Poisoned Wine

Source

I got this problem from Rustan Leino, who got it from Vladislav Shcherbina.

I solved it and wrote up my solution.

Problem    

You have 240 barrels of wine, one of which has been poisoned. After drinking the poisoned wine, one dies within 24 hours. You have 5 pigs whom you're willing to sacrifice to determine which barrel contains the poisoned wine. How do you achieve this in 48 hours?

Solution     Reveal