Some natural winemakers will add a small amount of sulphur at bottling in order to assist with stability and minimize the chance of the wine starting to referment in bottle

Ok, this is amazing. I hadn't ever considered this, but it's obvious, the fruit will keep fermenting while it's inside unless there's something to stop it. I would've thought it was the lack of oxygen, but using sulphur sounds like a cool strategy. I wonder whether this was discovered before modern chemistry or whether this could be done in the Middle Ages.