It’s one of my most commonly-asked questions.
What is the deal with
that blood or water in my package of meat?
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| Beef steaks and purge Photo courtesy Macc Rigdon |
When you take your tasty cut of meat out of the package,
there is a pinkish liquid that is left behind. Most of the time, there is even
a little soaker pad in the package to soak it up.
What is that stuff?
Short answer:
It’s a combination of water, lactic acid, and meat pigments
that seeped out of the meat.
Longer answer:
In science class, we all learned that our bodies are largely
made up of water. The same is true for animals, and a high percentage of that
water is held in the muscles and stays in the muscle when it’s converted to
meat.
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| Soaker pad in a chicken tray |
Water in the meat is what creates the juiciness we experience
when we eat a juicy steak, a tender ham, or a succulent turkey
(#tokenthanksgivingreference). Water helps give meat the texture and flavor we
expect. Meat without water is jerky, dry and tough.
Think of the proteins in meat as a sponge. As the meat ages
and the more it is handled (cut, shipped, packaged, etc.), the protein sponge
loses its ability to hold onto water. So, the water seeps out of the meat over time.
When the water seeps out, the protein that gives meat its
color (myoglobin) flows out with the water. That protein gives the purge its
color. Although it’s similar to the protein that gives blood its color
(hemoglobin), it is not blood.
The ability of the meat to hang on the water is dependent on
several different things, including the species and age of the animal, the
fatness and grade of the meat, the length of time since the animal was
harvested, which muscle the cut of meat was from, and how the meat has been
handled and processed. Meat scientists spend hours and hours trying to figure
out purge and what causes it.
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| Pork chops in a purge loss study Meat scientists have lots of creative ways to measure purge Photo courtesy Macc Rigdon |
Sometimes meat processors will add a solution to meat cuts
to make them more tender, flavorful and juicy. That solution can change the
amount of purge in a package, but the presence of purge does not automatically
mean that water or anything has been added to the meat. Most of the time, purge
is just a natural result of water leaving the muscle.
Some of the water in meat will evaporate out when it’s
cooked. That’s why cooked meat is lighter in weight than raw. As the meat is
cooked, the myoglobin will denature and lose its red color. So the juice that
runs out of a rare steak may still be pink or red, but the juice from a cooked
steak is colorless.
So, the water in meat packages is just purge, water and a little myoglobin. Maybe we should give it a
better name.
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| Vacuum packaged pork with purge Photo courtesy Macc Rigdon |
Something I learned from writing this blog: When you ask
your meat-scientist friends to send you pictures of purge, be prepared to get a
whole lot of them! I wasn’t pleased with my own photos, and a whole community
of meat scientists responded when I sent out a request for pictures on
facebook. Thanks, friends!
