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raw fish with metallic glisten

I ordered sushi this evening from a reputable NYC sushi restaurant, where I generally find the fish to be quite good. I'm particular when it comes to fish, especially raw fish. When the sushi was delivered, over an hour later, I unwrapped it to find that the salmon, in my smoked salmon avocado roll, had a metallic, bluish glisten to it. I've seen this once before, but only after I left raw fish in the fridge one day too long. I was surprised to see this on smoked fish. Any ideas what the cause of this may be? I'm assuming it's indicative of something not very good.

asked by ATG117 over 5 years ago
8 answers 11126 views
3639eee1 5e0d 4861 b1ed 149bd0559f64  gator cake
hardlikearmour

hardlikearmour is a trusted home cook.

added over 5 years ago

It could just be birefringence. This is part of a transcript of a Good Eats episode about tuna. I don't see why the same couldn't apply to salmon.

"Speaking of color, you ever notice the rainbow effect that sometimes appears on the surface of freshly cut tuna? It's not from age and it's not fat. It's birefringence.
[reading from a book] "*Anisotropism of the refractive index which varies as a function of polarization and fre ... " [gives up]
Here's the deal. This surface is pretty smooth. But, if you look closely, you'll see it's actually a vast landscape of parallel fibers. When cut, the reduced surface pressure coaxes microscopic beads of moisture to the surface, each one of which acts as an independent prism. When viewed in concert, they look like a rainbow."

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added over 5 years ago

Another possibility is if it was prepared with garlic, sometimes garlic can turn blue, so it might make the fish blue. I looked this up several times and found it is safe to eat. But I like hardlike armours answer better so plus one.

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added over 5 years ago

Birefringence... LOL HLA: your defining style of the word & description of the phenomenon just reminded me of a similar anecdote from Richard Feynman's book 'surely you're joking Mr Feynman'.. about the word 'Triboluminescence' (light emitted when sugar crystal are crushed)

8a5161fb 3215 4036 ad80 9f60a53189da  buddhacat
SKK
added over 5 years ago

Between HLA and Panfusine, I am getting an unexpected education in science! Love this foodpickle.

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boulangere

Cynthia is a trusted source on Bread/Baking.

added over 5 years ago

Fascinating, HLA. I've seen this, too, and ate the fish anyway and lived to tell the tale. Surely You're Joking, Mr. Feynman is one of my favorite books, Panfusine.

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added over 5 years ago

Hardlikearmour, I think you may have hit the nail on the head. It does look like a rainbow. I was having a hard time trying to describe the effect. "Rainbow glisten" would probably have been more accurate. Quite interesting. Thanks!

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added over 5 years ago

Also, the other time I've seen this, it was indeed with raw sushi grade tuna.

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added over 5 years ago

bacon does this too. Birefrengence happens more often with cured proteins. Smoked salmon I am guessing means lox, cured and cold smoked, because regular salmon rarely has this effect but tuna almost always does.