There are differing rulings regarding wine vinegar among various Islamic schools of thought. According to Ibn Rushd, it is known that the jurists have reached a consensus that it is permissible to consume wine that has naturally turned into vinegar. However, there are differing opinions on wine that has been intentionally transformed into vinegar by human intervention.
Some jurists, such as those from the Hanafi school and Imam Malik, consider the transformation of wine into vinegar through human intervention to be halal, while the Shafi’i and Hanbali schools do not allow such interventions. These differing views stem from interpretations of whether the intoxicating property of wine is lost during the process of becoming vinegar and whether this change nullifies its prohibition.
The Shafi’i school generally views any intervention with wine as haram. For example, they state that vinegar made by adding substances like bread, vinegar, or onions to wine is haram, as these substances are considered impure when mixed with wine, and this state continues after fermentation.
On the other hand, the Hanafi school likens the process of wine becoming vinegar to the tanning of leather. When the intoxicating properties of wine are lost, its prohibition is also lifted, and the resulting vinegar is deemed halal. In this case, the view that vinegar made from wine is halal is the preferred opinion in the Hanafi school.