Trying to get my head around souring techniques

I've been reading up on how different souring techniques work lately and I think I'm still confused about a few things that I hope you can help me clear up.

Kettle souring/sour mashing seem very straightforward to me; lowering the pH before the boil gets you to your desired tartness, killing critters with the boil, and pitching sacc/brett into sour (but clean) wort. The key to dropping the pH seems to be maintaining a temperature range so that the lactobacillus from the raw grains/bottle dregs/lacto culture effectively produces lactic acid.

I've also seen many instances of brewers pitching lacto cultures post-boil. Here the advice from homebrewers seems to be one or both of the following: a) pitch sacc and lacto together, but at a higher ratio of lacto to sacc, and/or b) pitch the lacto ahead of time, wait for the pH to drop, and then pitch the sacc. For what it's worth, in his book American Sour Beers, Michael Tonsmeire advocates simply pitching lacto/sacc/brett simultaneously.

With that, there are a few things that are not getting through to me:

1. When pitching the lacto before the sacc/brett, whether pre or post-boil, is the goal simply to hit an ideal pH?
2. What is the difference between pitching a higher ratio of lacto:sacc simultaneously and pitching the lacto ahead of time?
3. Where does acidulated malt come into play? Is that just a simple way of making sour beers without the hassle of the methods I outlined, or is it used in conjunction with those methods?
4. I mentioned maintaining a temperature range with kettle souring/sour mashing; is that to give your critters an advantage over whatever else is living in there? Is it just a quick way of producing lactic acid?
5. Other than sanitation/contamination concerns, is there a reason to choose to sour the wort pre-boil versus having the lactobacillus do its thing in the fermenter?

Please let me know if I misstated anything or any of those questions are unclear. I'm hoping reconciling some of these concepts will go a long way in understanding just how those critters do their thing, I'm really looking forward to hearing people's thoughts on this.

1. Yes, lacto is merely used to sour the beer. sacc is to ferment the sugars and Brett is for funk.

2. Pitching lacto and sacc together is easy, but it's imprecise. Works if you want only mild sourness and are willing to roll the dice. Once pitched, you can't control how sour it'll be, as your sacc yeast may outcompete to varying extents the lacto.

3. Acid malt isn't used in sour beers any more than in non-sour beer. It's just for reducing mash pH a couple tenths. Lactic acid (88%) is your friend -- it's used to adjust starter and wort pH down to protect a little while you wait for the lacto to kick n.

4. Yes, lacto likes warm temps.

5. Souring pre-boil is favored by folks who don't plan to use Brett and don't want bugs in their kegs and lines.

Thanks, that clears things up.

SpeedYellow said:

Souring pre-boil is favored by folks who don't plan to use Brett

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How's that? Is the Brett just cleaning up after the lacto bugs?

FoxFeud said:

Thanks, that clears things up.

How's that? Is the Brett just cleaning up after the lacto bugs?

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No, it's a matter of getting brett and lacto in your beer lines. For those who want to avoid Brett and lacto in their beer lines, they would boil after the lacto souring to kill the lacto, then avoid brett afterwards.

So the decision to lacto sour pre- or post-boil depends on if you want to kill the lacto or don't care. And again, there's the issue of control (you can easily control the souring when done pre-boil).

Ah I just read that wrong, thanks for clarifying.