[troybinso]

I have been fooling around with souring with lactobacillus as the primary fermenter in the carboy, then adding fruit and yeast to finish the fermentation. This time I want to try sour worting in the kettle then boiling, chilling and adding fruit and yeast.

My question is regarding the lacto that I have. It seems to be heterofermentative (it creates lactic acid as well as alcohol and co2) since it has about 60% attentuation rate. If I use this in the kettle and boil for 15 minutes, will I be driving off all of the alcohol that was produced by the lactobacillus in the first place?

[erockrph]

Looks like you should expect to have roughly 40% of your alcohol remaining after 15 minutes per the chart on this page:

http://whatscookingamerica.net/Q-A/AlcoholCooking.htm

[troybinso]

Huh. Interesting chart. I kind of assumed that alcohol was more or less immediately boiled off.

I did a little more reading about lactobacilus on milk the funk at it seems like even heterofermentative bacteria should only produce a very small amount of alcohol, indicating my sample has been contaminated with some sort of yeast. Hopefully the new pitch I got is ok.

[S. cerevisiae]

Wort does not need to be boiled to kill vegetative cells.  Vegetative bacteria cells start to die off at 140F.  Ethanol does not boil below 173F at normal atmospheric pressure.  One strategy would be to boil the wort, and allow it to cool to between around 100F and 110F before inoculating it with Lactobacillus.  The temperature of the wort should be held at approximately 95F (35C) until it is sufficiently sour before raising the temperature to 160F.   The Lactobacillus cells will be dead by the time the wort hits 160F.

[troybinso]

Wort does not need to be boiled to kill vegetative cells.  Vegetative bacteria cells start to die off at 140F.  Ethanol does not boil below 173F at normal atmospheric pressure.  One strategy would be to boil the wort, and allow it to cool to between around 100F and 110F before inoculating it with Lactobacillus.  The temperature of the wort should be held at approximately 95F (35C) until it is sufficiently sour before raising the temperature to 160F.   The Lactobacillus cells will be dead by the time the wort hits 160F.

Great thanks. I hadn't considered only getting it up to 160F.

[brewinhard]

If you are just pre-souring in the kettle with lactobacillus, you probably won't observe much of a drop in the OG prior to boiling it.  Are you pitching yeast after the kettle boiling and chilling to finish the fermentation off?

[duboman]

If you are just pre-souring in the kettle with lactobacillus, you probably won't observe much of a drop in the OG prior to boiling it.  Are you pitching yeast after the kettle boiling and chilling to finish the fermentation off?

Agreed, I kettle sour my Gose with lacto, a few days at 90oF and I lose .01-.02 in OG

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[troybinso]

How long do you boil for? Any DMS worries?

[duboman]

After kettle souring when you get to your desired pH simply continue your process with a traditional boil, add your hops as scheduled and finish your wort as normal. Easy peasy:)

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[reverseapachemaster]

How do you know you have a pure lacto pitch? You could easily have yeast mixed in with your lacto. Unfortunately putting lacto pitches from most of the labs under the microscope exposes the presence of sacc and other yeast strains.

[klickitat jim]

How do you know you have a pure lacto pitch? You could easily have yeast mixed in with your lacto. Unfortunately putting lacto pitches from most of the labs under the microscope exposes the presence of sacc and other yeast strains.

I used to think BS, they should be pure, until I studied up on banking techniques and found that you have to plate smack pack samples for singles before slanting... so why wouldnt you need to with bugs? That and I almost always get a 5-15pt drop in SG from pitching lacto to primary from a smack pack, and Wyeast says in theory it shouldn't drop much at all. In a yeast smack pack you wont notice if your 1056 has .1% 1728, but .1% 1056 in a lacto pitch would show up by gravity dropping after it grew enough. My lacto runs a week at 98-100F which is long enough for a tiny amount of sac to grow up and eat some sugar.

Having said that, I just ignore it and keep on trucking.

[brewinhard]

How long do you boil for? Any DMS worries?

I have done no-boil beers with zero DMS issues even with 60% pilsner malt.

[troybinso]

How long do you boil for? Any DMS worries?

I have done no-boil beers with zero DMS issues even with 60% pilsner malt.

From what I understand, the DMS starts to form as you raise the temperature of the wort, and then is boiled off during a rigorous boil. So I guess I am worried about a short, 15 minute boil, or just raising the temperature to pasteurization temps and creating some DMS, but not boiling it off.

[duboman]

If you are kettle souring, once your wort reaches the desired pH or sourness you then proceed to the traditional boiling of the wort so dms production isn't an issue

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[brewinhard]

+1.  You would perform a typical 60 or 90 minute boil based on your preference and grain bill.