Last night I did a saute with shrimp in olive oil, garlic, lemon juice, a little butter - and I threw in some mushrooms.

The shrimp did not turn pink, or look really done. They firmed up a bit, as usual. And, while they became less opaque, they remained mostly gray. There was just a bit of pink on a few of the tails.

I nibbled a couple of them, and the were OK. But, I admit that the visual wasn't very appetizing, so I didn't eat them all. I had no untoward effect from what I did eat.

This is one of my "go-to" dishes for ease, and enjoyment. I've done it (how many?) times. I've never seen this.

The shrimp was the same brand that I always buy. It wasn't old ... I go through one of those bags fairly quickly. This was the last of the bag, and the others were fine. I haven't had a power outage that might comprise the freezer. The only difference is that I used a cast iron skillet, rather than stainless steel.

Any ideas?

I am very wary of seafood especially bought in supermarkets. Fortunately for me, I have a store dedicated only to seafood in proximity to my house. When I buy seafood, it is always fresh and from that store...expensive? Yes...but I don't want to take any chances. My older sister had a severe reaction to store bought shrimp that she purchased and prepared herself...

I don't think it's the cast iron, I've used cast iron with shrimp and they pinked right up.

This is a new one on me. The color change is caused by a chemical in the shrimp, so I supposed it could have reacted with something or other, but honestly, I can't find out a thing about it.

My suggestion is that you e-mail the company, since you know the brand.

Do you usually add mushrooms? If not, I would say it was the mushrooms. I made scrambled eggs one time and added mushrooms. The eggs turned gray, looked terrible, but still tasted good.

I've cooked shrimp with mushrooms, and never had a problem.

Fresh shrimp is suppose to change pink after cooked. Maybe that batch of yours was already spoiling.

I suppose. But, as I said, it was a frozen brand that I have been buying for years, and the bag wasn't more than 3-4 weeks old. The other shrimp that I had used from that bag were fine.

Garlic+acid=blue green pigments
Maybe your shrimp was painted