Why is it that in the "good old days" (I've been cooking/ buying/butchering for 6 decades) freshly ground meat was red until prolonged oxygen exposure turned it brown (store-bought, packaged meat was a bit greyer...darker red on the outside and nice pink/ red on the inside). Today I notice the opposite, red on the outside and grey on the inside. Why is this happening?

  • I've noticed the same, but I can't remember if that's true of all of the places that I get meat from, or how it's packaged (eg, the strange puffy packs where it's a plastic container w/ a fused plastic sheet on top, vs. the old fashioned shrink-wrapped ones ... or chubs or heavier plastic like cryo-vac (the last two which would've been done at a factory rather than the local store ... and might've been done in a low-oxygen environment) )
    – Joe
    Jun 10, 2018 at 21:59
  • 4
    Likely a change to nitrite regulations. Here is Ireland: fsai.ie/faq/use_and_removal_of_nitrite.html We do it in US too. Jun 10, 2018 at 23:41
  • @WayfaringStranger : that'd affect sausages ... but to the best of my knowledge, supermarket ground beef is just ground meat and fat ... no other additives.
    – Joe
    Jun 11, 2018 at 20:12
  • @Joe My food science is from the early 80's. Things may have changed with hamburger. I was told nitrite was commonly used, but people did start complaining about it back then. Perhaps its just in processed meats now. indianapublicmedia.org/amomentofscience/… Jun 11, 2018 at 22:46
  • @Joe you'd be surprised what's put in to make it look "better" for sale, especially in the US and Canada (the EU has very strict regulations and any additives would have to be listed on the packaging, but who reads the packages of supermarket meat anyway...).
    – jwenting
    Jul 31, 2018 at 10:37

1 Answer 1


The color of meat comes from the pigment myoglobin. Freshly cut meat shows a purple-red color. When exposed to air, myoglobin forms oxymioglobin, providing an attractive cherry-red shade. However, long exposure to air and store lighting lead to the formation of metmyoglobin, which is brownish-red. The inside part of the meat can show a more greyish color due to the lack of contact with oxygen.

The industry uses some techniques to control / cover the oxidation of myoglobin up to metmyoglobin and keep a nice red shade for a longer time.

  1. Modified atmosphere packaging (MAP): to avoid complete oxidation of the meat and final brownish/greyish color (that does not look appealing anymore); some gases like carbon dioxide and nitrogen are used to decrease the content of oxygen and to slow down this process. Therefore, the outside doesn't turn grey that fast. For more information please refer to: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4093050/

  2. Color additives: in Europe, minced meat is a product category that is subject to contain color additives according to the Regulation (EC) No 1333/2008. E.g. the category "burger meat" can contain carmine or carminic acid (red color extracted from crushed bugs and stabilized with aluminium salts...), whereas other categories within the group may not be allowed to contain such color additives but natural colors or vegetable extracts. Nowadays many meat producers are switching to red beet or radish extracts to enhance the red shade of fresh minced meat in fresh sausages, meatballs, etc. while keeping "clean label". In the US there is a list of commonly used meat additives (https://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/food-labeling/additives-in-meat-and-poultry-products/additives-in-meat-and-poultry-products)

Note: nitrites and nitrates are food preservatives not used in fresh meat but in cured and/or processed meat.

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