When to sour?

[Drewed]

As I wander down the path of sours, I find that there seems to be three distinct paths to take. There is the “Sour In The Kettle” path where a sour mash is made before the boil and hop additions. There is the “Pitch It All At Once” where the lacto is pitched at the same time as the yeast. Sub set of this would be pitch only lacto. And then the third group of “Pitch yeast, Let Ferment, Then toss in the sour bugs.”
The middle seems the easiest, but I also believe in the “Easy is often not best.”
Pros and cons of each?

 

[stz]

I love kettle souring with lacto up front because it is a fast, clean and controllable way to sour. My colleague is not keen because he prefers the interesting flavours which come from true mixed cultures, barrel ageing and time. I see all that as something very separate from just souring with lacto even though that is sort of part of it. It very much depends what you are trying to do.

It is a fact that LAB work best at higher temperatures in the absence of yeast, alcohol and hops. If you are aiming to sour at the end at fermentation or storage temperatures you must be prepared for it to take a very long time if at all with just a LAB culture and accept that significant acetic character alongside oxygen ingress is sort of required and it might be really unreliable and blending is required to produce a drinkable beer.

I think it is worthwhile though not essential to get proficient at simple kettle souring with a proven culture before just going at it and hoping for the best. The skills developed and any equipment shortfalls identified will be useful at other points too.

 

[cactusgarrett]

I'm with stz on this one. It totally depends on what you're trying to get. Kettle souring is great - fast and reliable (if done properly). With it, though, you're only getting the lactic sourness and less complexity. You don't get the funk that comes along with pitching a blend for long-term aging with brett or pedio.

In my opinion the discussion of bugs/brett with vs after primary fermentation is the real debate, since kettle souring is a different animal altogether.

 

[RPh_Guy]

Good replies here already but I'll chime in.

We have two very different microbes for souring: Lactobacillus spp. (Lacto) and Pediococcus spp. (Pedio). Both may be referred to as LAB (Lactic Acid Bacteria).

Lacto works very quickly to make a clean sour. Does not tolerate hops well during souring but you can sterilize and add hops after souring if desired. Either wild bacteria (e.g. sour mash) or lab cultures can be used. Using a sour mash technique and/or wild bacteria may produce added flavors (some of which may not be desirable). Any yeast can be used post-souring.
-Fast turn-around (a couple days beyond any regular "clean" beer)
-Predictable result from lab cultures
-No risk to equipment if sterilized
-No "funk" ... Unless you want to add Brett of course and give additional time. No one is stopping you.

Pedio takes much longer and must be used in combination with Brettanomyces spp. (Brett). Pedio is hop-tolerant. Brett takes a long time, dries out the beer, and add any number of a large potential variety of flavors a.k.a. "funk". Potential to be much more sour. Wild microbes, dregs, lab cultures, anything is fair game. Plenty of time to impart oak if desired.
-Produces more interesting beer that is unparalleled in potential flavor complexity
-Less predictable, depending on technique and source of microbes.
-Takes longer to ferment (6-24 months)
-Potential for contaminating clean beers used with the same cold-side equipment.

As far as technique...
Neither of these approaches are necessarily easier than the other.
Brett is slow to start, so whether you pitch it with Sacc or later, it won't make a huge difference in the long run.
Pitching Pedio earlier rather than later might be beneficial for making it more sour.
Depending on the species, strain, temperature, and amount of hops, giving Lacto a head start in a mixed fermentation should generally produce a more sour beer.

It's worth mentioning that we also have the option to do a 100% Brett fermentation on a Lacto kettle sour. This should be a relatively fast turn around sour (Brett doesn't fully attenuate when used alone) with a limited amount of Brett flavor from whatever species/strain was used (YMMV), similar to different Saccharomyces cerevisiae strains.
If you just love funk you CAN also use Brett for less sour or non-sour beers, something like an oud bruin for example or a pumpkin ale.
I can think of some other experimental techniques that might produce interesting results as well... Definitely have some room for experimentation.

Hope this helps clear things up. Cheers!