The Changing Color of Raw Beef

If you’ve ever purchased a cut of meat and left it in your refrigerator for a few days, you’ll notice that it goes from that nice bright red color to a darker browner color. For the longest time I thought that when it turned that dark brown that the meat was on the verge of going bad, sort of like a color coding for the meat, but that’s not the case. The color is an indication of the freshness of the meat because it’s like a measure of how long it’s been exposed to oxygen (it’s oxidizing), which explains why it’s still nice and pink on the inside if you cut it.

Basically, there is a pigment in the meat called myoglobin, the redder the meat the more myoglobin there is in the meat. Beef has more myoglobin than pork and chicken, hence the redder color. “Dark meat” chicken is more muscular, so it has more myoglobin and thus it’s darker.

Myoglobin is the starting point for the pigment in meat and when you or your butcher cuts off that piece of meat then the myoglobin is exposed to air, oxygenates, and forms what is called oxymyoglobin. In beef, it’s like a bright red, the color of the meat you usually find in the supermarket if it doesn’t have a $1 or $2 off sticker on it! (It’s that pink color in pork) Further exposure to the air, over the course of a few days, and the oxymyoglobin oxidizes and becomes metmyoglobin. Not being a science major of any kind, I have no idea what the met- prefix in metmyoglobin means but it gives the meat that brown color.

So, if it’s bright red in beef or bright pink in pork, you know it was cut within the last day or two. If it’s started to turn brown, then you know it’s been sitting in the fridge for a few days. The meat is still good if it’s brown, you just have to realize it’s just been sitting in the fridge for a few days. If you’re looking to find a deal, find meat that’s as close to the cherry red color but has a $1/$2 off sticker because you’ll be getting the freshes meat and still getting the discount.


4 Responses to “The Changing Color of Raw Beef”  

  1. 1 dennis

    Hmmm…. I wonder if any meat packing plants are filling the packages with inert gas to keep the meat from browning while on the shelf?

  2. 2 jeff

    Yes, some packing plants will use carbon monoxide to leave a lasting red color that will not give any real indication of freshness. The carbon monoxide will bind very strongly to the myoglobin and slow the oxidation process.

  3. 3 Graydon

    Based upon a local news story a good portion of the stores around here are using CO to keep that red color longer. Which ultimately highlights the need to pay attention to use/freeze by dates on meat.

    Of course in good news fashion they make it sound like it’s some atrocity to use CO and that you are liable to eat rotten meat and die.

    What would have been more informative to the public is to simply say “Hey, these guys use CO in the packaging to make it look nice longer… so DON’T use that meat that’s a week past the use by date just because it still looks good!”

    But, if you get your meat at a butcher… then definately pay attention to the color. That and don’t expect really fresh meat on Saturday afternoon just before they close.

  4. 4 gm

    Ultimately I think since people will be checking dates and not just relying on color (if it says two weeks old but still looks “fresh,” what are you going to believe?), I don’t see this C02 pumping as a really big deal… but that’s only if I know about it beforehand. Until you folks mentioned it I had no idea…

Leave a Reply


Syndicate

  • Add to Google
  • Subscribe in NewsGator Online