Why Do Langoustines Sometimes Turn Blue? (And Is It Safe to Eat?)

If you’ve ever defrosted a tray of langoustines and noticed a blue or greenish tint in the flesh, you’re not alone. It can be a little surprising at first, but the good news is, it’s completely natural and nothing to worry about.

So, what causes the blue colour?

Langoustines are a bit different from most seafood. Instead of iron-based blood (like we see in many fish and meats), they have a copper-based blood pigment called hemocyanin.

When langoustines are processed, especially when the heads are removed, some of this pigment can come into contact with the flesh. During freezing and defrosting, this can sometimes show up as a blue or greenish hue.

It’s simply a natural reaction and part of how the product has been handled and preserved.

Is it safe to eat?

Absolutely 

The colour might look unusual, but it does not affect the quality or safety of the langoustines at all.

As with any seafood, the key things to check are:

A fresh, clean smell (not overly fishy or sour)

A firm texture

Proper storage and defrosting

If those are all good you’re good to go.

Does it affect the taste?

Not at all.

The flavour remains exactly what you’d expect, sweet, delicate, and delicious. Once cooked, the colour typically becomes less noticeable anyway.

The takeaway

That blue tint?
It’s just science doing its thing.

So next time you see it, you can cook with confidence knowing your langoustines are fresh, safe, and ready to enjoy.