Fresh ground beef goes through a number of color changes during its shelf life. These changes are normal and the ground beef remains perfectly wholesome and safe to eat. When exposed to oxygen, the color of beef will turn to a bright red. This explains why the raw beef appears red on the surface and can look darker inside.
Beef can be safely frozen for 12-15 months
Pork can be safely frozen for 6-9 months
Chicken can be safely frozen for 6-9 months
If you hold meat frozen longer, it will not be harmful however the quality and flavor may diminish.
For beef, one of your best crock pot roasts would be the chuck roast and for pork the pork shoulder roast has the most flavor while a pork sirloin roast is a good leaner choice.