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Last weekend I collected about 7 liters of backset from a Whiskey stripping run. It sat in a casserole for a couple of days before I got around to transfer it to a carboy and put it in the cooler. I noticed little floaters on the surface, so I reckoned Lactobacillus managed to slip in under the lid.

However, I wasnt planning on boiling the backset but adding it cold to the next batch, either during mashing or before fermentation. As a brewer I am a bit overly concerned about yeast competition in my brewery. Do I dare using the ”infected” backset in the ferment? It has no bad smell and there hasnt been any growth since I put the backset in the cooler, as far as I could see. I should be safe right?

Picture (of poor quality) of the floaters inside the carboy below.

Curious as to why using it cold rather than adding it too the gain when you gelatinize to lower the ph?

Lacto is not fast to I think if you have a good yeast pitch they will out compete and you will be done fermenting before the lacto gets to far. And it might add some nice esters you like. I have had lacto set in for a week or two before I got the stripping run and I can't say I could tell if it added esters but it certainly has not added a bad flavor.

subbrew wrote: ↑Fri Apr 11, 2025 10:25 am Curious as to why using it cold rather than adding it too the gain when you gelatinize to lower the ph?

Lacto is not fast to I think if you have a good yeast pitch they will out compete and you will be done fermenting before the lacto gets to far. And it might add some nice esters you like. I have had lacto set in for a week or two before I got the stripping run and I can't say I could tell if it added esters but it certainly has not added a bad flavor.

I am using torrefied flaked corn in my mash, so no cooking or gelatinizing, just good old mashing. I use the backset to sparge the grains or more commonly just to dilute the mash a bot before I pitch. It's rare I distill and mash on the same day. For rum I heat up the dunder though, and use it to dissolve the panela.

if you are mashing for an hour at 148 F you will kill most of the lacto, 99%. If you are going to 165F or so for a sparge you are also good.

subbrew wrote: ↑Fri Apr 11, 2025 11:28 am if you are mashing for an hour at 148 F you will kill most of the lacto, 99%. If you are going to 165F or so for a sparge you are also good.

I am usually mashing at 152F for 90 minutes, I should be good! Thanks subbrew! Appreciate it!