Why was my pork so pink?

March 24, 2008 11:45 AM

Why did my pork roast turn pink?

Friday night I roasted a 2.5 lb boneless pork blade loin roast. I used a Cook's Illustrated recipe that calls for you to first sear the loin on the stovetop for about 10 minutes to brown the exterior and then to roast at 300 degrees for about 45-50 minutes or until 135 degrees. It was in the oven for about 70 minutes before my meat thermometer registered over 135 degrees (checked at several locations) and then I took it out and let it rest for about 20 minutes, covered in foil, still on the roasting rack but over a carving board.

The recipe suggests that the roast will continue to rise in temp while it's resting by about 10-15 degrees. (I never checked the temp again though and by the time we sat down to eat it, the roast was somewhat cooler.)

In the intervening 20 minutes or resting, the roast dripped a couple teaspoons of bright red juice and then when I carved it, the end pieces were noticeably pink. Not something you'd normally want to see in a pork roast. However, the middle pieces of the roast were much less pink. In fact, they looked pretty normal.

As far as I know, both the oven and my meat thermometer work fine and the roast was in there much longer than suggested. Why would only the (thinner) ends be pink while the (thicker) mid section was white? We actually ate some of the pink pieces and had no ill effects so I think it was fine, it just looked weird. However, I'm curious as to what was going on. I've heard that a lot of pork from the grocery store (I got this meat at Safeway) is injected with liquid to make it juicier, could that have played a part?

posted by otherwordlyglow to food & drink (11 comments total)

The center cooked more during the resting period, because of the foil covering, while the ends perhaps were less well covered, got more cool kitchen air flowing over them. What I do during the resting period is flip the roast right onto the carving board, cover with two sheets of foil so all parts are covered, and lay some towels or potholders on top for insulation. Your timing and temps are right, and you should get a nice juicy roast only slightly pink throughout. The injected liquid is not red, that would not be it.
posted by beagle at 11:58 AM on March 24

Possibly it was undercooked: most recipes I have require a temperature of 155 to 160 degrees before taking it out of the oven. It does go up 10 or 15 degrees while standing. Juices should run clear.
posted by francesca too at 12:03 PM on March 24

135 is low for a home cook of a pork roast - frequently you'll get 150+ suggested.

Its an excellent temp for about a med-rare pork roast though, and a little pink isn't the end of the world.
posted by bitdamaged at 12:08 PM on March 24

Yeah, agreed on the temps, I read that wrong. You should be roasting at 350, not 300. And get a temp of 155 or so.
posted by beagle at 12:20 PM on March 24

Funny, I cooked the exact same recipe yesterday, cooked to exactly 135'F and let it rise to 150'F on the counter top. It worked perfectly for me, as the recipe suggested. My instinct tells me, though, that it's highly unlikely that the thinner ends remained uncooked while the thicker middle cooked through all the way.

The first thing I would think about is the meat. Were the pink areas clearly undercooked, or did they just appear to be dyed pink? If they appeared colored or dyed, I would suspect exactly that, especially from a pre-marinated piece. It's not uncommon for them to use dyes in their injections to make meat look better on the shelf. Also, there's a chance that the manufacturer used some sodium nitrite in their injection, aka pink salt. It's a preservative that gives raw bacon it's characteristic pink color in the meat.

But this is all speculation. Other than that, I got nothing.
posted by slogger at 12:24 PM on March 24

Marinades and smoke will both turn pork pink.

If your roast was undercooked, you would have noticed the middle being undercooked, not the ends, so I'm voting for some kind of injected marinade, or something you marinated it in, if you didn't smoke it.
posted by rtha at 12:29 PM on March 24

It wasn't smoked and I didn't marinate it. I know that 135 is lower than what was once recommended but CI has a whole explanation about cooking temps for pork and I've read numerous accounts of how 155-160 is actually not recommended anymore as it results in super dry meat and the supposed risk of undercooked pork is much less of an issue than it ever used to be. I'm just baffled about the pink ends and the white middle.
posted by otherwordlyglow at 12:43 PM on March 24

I just wanted to chime in and say that a bit of pinkness doesn't necessarily indicate that the pork wasn't cooked enough. I generally roast mine to 137-ish and let it rest till it's about 150-ish. After having a few distinctly medium-cooked and quite pinkly-juiced pork chops in restaurants I realized that I really prefer it that way. If the juices are totally clear, I think that's a bit overdone for today's lean pork.
posted by mostlymartha at 12:43 PM on March 24

Is it possible that your oven cooks things unevenly? It's possible that the pork in the middle of the oven got cooked while the pork at the outer edges of the oven remained relatively raw.
posted by peacheater at 1:18 PM on March 24

Here's a USDA fact sheet about pink meat. Also, check out this article on myoglobin.

The upshot is that cooked meat can turn pink if it's exposed to nitrates, nitrites or carbon monoxide. The first two are usually found in cured meat but could conceivably have been in the store's marinade. Monoxide usually shows up during smoking, as in traditional barbecue, but I guess there might be other sources. The distribution — pinker towards the outside — sure sounds like the "smoke ring" you see in barbecued meat, where monoxide makes the myoglobin near the surface turn pink but leaves the color of the inside alone.

What was the texture of the pinkish meat like? Any juicier than the whiter meat? Did it have that rare-meat squishiness to it? Or did it feel and taste fully-cooked, and only look pink?
posted by nebulawindphone at 1:48 PM on March 24

From Howard McGheeOn Food & Cooking:

"The appearance of meat changes in two different ways during cooking...When heated to about 120°F/50°C it develops a white opacity as heat-sensitive myosin denatures and coagulates into clumps large enough to scatter light. This causes red meat color to lighten from red to pink, long before the red pigments themselves are affected. Then around 140°F;/60°C, red myoglobin begins to denature into a tan colored version called hemichrome. As this change proceeds,meat color shifts from pink to brown-gray.

...(Intact red myoglobin can escape in the meat juices;denatured browm myoglobin has bonded to the other coagulated proteins in the cells and stayed there)"

At the temperatures you were cooking at the recipe would have been relying on the temperature rising as it stood for the second reaction to take place. The thinner ends would cool quicker and therefore this reaction may not have been complete. If this is true then the red liquid would have been intact myoglobin escaping, which would lend further credence to this explanation. In addition McGhee mentions that when meat is heated slowly it can take a n hour or two to reach the necessary temperatures, at this point other proteins have already broken down so there is little for the myoglobin to react with so it stays intact and colours the meat red.
posted by tallus at 2:14 PM on March 24