When glycin turns dark brown, it loses it's effectiveness as a development agent. It will stain paper and suppress highlights. Because of its cost, it is important to buy only what you will use in about 2 months.
Exactly what Denise said, it will develop but won't have the sparkle. It is the glycin (I use glycin in two other formulas and go through about 4 pounds a year) but it and the packaged 130 will keep very well in the freeze, my glycin stays almost white in the freezer. The stock doesn't like oxygen...Evan Clarke