Kettle souring without sterilization

[drubes14]

Hi all - going to be doing a kettle soured, 100% brett brown ale in the next few weeks once I get my HERMS fully rigged up. I've been doing some reading on kettle souring to make sure I've got the hang of things.

It seems like the standard operating procedure for many is doing a quick boil once you mash to actually sterilize the wort, and the inoculating with lacto or other strain.

My gut instinct is actually to not sterilize, let the mash sit on the grain bed, and kettle sour at 90-100 degrees for 24 hours, and see what kind of bacterial expressions you might get it. I'm sure there's some diverse flora out there that could make some fascinating flavor profiles.

Wondering if folks had any feedback on kettle souring like this without actually sterilizing the wort?

 

[cactusgarrett]

So you're really mash souring, not so much kettle souring, yeah? Are you souring before you runoff and collect the wort? Plenty of people don't pre-boil, and plenty of people don't even boil after souring, as well.

I'm not a gambling man, myself, so I like to know that my effort won't be for naught by an unexpected factor ruining a batch. Most likely that's not what would happen, but I like to hedge my bets whenever possible.

 

[BrewInspector]

Kettle sours are done after the mash runnings are collected. Lacto is the most common for this. I'm not sure that Brett will be able to contribute much in only 24 hours. They are typically soured for loooong periods of time. Months are common. The quick boil is usually done after lacto souring is complete to kill everything so that souring does not continue, so the yeast has no competition and to eliminate contamination of equipment used post souring.

 

[cactusgarrett]

OP mentioned inoculating post-mash with lacto. S/he didn't explicitly state it but I took the reference to "100% brett brown ale" to mean the brett was being introduced post-souring. I believe s/he's got the process down, and difference between boil vs no-boil is the only concern.

Additionally, the puckering "sour" flavor that most people associate with sour beers (at least with kettle sours) comes from lacto or pedio over the course of months. Given time, brett contributes the earthy, funky flavors/aromas. I know I'm splitting hairs, but I just want to avoid any misconceptions.

 

[stz]

I usually sparge at 80C and as a sparge can take upwards of an hour consider that 'pasteurised' enough for kettle souring. This works fine, you are not sterilising the wort, but you are reducing bacterial counts to an insignificant level. Pre-acidification and holding high temperature alongside plenty of a known good lacto culture handle the rest and the aim is to get it done inside of 48 hours before significant off flavours develop. I then boil as usual and ferment with whatever I want. Personally I'd kettle sour (if you want a standardised sour), boil, ferment with brewers yeast and then age with brett which takes a long time to get interesting. I'd design the recipe to include plenty of unfermentables for the brett and age without sweating the effort to ditch close to all of the yeast as it'll metabolise the products of autolysis.

If you are prepared to roll dice sour mashing is a thing. Pre-acidification is accomplished with acid malt for the purists and you just hold the mash in the correct temperature range until it is done then increase the temperature to continue conversion and 'mash out' your ratio of fermentables. Great beer is made this way, but not every time! I'm sure for several success stories there is one of ditching a batch of baby vomit.

Why do I like souring off the grain? Control. It is much easier to get predictably good results. Also it is really easy for me to reduce the level of dissolved oxygen, seal the wort up and evolve co2 through it allowing it to spund, heat it etc. Trying to do all this with the entire mash is just ... a lot more effort. I'd struggle in particular to heat the mash through a range of temperatures as my system is designed as single/x infusion, fly sparge.

 

[drubes14]

cool, thanks for all the responses guys. yes, @cactusgarrett, you're correct. I'm talking about the merits of souring either in the kettle, sterilized with an inoculation, or instead in the mash with the endemic microbes on the grain husks. I am planning on using this Brett (https://bootlegbiology.com/product/funk-weapon-1/) for my actual fermentation post boil.

However, noted what you all are saying. I was thinking that maybe with the diversity of flora on grain, you might get more complex sourness/funkiness in a 48 hour window doing a kettle/mash sour than, say, sterilizing and pitching a mono-strain of lacto for that same amount of time.

I guess the only way to figure out is to experiment.

 

[Craigmn]

The problem with relying on grain is sometimes it will give you some bacteria that will make the beer cheesy/puke smelling. The name of the bacteria/acid eludes me currently. But many great beers are made either way so do what you will.