Sous vide burgers don't turn brown?

Matt_118984

I just bought an Anova immersion circulator.

The other night, I cooked three hamburgers using the Ziploc method in 140F water for about 50 minutes.

As soon as I pulled the burgers out of the water, I stuck a Thermapen in one and it registered about 136F, which translates to medium rare. I then pan-seared the burgers.

After pan-searing, I cut one burger open and it was completely pink, as if very rare. The texture was pretty firm (much firmer than it looked), and the flavor was great.

I'm confident the burger was cooked (I haven't gotten sick or anything, and 136F is 136F...), but I'm confused as to why the burger was so pink. I have friends who like things medium well and well done, so I want to be able to explain the pink.

Can anyone explain it to me? From what I've read, taking oxygen away from myoglobin by vacuum packaging and/or cooking turns meat brown...so how did the pink happen?

Thanks.

Angelo_197648

It'll be more gray than brown, and the inside of the beef isn't going to go that color until I think over 145/150-ish if you cook sous-vide because of the lack of the mallard reaction.