25 May 2020

"Beef rainbows" explained


I eat beef, and see these frequently.  Never thought much about them until I encountered an Atlantic article that explains how they are formed:
There's enough speculation over the integrity of rainbow beef that the USDA's website has a section on "Iridescent Color of Roast Beef" near similar topics like "What does 'natural?' mean" and "what is beef?" According to the USDA, "When light hits a slice of meat, it splits into colors like a rainbow." This is something called a "diffraction grating," essentially what happens when light waves bend or spread around a surface and create a pattern. It's the same thing that happens to make rainbows on the surface of a DVD. It's understandable that folks mistake diffracted light as a sign of spoilage...
Reposted from 2013 to add this photo of a white-lipped python -


- as another example or iridescence in the natural world.

9 comments:

  1. DeformutilationMarch 2, 2013 at 5:08 PM

    Thanks for this! When I was a kid I used to think it meant the meat was bad :)

    ReplyDelete
  2. Nancy ReyesMarch 2, 2013 at 8:45 PM

    thanks. Linked to my blog.

    ReplyDelete
    Replies
    1. MinnesotastanMarch 2, 2013 at 9:39 PM

      I know. I keep a folder of bookmarks to readers' blogs and explore from time to time.

      Delete
  3. AnonymousMarch 3, 2013 at 8:57 AM

    You mean that all those fish I threw back were normal?

    ReplyDelete
  4. AnonymousMarch 3, 2013 at 8:09 PM

    We used to call that "ham-sheen," because ham was the usual host in my mother's refrigerator. My sister-in-law bought an iridescent coat in the 1980's that was exactly that color, so we called it her "ham-sheen" coat. It's kind of beautiful in a way, I guess.

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  5. steveMarch 4, 2013 at 9:51 AM

    fantastic, I tried to look up an answer for this a few months ago and couldn't find any trustworthy answers. A lot of people seemed to think it was oil from the cutting machinery (but food safe).

    ReplyDelete
  6. bkoffordMay 26, 2020 at 9:04 AM

    The link in the Atlantic article to the USDA website appears to be bad. Here is the correct one:
    https://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/meat-preparation/beef-from-farm-to-table/ct_index/#15

    ReplyDelete
    Replies
    1. MinnesotastanMay 26, 2020 at 10:06 AM

      Thank you bkofford. These old posts often have sources that have undergone linkrot. I didn't take time to correct that one. Appreciate your help.

      Delete
  7. AnonymousMay 26, 2020 at 10:13 PM

    Rainbow beef is leprauchan food. Haha.

    ReplyDelete