Starter wort from 4th runnings?

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riromero

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Here's an idea I've been pondering for a couple of days.

I usually err on the side of caution and mash my batches with slightly more grain than necessary. So after collecting the wort for the current batch, I still have a gallon or so of 1.020 SG wort left over. Problem is, this is too weak for a starter wort where I'm shooting for 1.040. My idea then is to add more grain to bring the leftover 1.020 back up to 1.040. Question is, how much grain? I can't find a tool that calculates gravity starting from a weak wort.

Even better, could I skip adding additional grain and use 100% cheap adjunct like corn or rice? I wonder if the leftover sparged two-row grain plus 1.020 wort would have enough power left to convert the adjunct, or did the enzymes go into the boil pot already?
 
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riromero

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No, I don't want to use parti-gyle because the specification for the small batch (e.g. 1.040) defines the gravity of the first. From the parti-gyle tables this means my first batch must be high gravity (>1.070). I'd like to just brew whatever type of batch and sparge as normal, then adjust the gravity by adding more grain (preferably adjunct).

Brewing Techniques Parti-gyle article give the maths to calculate runnings from a prti-gyle.
 

kryolla

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Here's an idea I've been pondering for a couple of days.

I usually err on the side of caution and mash my batches with slightly more grain than necessary. So after collecting the wort for the current batch, I still have a gallon or so of 1.020 SG wort left over. Problem is, this is too weak for a starter wort where I'm shooting for 1.040. My idea then is to add more grain to bring the leftover 1.020 back up to 1.040. Question is, how much grain? I can't find a tool that calculates gravity starting from a weak wort.

Even better, could I skip adding additional grain and use 100% cheap adjunct like corn or rice? I wonder if the leftover sparged two-row grain plus 1.020 wort would have enough power left to convert the adjunct, or did the enzymes go into the boil pot already?
why dont you just boil down until your reach 40 points or add some extract to get you to 40. Will each batch fourth runnings be the same so you know how much extra grain you need to add each time?

EDIT
Each type of base grain has a point per pound in a gallon of water, typically around 35. If your efficiency is 75 then its 75% of 35 is 26.25. You need 20 points to get you to 40 so 20/26.25 = .76 or 3/4 lb of grain but its not as simple as adding 3/4 lb of more grain because it will get diluted in the previous runnings.
 
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riromero

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EDIT
Each type of base grain has a point per pound in a gallon of water, typically around 35. If your efficiency is 75 then its 75% of 35 is 26.25. You need 20 points to get you to 40 so 20/26.25 = .76 or 3/4 lb of grain but its not as simple as adding 3/4 lb of more grain because it will get diluted in the previous runnings.
Excellent, thanks.

Anyone know what the conversion power of spent grain might be? Zero maybe?
 

sleepystevenson

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I have been doing this for about the past year or so with great success and financial savings. I usually just add about a gallon +/- of hot water from the HLT to the MLT after I have finished collecting wort / sparging. I let that set for awhile while boiling the wort and then run off the "final runnings" into glass growlers, let it cool, take a reading (usually between 1.010-1.025 depending on the beer being made) then put into plastic 1/2 gallon juice jugs, write the gravity on them with a marker and freeze. If the beer you are making is relatively low gravity (say, under 1.050), your "final runnings" will be pretty low, around 1.010, However, with larger beers, the future starter wort will be definitely high enough to use as a starter as is - 1.020. I always save even the lower gravity stuff, then just add some DME to bring up the gravity to where I would like it, thereby still saving on the DME.

It's nice to be able to pull one of the frozen starter worts out of the freezer in the morning, then after work whip up a "free" yeast starter! Sure beats $12-15 for 3 lbs of DME from the LHBS! Yeast starters for 25-30 gallon batches were getting pretty expensive.
 
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