Do we need to check if supermarkets performed bi'ur on shemitah wine?
Question
I see that supermarkets still sell Golan Heights shemitah wine and that otzarot beit din continue selling and distributing holy wines and grape juice now, after bi'ur time (Pesach 5783). Do I have to find out if the stores/distributors properly performed bi'ur before buying the wine?
Answer
While there is a minority opinion that otzar beit din needs to perform bi'ur on wine and grape products, this is not the mainstream ruling.
Bi'ur is required for privately owned produce; we are not supposed to stock-pile it and thus prevent access to others. However, wine and grape juice distributed by otzar beit din (even through supermarkets) does not belong to private individuals and thus is exempt from bi'ur.
In Israel
The supermarkets and distributors at stations throughout Israel are all considered otzar beit din agents. This applies in Israel only.
Outside of Israel
Outside of Israel only exporters are otzar beit din agents, while privately owned-stores are not.
Unless you can verify that bi'ur was performed on holy wine (Golan Heights), avoid buying such wine until after Shavuot. By then, the vast majority of wine will have been exported after bi'ur time.