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Why Beef Changes Color

by Pre Brands September 26, 2019

1 Comment

Julie, the food scientist and quality manager at Pre brands, holidng different beef packages that have different shades of pink and brown meat in them.

Do you ever wonder why our beef is purple in the package? 


It’s not so often that you see a purple colored New York strip or ribeye at the grocery store. But if you have shopped Pre® grass fed and finished beef, you’re probably familiar with the purple beef we offer. Most of the steaks and ground beef you come across in the store are red in color and psychologically, we tend to think the red color is more appealing. Keeping meat fresh is something we work hard towards and are constantly monitoring at Pre. One of the more natural ways to combat spoilage is by vacuum-sealing our products so that all the oxygen is removed. This keeps beef in it’s natural state and in turn keeps the beef fresher, longer.

The color of fresh beef is determined by myoglobin. This is a protein found in muscle tissue and is normally purple in color. It changes color depending how much oxygen it is exposed to. When exposed, the iron in the muscle starts to react and become unstable, turning either red or brown depending on the level of oxygen present. This is why beef changes color.


There are 3 main states for this color change:

STATE 1: Oxymyoglobin Atmospheric Oxygen (O2) Present (bright red in color)

STATE 2: Metmyoglobin Low Oxygen (O2) Partial Pressure (brown in color)

STATE 3: Deoxymyoglobin No Oxygen (O2) Present (purple in color)

 

 

 

 

So why does most packaged beef look red?

The color of vacuum packaged beef will be distinctly different than beef in an overwrap tray or in a MAP (Modified Atmosphere Packaging) package. Vacuum packaged beef will appear a deep red/purple color compared to the bright red color typically seen in other types of packages and behind the butcher counter. The reason for this difference in color is the presence of oxygen.
In a vacuum package, oxygen is removed from the package creating an anaerobic environment – an environment where no oxygen is present. This changes the color of the meat to that deep red/purple color. This is called “Deoxymyoglobin”.


In an overwrap tray, oxygen is present due to the open nature of the package with the surrounding air we breathe. In MAP packaging, 70% oxygen and 30% carbon dioxide gas is added in order to keep a bright red color. This is called “Oxymyoglobin”.

When Pre’s vacuum-sealed package is opened, and the beef is brought back into the presence of oxygen, you will find our Pre beef changes to a bright red color. Our beef is a deep purple color in the package. This is because all the oxygen has been removed to preserve freshness. When you open up the package, it is exposed to oxygen and turns bright red – that’s what we call blooming. Because we seal our meat airtight, you get to see this beautiful transformation.

You will also notice this phenomenon behind the butcher counter or in the trays, when some steaks overlap. The overlapping steak will leave a brown color because it was limiting the oxygen exposure to the meat. That state is called “metmyoglobin” as referred to in the visual below.

The presence of oxygen will gradually deteriorate meat and oxidize fat. In MAP packaging(Modified Atmosphere Packaging) additional gasses are added to prolong freshness. With Pre,® we do not add any gasses to help extend freshness, we just remove as much air as possible. 

 

 

The Pre® Difference

In summary, we know the bright red color of beef is unstable and the presence of oxygen will gradually deteriorate the meat and oxidize fat. (This is why beef does not last as long when it is behind the counter or in those overwrap trays.)  In MAP packaging, this shelf life issue is combatted with adding additional gasses such as Nitrogen and Carbon Dioxide but the total shelf life is much shorter than Pre because eventually the presence of oxygen will start to spoil the meat. With Pre packaging, we do not add any gasses to help extend the life of beef, we just remove as much air as possible. Upon removing the oxygen, the beef is back to a stable color and freshness is extended.

We tested out our steak packaging in a 5-day fridge test alongside a butcher paper wrapped steak. See the test results here.
Learn more about oursourcing and expiration dates and if you don’t see Pre in your local grocery store,please download this form and give it to the meat manager so that we can be near you soon!

1 Response

Sophia
Sophia

September 30, 2019

Thank you for this very important information on why beef has these different colors.

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