Sour/funk beer question

[matt77]

Hi all.
I did an all grain several weeks ago. Day after, grain left in the mash smelt pretty funky. Could i do a second mash/sparge and use this as the base to make a sour?
I've looked at a few guinness clone recipes and they take a litre or 2 before boil. Leave it for a couple days to sour (basically what i was smelling from the spent grain) then add back into fermenter after heating (71°c for 15 minutes).

A sour dough in baking is basically just this. (Using the wild yeast in the flour (from on the outside of the grains))

 

[chookherder]

You could do this with the spent grain, but it will not have a lot of sugars left to extract and you will get a lot of the tannins resulting in a bitter watery sour-beer.

I do a lot of Kettle-souring where you would do your usual Mash schedule (maybe with a short 10min boil) then cool to 37c and add some Lactobacillus bacteria. You could use your old Spent Grain here as a source of lacto, I use IBS Capsules from the chemist. The holding it at 37c for a day or two as the souring occurs, this is the ideal temp for lacto. Once it is sour enough for your liking then raise the temp to boil as you would normally, killing the lacto and sterilising the mash tun, after which you go to your normal fermentation schedule.

I believe the guinness clone recipe you are referring to are heating the 2l of sour wort to 71c before putting into the fermentor (to kill the lacto), as putting live lacto into the fermentor will be hard to remove after and could make all future beers sour. I would take it to a boil to be sure everything is dead, as you may have many different bacteria in there not just lacto.

Kettle-souring is awesome because it's fast, but the flavour profile is not as complex as you can get with a true wild ferment.

BTW my local chemist thinks I'm dying from some major bowel issue with all the capsules i buy!

 

[matt77]

Beautiful thank you. Yeah understand there won't be much sugar left but thought i could use a cheap extract tin or ldme to get things back up to taste