Answered by Shaykh Yusuf Weltch
Question
When grapes start to rot, are they considered najis? Secondly, if grapes are past their ‘Best before’ date by 3 or 4 days but seem fine, can they still be consumed?
Answer
In the Name of Allah, the Most Merciful and Compassionate
Grapes are Pure
Grapes are pure and cannot become impure unless they become wine. Grapes turn into wine through fermentation, which can take a very long time. [Shurunbulali, Maraqi al-Falah]
Edible
If the grapes have passed their expiry date and still appear edible, eating them is permissible and even recommended, lest one fall into wastefulness (israf).
Eating them will only be impermissible if they have reached a point where one is reasonably sure that they make fall sick by eating them. [Nahlawi, al-Durar al-Mubaha]
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani