Originally Posted by pdxal
You mean flush it with CO2? Oxygen is what allows pediococcus to ferment a sour mash greater than lactobacillus and cause the rotten smell of butyric acid.
I've done many a sour mash, and just covered the pot or put plastic wrap n the surface to make an anaerobic environment with good results.
Really no skill involved, just some wort, handful of raw grain, and a little time with a warm temperature...
Sorry, you're right, CO2. Before I had the ability to flush with CO2 I had a few berliners come out fine and then one that was pure baby diaper. Nothing changed in my process between the first two and the third one, which was to transfer to the boil kettle, add the grain, and let it sit at around 100f for a few days until I was happy with the level of tartness. It made me a little uncomfortable brewing them until I started kegging. Haven't had that problem since.