Is this ground beef safe to eat? A few days ago I purchased a pound of ground beef from the supermarket, it was already on clearance when purchased. Since then, the beef has turned grey all throughout, and has a slight scent to it. I wouldn't say that the scent is necessarily unpleasant, but it's slightly sour, and has an almost buttery or "farm" smell to it. I can't quite explain it well. I am currently cooking the meat, and it still has that smell, and it's since permeated throughout the house. I really have no idea if it's good or not, because it certainly doesn't smell unpleasant, though it does have a smell. As well, it didn't feel slimey, or anything of the sort. The only troubles are that the smell is there, whether it's bad or not, and the entirety of the beef has turned gray with very little red left remaining inside, and mostly dispersed. I am wondering if this is safe to eat or not, or if it's perhaps best to throw it away?

Edit: Also I should note, I noticed that the blood has also turned brown, and the sell-by date was yesterday.
When in doubt, throw it out.

There are three main indicators to spoiled beef:


Texture: beef becomes slimy as it spoils.
Color: beef will go gray as it spoils, BUT, it will also go gray due to it oxidizing. This makes it a somewhat unreliable measure without the other indicators.
Smell: as beef spoils it will start to smell sour. Note that you did mention the smell being sour in your description.


Your beef has hit two out of three boxes. It may just be starting to spoil.
I would consider it potentially unsafe to eat.

But why take the risk?