intentionally infecting a ferment

[Beerswimmer]

In sour beer brewing you make the wort, then cool to 120F or so, then add yogurt or lacto and cover at the surface with saranwrap for a day or 2. When it's to the sourness you desire, you heat it back up to sterilize and cool back to pitching temp and add yeast.

Or, you let the beer ferment completely, then add lacto, brett, pedio, etc. and let it get to terminal gravity. The "bugs" eat what yeast can't. Even non sugars.

I have done many, many variations of the latter using brett. Not too much experience with lacto except for the first method a few times for Berlinerweisse using a handful of grains tossed into the wort.

[engunear]

Thats interesting! Thanks.

[masonsjax]

If you brought all your grain (not just rye) to 85c for a bit, you'd avoid any unintended infection. Grain has a lot of bacteria on it and you really don't know what you're gonna end up with if you don't take steps to control it.

[MDH]

In Scotland they just distill the mash before it gets too sour. They never raise the mash to the point of killing the bacteria.

[engunear]

Yeah, thats right. I do this with rye, else I get a slimy ferment that sticks, both at high potential alcohol (3-4%) and to the boiler. It can only be stripped with steam injection.

The theory, clearly stated by Bryan Davis and also in these pages, is that adding a bacteria takes control of the situation. I guess its a matter of degree. Lactic acid is good in whiskey as ethyl lactate has a buttery taste, and lactic acid azeotropes and comes over the still in remarkable quantities considering its boiling point (151C). But you can taste in clearly in the distillate, particularly the late tails when stripping.

Some people, including some commercial distilleries, leave the mash overnight before pitching to bring up their bacteria count.

I was surprised at this batch, as I've never had off smells before, and put the reason down to the youghurt. But the two recipes are very close, and the difference dramatic. Probably when it ages the skunky one will be better, and I'll regret that some went down the sink. That would be sods law.

A final bit of amusing complication, I read somewhere that yeasts (and presumably bacteria) can be antibiotic to each other. Its a complicated game we play.