Spoiled garlic forms brown spots on the cloves and turns from the usual white to a more yellow or brown color. Another thing is the green roots forming in the center of the clove. These are new sprouts forming. Though not harmful these roots taste extremely bitter and should be removed before cooking.

Is it bad to eat old garlic?

Obviously, you don't want to eat moldy or mushy garlic, but sprouts cloves or even those that have browned or yellowed spots can still be used. Their taste might be slightly off, but removing the green sprout or trimming browned spots will make older cloves usable and keep them out of the trash.

Can you get sick from old garlic?

Eating garlic that has gone bad might not agree with your stomach, but there's a bigger risk with this unassuming bulb that you need to be aware of. You may be surprised to learn that consuming garlic that has been stored in oil can cause botulism, a kind of food poisoning.