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  • It's kind of unavoidable if you cut into a big juicy rare steak

  • You're gonna get some juice. Watery, red liquid seeps out of the meat and on to the plate and it kind of looks like blood.

  • But I have good news for people

  • who like to eat red meat but don't like to eat blood

  • It's not blood.

  • It's just water plus a handy protein called myoglobin.

  • All meat is muscle but the muscle looks different

  • depending on what it's used for

  • White meats like turkey and chicken come from muscles

  • that are used in short spurts every so often

  • but have to get moving quickly

  • Think of the chicken breasts

  • They don't actually use their wings very often

  • Red meats like beef, lamb and even pork come from muscles used for long strenuous activities

  • like carrying a huge cow around all the time

  • Before cooking,

  • these meats are a pinky, reddish color.

  • Holding up a heavy cow is some serious work.

  • Work that requires a lot of oxygen for fuel

  • which is where myoglobin comes in

  • Myoglobin is a special protein

  • with an iron atom at its center,

  • which bonds with, then stores and delivers oxygen to muscle cells

  • It works together with hemoglobin, another oxygen carrier

  • to get oxygen to the cells that needed.

  • The difference between red meat and white meat

  • comes from the levels of myoglobin in the muscle.

  • And myoglobin protein itself is red

  • so the more myoglobin in the cells the redder the meat appears.

  • And that juice that's spilling out of your meat?

  • That's a combination of water and myoglobin.

  • The animal's blood was removed when the meat was processed.

  • Beef is around 0.8% myoglobin and lamb has a little less at 0.6%.

  • And all of those ads have been lying to you

  • because at 0.2% myoglobin

  • pork is generally considered red meat too.

  • Chicken only has about a quarter of that amount

  • But what about humans?

  • Well, our flesh is about as red as red meat can get

  • at 2% myoglobin.

  • If you have been like steak

  • but you don't want red juice

  • you have options.

  • Myoglobin is red when it's bonded with oxygen.

  • When meat is cooked rare,

  • up to about 60 degrees Celsius,

  • the color stays

  • Above that temperature,

  • the iron atom in myoglobin loses an electron,

  • and therefore its ability to bind with oxygen.

  • Instead, the myoglobin forms a new molecule

  • called hemichrome

  • that gives medium and well done meet its brown gray color

  • Myoglobin will also turn brown

  • if it's exposed to air for long enough,

  • because that makes the iron atoms lose an electron too.

  • Which is why checking the color

  • can be a handy way to tell

  • if your store-bought meat is still fresh

  • It doesn't always work though,

  • because some meat producers add compounds

  • that keep the meat red and the color can last way past the expiration date.

  • But if you do end up buying that red meat and cooking it rare,

  • I hope you enjoy your oxygen rich protein water.

  • Thanks for asking and thanks especially to all of our patrons on Patreon who keep these answers coming

  • If you'd like to submit questions to be answered,

  • or get these quick questions a few days before everyone else

  • go to patreon.com/scishow.

  • And don't forget to go to youtube.com/scishow and subscribe.

It's kind of unavoidable if you cut into a big juicy rare steak

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B1 US myoglobin meat red meat oxygen protein muscle

Why is Red Meat ... Red?

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    Ruby Lu posted on 2016/02/08
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