Green garlic soaked in vinegar is a common condition that many people encounter. When we see green garlic, we worry about whether we can still eat it or not. The reason is because vinegar is acidic. When used to soak garlic, it will react with the amino acids in garlic and create carbon-nitrogen rings called pyrroles.
When pyrroles combine together, they form polypyrroles and form colors. If 4 pyrroles combine, it will form green, and if 3 pyrroles combine, it will form blue.
Therefore, if after a period of soaking the garlic in vinegar it turns green or blue, this is considered normal and safe, the appearance of the color does not affect the taste of the garlic.