Purple Meat, Steak & Beef – Why Beef Changes Color

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, gasses such oxygen, carbon dioxide, and nitrogen are 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 our sourcing 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!