Originally Posted by mrphillips
Is this crazy idea of his going to work? God I hop it does.
Yes, and maybe no.
Many of those organisms are lactic acid bacteria, which is what he wants. Unfortunatly most lactic acid bacteria (not all), are adverse to hops; that is, if there are hops present, they will remain dormant. Some can't tolerate any hops, some are ok to about 10 IBUs, anything more, and it is a rare strain that will survive.
The way to do it, is to add the bacteria before doing the boil and adding the hops. If you only want it slightly sour (ala guiness), you can just sour a small amount and add that to the main batch when soured enough.
Also, 90 F is low. I usually go for 100F and have found it takes from 5 to 7 days to decently sour.
I usually do not boil after souring, unless I want to add hops. The alcohol (and low PH) will sort out any bacteria. I usually do this for Berliners which don't have any hops. Some of this bacteria creates alcohol with the lactic acid, and by boiling it, you will be driving off the alcohol, and ending up with a low alcohol beer. To tell what you have, check the gravity after souring. If you have homofermentive bacteria, the gravity will be similar to the starting gravity. If you have heterfermentive bacteria, you will see a significant reduction in gravity.
He may get lucky, but I suspect nothing will happen. It all depends on what bacteria he has in there.