Kettle Sour (surprise! low gravity)

[Yacov327]

So I just finished a kettle sour I started four days ago. When I started I had 7.5 gal. OG 1.044. I ended with 6 gal. OG 1.027.

My question is this: Why is my OG so low after my boil today?

If I am an idiot ,and there is an obvious answer, then I need it. This is only my second time making this kind of beer. Here was my process:

Mash 60 min 75% pale 25% white wheat
Boil 10 min
Chill to 100F
Pitch 2 Goodbelly shots in to 7.5 gal wort OG: 1.044
Kept in water bath at 95 for 3 days, pH dropped from 5.8 to 3.9 during this time
Let it go for 1 more day pH dropped to 3.8
Boil for 60 min
Chill to 80F (it's 90F here I couldn't get any cooler)
6 gal wort into fermenter OG: 1.027, pitched 2000ml starter of S-04

Let me know if you want more details.

 

[SanPancho]

two things-

one- if a yeast got in there you could have had them fermenting and eating up the sugars, which would lower your gravity. (bacteria wont really do it to any noticeable level)

two- user error. either you goofed on gravity measurement 1, or on second measurement. did you remember to cool the samples? correct for any temperature differential vs the temp on your hydrometer?

if the measurements were correct, then something got in there and started eating all the sugars.

 

[Yacov327]

two things-

one- if a yeast got in there you could have had them fermenting and eating up the sugars, which would lower your gravity. (bacteria wont really do it to any noticeable level)

two- user error. either you goofed on gravity measurement 1, or on second measurement. did you remember to cool the samples? correct for any temperature differential vs the temp on your hydrometer?

if the measurements were correct, then something got in there and started eating all the sugars.

I used the same hydrometer for both samples, cooled to around 80, and used the Beer Smith calculator to correct for temp on both samples. (I wish I had taken a reading before I started my boil today...)

I find it very reasonable that a wild yeast would have gotten in. I had the kettle submersed in a water bath with an aquarium heater to hold it at 95F.

If a wild yeast did get in and eat up all my sugars, did they also produce alcohol? I assume they would.
I also assume that I boiled off all that alcohol during my boil today?

 

[SanPancho]

its one or the other, so if you're confident in the measurements, then something ate the sugar and that most likely means yeast.

and yes, if i recall ethanol is volatile at like 150, so boiling definitely should have driven off the alcohol. basically, you've gotten yourself a pretty weak berliner. if there's no off flavors then i'd just roll with it. you'll be in the 2.5 to 3% ABV range i believe so kind of perfect for a traditional berliner.

 

[Yacov327]

its one or the other, so if you're confident in the measurements, then something ate the sugar and that most likely means yeast.

and yes, if i recall ethanol is volatile at like 150, so boiling definitely should have driven off the alcohol. basically, you've gotten yourself a pretty weak berliner. if there's no off flavors then i'd just roll with it. you'll be in the 2.5 to 3% ABV range i believe so kind of perfect for a traditional berliner.

If I didn't want that, could I boil up an appropriate amount of dextrose or DME, cool and toss it in? Seems like I ought to be able to.

 

[SanPancho]

yep

 

[Yacov327]

Resurrecting this thread rather than starting a new one. The beer in my original post turned out great after adding DME. However I have done a few sours since and they all have the same problem.

Are the wild bacteria or the lacto that are eating up my sugars producing the same amount of alcohol that sac produces? If so I'm going to just stop kettle souring and just roll with the lacto and wild yeasts to create the alcohol. Might throw in sac after the first couple days just to speed things up. Or, are the lacto/bacteria not producing the alcohol I want?

Two options I see. Start with a higher gravity beer to get the alcohol I want. Or continue adding DME after I sour the beer. I feel like the second option is the only way or really knowing how much alcohol I am producing.

 

[Amadeo38]

I’m not sure how much, but heterofermentative bacteria produce lactic acid as well as alcohol. You might want to experiment with a homofermentative strain for your kettle sours. Also, a quick sterilization of the wort (180F for a minute does the trick) before cooling to souring temp, and then pre-acidifying the wort with an acid (most use phosphoric) will prevent a lot of baddies from infecting the beer a way you didn’t want.

