own salted and smoked cod loin articles are cut to 120–140 g.
2. A definition of the cut. How far back the loin is taken, whether the belly is removed entirely, skin and bone status, and what thickness tolerance applies. A supplier’s “loin” and your “loin” are not automatically the same shape.
Add the glaze percentage and the net weight basis, and the specification is complete.
A note on haddock and saithe
The same anatomy applies. Haddock loins are thinner for a given fish weight and are more often specified by thickness than by weight. Saithe loins carry the dark muscle layer question — see the saithe specification for how to set the tolerance.