Does Color Change Mean the Product is Spoiled?

Aug 10, 2018

Change in color alone does not mean the product is spoiled. Color changes are normal for fresh product. With spoilage there can be a change in color—often a fading or darkening. In addition to the color change, the meat or poultry will have an off odor, be sticky or tacky to the touch, or it may be slimy. If meat has developed these characteristics, it should not be used.

Optimum surface color of fresh meat (i.e., cherry-red for beef; dark cherry-red for lamb; grayish-pink for pork; and pale pink for veal) is highly unstable and short-lived. When meat is fresh and protected from contact with air (such as in vacuum packages), it has the purple-red color that comes from myoglobin, one of the two key pigments responsible for the color of meat. When exposed to air, myoglobin forms the pigment, oxymyoglobin, which gives meat a pleasingly cherry-red color. The use of a plastic wrap that allows oxygen to pass through it helps ensure that the cut meats will retain this bright red color. However, exposure to store lighting as well as the continued contact of myoglobin and oxymyoglobin with oxygen leads to the formation of metmyoglobin, a pigment that turns meat brownish-red. This color change alone does not mean the product is spoiled.

Beyond color change, there are ways you can tell if your meat is spoiled. Spoilage is a process that occurs over time and is the result of the growth of spoilage bacteria. There is no one point in time where a product is fresh and wholesome and then suddenly becomes spoiled.  Changes in color can be an indicator that the process is beginning, but color change alone does not mean the product is spoiled. The most potent indicator of spoilage is an off odor.  A spoiled product also can be sticky or tacky to the touch, or it may be slimy. If meat has developed these characteristics, it should be discarded. A use-by date on a package can also be a good guideline.  

Some meat may also show an iridescent sheen. This is because meat contains iron, fat, and other compounds. When light shines on a slice of meat, it splits into colors like a rainbow. There are various pigments in meat compounds that can give it an iridescent or greenish cast when exposed to heat and processing. Wrapping the meat in airtight packages and storing it away from light will help prevent this situation. Iridescence does not signal decreased quality or safety.

USDA generally recommends the following:

  • Raw ground meats, all poultry, seafood, and variety meats: can be refrigerated 1 to 2 days.
  • Raw roasts, steaks, and chops (beef, veal, lamb, and pork) can be refrigerated for 3 to 5 days.
  • Cooked meat, poultry, and seafood can be stored in the refrigerator 3 to 4 days.

Find our more from Dr. Brad Kim, Meat Scientists from Purdue University.

 

Source:

The Color of Meat and Poultry. USDA Food Safety and Inspection Service (FSIS). 2015. Available from: http://www.fsis.usda.gov/wps/wcm/connect/e8dad81f-f7fc-4574-893e-bae20cf8b215/Color_of_Meat_and_Poultry.pdf?MOD=AJPERES.

Video Podcasts and Webinars

  • Grass or grain? Is there a definitively sustainable beef production system?

    03/22/2016

    The webinar examined the science relating to grass-fed and grain-fed beef in terms of sustainable... read more »

  • 2015-2020 Dietary Guidelines for Americans Update

    01/12/2016

    Kris Sollid, Registered Dietitian with the International Food Information Council and Sarah Romo... read more »

  • Meat in the Diet

    08/10/2015

    read more »

Social Media