 

[RPh_Guy]

Resurrecting this thread rather than starting a new one. The beer in my original post turned out great after adding DME. However I have done a few sours since and they all have the same problem.

Are the wild bacteria or the lacto that are eating up my sugars producing the same amount of alcohol that sac produces? If so I'm going to just stop kettle souring and just roll with the lacto and wild yeasts to create the alcohol. Might throw in sac after the first couple days just to speed things up. Or, are the lacto/bacteria not producing the alcohol I want?

Two options I see. Start with a higher gravity beer to get the alcohol I want. Or continue adding DME after I sour the beer. I feel like the second option is the only way or really knowing how much alcohol I am producing.

Here's a better option:

Make wort as normal. Boil as normal (but use no hops). Chill as normal.
Pitch your yeast and L plantarum (e.g. GoodBelly) at the same time.
Ferment at 65°F or higher.
Optional/recommended: add hop tea or dry hops after souring completes.
Package as normal.

Easy Peasy, and drastically lower risk of contamination problems.

Cheers

 

[Amadeo38]

Here's a better option:

Make wort as normal. Boil as normal (but use no hops). Chill as normal.
Pitch your yeast and L plantarum (e.g. GoodBelly) at the same time.
Ferment at 65°F or higher.
Optional/recommended: add hop tea or dry hops after souring completes.
Package as normal.

Easy Peasy, and drastically lower risk of contamination problems.

Cheers

Note that this procedure may not kill the lacto if you do the dry hop only portion. Most lacto is sensitive to IBUs above 5, so the hop tea may be required to stop it. I’m not positive if exceeding the IBU comfort level of the lacto actually kills it like boiling does. In that case, you’ll need to take care when packaging if you’re also someone who brews clean beers. That said, it’s the bacteria I use since it’s cheap and easy (can pitch goodbelly shots or buy the straight probiotic pill and dump a few capsules worth in the wort).

 

[RPh_Guy]

Q & A

Are the wild bacteria or the lacto that are eating up my sugars producing the same amount of alcohol that sac produces?

Bacteria do not produce significant amount of alcohol.

I’m not sure how much, but heterofermentative bacteria produce lactic acid as well as alcohol.

...Even hetero species.
Almost all of the fermentation byproduct (AKA carbon utilization) from Lactic Acid Bacteria is .... lactic acid!

If so I'm going to just stop kettle souring and just roll with the lacto and wild yeasts to create the alcohol. Might throw in sac after the first couple days just to speed things up. Or, are the lacto/bacteria not producing the alcohol I want?

Wild yeast generally produce the same ethanol as domesticated brewers yeast, though wild yeast fermentation is typically undesirable because of potential off-flavors.

Note that this procedure may not kill the lacto if you do the dry hop only portion.

You are correct. Hops do not kill bacteria, rather they inhibit metabolism (they are bacteriostatic against all gram positive bacteria).

Most lacto is sensitive to IBUs above 5, so the hop tea may be required to stop it.

Both dry hops and hop tea inhibit souring. In the case of L plantarum, about half an ounce of hops per 5 gallons completely stops acid production.
Hop quantity matters more than calculated IBU with regard to prevention of souring.

take care when packaging if you’re also someone who brews clean beers.

Same as always; clean your equipment after use and no-rinse sanitize before use.

L plantarum will not sour a hopped beer even if you dump it right into the wort. There's no reason to be afraid.

Cheers

 

[Jag75]

@Yacov327 , I just did the post souring that RPH guy mentioned. My 1st sour and it worked great.

 

[shortyz]

what did the top of the wort look like after the 4 days of souring? ive been down this road a couple times with sours and if u have yeast u will see it within a day, the wort should just look like wort no garbage floating on top.

ive now switched to swansons plantarum pills, after doing this every sour has worked perfectly!