Why is sous vide steak brown on the outside?

When sous viding a steak, lets say at 130F for 90 minutes, the steak will be completely red on the inside. However, the steak will look a pale gray on the very outermost portion. The point of sous vide is to get the temperature throughout the meat to be even with the temperature of the water, so it shouldn't go above 130F. I didn't take a picture of my steak specifically, but the picture below is reasonably accurate to what I was seeing.

Raw, post sous vide, post sear

What is the difference in the meat on the inside vs the outside if it is not the temperature? Why is there this difference in color?

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Does meat brown with a sous vide?

Steak cooked completely sous vide will not have any browning on its surface, so this must be added afterward for improved flavor and texture. The stovetop is a great way to add a nice, well-browned crust to your meat.

Why is sous vide meat grey?

UPDATE: So it seems the reason was that the steak was too thin, and I seared it too much afterwards (without letting it cool off properly). Will try a thicker steak and update the result.

Why is my steak brown after cooking?

This darkening is due to oxidation, the chemical changes in myoglobin due to the oxygen content. This is a normal change during refrigerator storage. Beef that has turned brown during extended storage may be spoiled, have an off-odor, and be tacky to the touch and should not be used.

Is it OK if my steak turned brown?

Answer: The steaks should be fine. As the U.S. Department of Agriculture points out, it's normal for fresh meat to change color during refrigerator storage. For instance, it's common for beef to turn more of a brownish shade, due to oxidation.

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Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.

Images: Pixabay, Waldemar Brandt, James Wheeler, Artem Beliaikin