Purity: Ruling on Bubbling of Unripe Grape Juice
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 202
Unripe grape juice does not have the ruling of grape juice; it is therefore pure and lawful to drink if it bubbles. Furthermore, if it is not known whether something is an unripe grape or a ripe grape and it bubbles, then eating it is lawful.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)