Post boil gravity lower than pre boil gravity with BIAB

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cgdntx

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First, the details -

Using Brewer's Friend, 2.5 gallons to fermenter SMaSH. Grain is 5 lb. Maris Otter crushed at LHBS.
BIAB, so no sparge. Hour mash ~152 (or as close as I could keep it)
Hit pre boil expected 1.038 and expected volume after draining / small squeeze.
1 hour boil resulted in 1.037 OG after cooling.

The rest of the story -

This is my second brew this time around. First one was an identical recipe except I used Golden Promise as the malt. It came out perfect, and I hit expected numbers at every step.

In that first brew, I did two things different as far as the process goes. First, I had a heck of a time (hours) getting the wort cooled, which I fixed this time. Second, I reconfigured my equipment profile to have a gallon of loss from kettle to fermenter so I didn't have to worry about tilting and pouring and the mess that my clumsy butt made last time.

In doing all this, I thought there was a happy byproduct of it that when I fixed my cooling, there was a lot of "stuff" that fell out of the wort and didn't get into my fermenter because it all went down into the loss at the bottom of the kettle.

On to the stupid questions -
- What is this "stuff" that dropped out when I cooled it?
- Is this something I need to have in my fermenter?
- If so, how to I get it there without dumping the whole kettle? Just stir the crap out of it while it's transferring?

Thanks in advance.
 

Sammy86

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What is this "stuff" that dropped out when I cooled it?
That would be cold break...proteins from the wort that come out of solution when cooling.
Is this something I need to have in my fermenter?

You don't need to have it but its not going to hurt anything either, it'll drop out during fermentation.

how to I get it there without dumping the whole kettle? Just stir the crap out of it while it's transferring?

Best way is filter it, but like I said earlier it isn't going to hurt the final product.

As for your lower reading it's probably from the top of the wort and it wasn't mixed well. Happened to me this past brew...if you know how many points you gain during a normal brew you can estimate what the OG is based on previous boils.
 

Brushwood Brewing

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I second Sammy86 on the sediment: proteins from the cold break. Don't worry about them. Try to leave most of the sediment behind when transferring to fermenter, but no need for any filters. More will drop out in the fermenter over time. When bottling from fermenter, again try to leave most of the sediment behind, but getting some into the bottles is actually good nutrient for the yeast. Some homebrewers have done side-by-side experiments and shown the desired amount of sediment transferred is a personal preference regarding taste, and can actually vary by style. It's subtle, so not something to focus on at this point.

Regarding the post-boil gravity being lower than the pre-boil gravity: Did you leave the lid on during the boil?
 
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cgdntx

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Thanks, both of you, for the quick responses. Small batches mean more brew days, and I'm planning on another tomorrow so they can ferment while I'm out of town. I'm hoping to fix whatever needs fixing before that.

As for your lower reading it's probably from the top of the wort and it wasn't mixed well.
It was from the top. I thought it would have been mixed good enough at the time I took it, but I could definitely be mistaken about that. It makes sense, though. I'm wondering if I'm working with too small of batches to have that much loss in transfer even if it is planned for.

Did you leave the lid on during the boil?
Yes, for almost all of it. I didn't think that would matter that much, but I guess that would affect boil off, huh?

A .012 miss seems like a lot, though.
 

CascadesBrewer

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Second, I reconfigured my equipment profile to have a gallon of loss from kettle to fermenter so I didn't have to worry about tilting and pouring and the mess that my clumsy butt made last time.

Does this mean that you started with one gallon more volume in the mash? Most software is built around you understanding the efficiency of your process. You tell it that you get 70% efficiency and it calculates a OG based on that 70% efficiency. If you used the same amount of grain but added 1 extra gallon of water, and left behind more wort in the kettle, that would lower your efficiency. That is not necessarily a good or bad thing, but you would just need to build your recipes around your actual measured efficiency (and losses, boil off, etc.).

Assuming you boiled off some water, I would expect your post-boil gravity to be higher than pre-boil. So, as mentioned, this points at an issue with the measurement. Make sure you are consistent with your process. Stir the wort before. If you are using a hydrometer, be sure to cool the wort to close to the calibration temp.
 

CascadesBrewer

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- Is this something I need to have in my fermenter?

As far as transferring trub goes...I recently brewed these two batches. The plan was a split wort with Verdant and S-04 but I had some transfer issues learning to use my new kettle with a ball valve (I need about 3 gallons of wort in the kettle for the level to be high enough for a siphon to transfer out of the ball valve...I think I have a solution to this moving forward). I ended up pouring the wort through a strainer into the second fermenter, so I got a bunch of trub.

I scraped the split yeast plan and just fermented them both with S-04. I added a little more yeast to the first fermenter, but looking at this picture it seems to have 1/3 more wort than the second fermenter. Differences could be 99% due to the volume differences, but the batch with the trub fermented faster, had less esters (might be lower diacetyl), and is significantly clearer after a few weeks in the keg.

I would not read too much into this one poorly executed experiment, but it at least let me know that my common practice of transferring my wort through a strainer to remove hop matter does not ruin the final product. Some Brulosophy experiments seem to indicate that some trub is helpful for fermentation. Some people claim that very clear wort makes for a better beer.


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cgdntx

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Thanks again for all the input.

I think I have a few things going on, and it was a combination of me using the brewing software incorrectly, taking a bad reading (I have to have read my pre-boil incorrectly), and making multiple changes at the same time so I couldn't nail down what happened.

I'll see how it goes tomorrow.
 

AlexKay

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What I have heard is that leaving the cold break in the fermenter provides nucleation sites for CO2, resulting in more churn in the fermenter, and thus a healthier fermentation.
 
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cgdntx

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Quick update..

Yall were on the money with everything.

Took what was said here and really paid attention to what was going on yesterday and corrected where I could. Inconsistent boil, math using bad assumed numbers for my equipment and efficiency, flat out taking some measurements incorrectly......

I think the successful brew that I was comparing to either wasn't as on point as I thought it was, or just some really dumb luck 🤣

Anyway, knowing what to look for helped me really focus on some areas and I learned a TON and had a good brew day.

Yall are gold. Thanks, again.
 
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