Author Topic: boil volume question  (Read 1436 times)

Offline redzim

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boil volume question
« on: January 13, 2013, 11:39:42 AM »
OK from this previous thread (http://www.homebrewersassociation.org/forum/index.php?topic=14292.0) I am realizing that my processes are a little abnormal compared to the average homebrewer. To recap, the main issue is my large kettle which has a huge (30-40%) boil off rate, which caused me (up until my most recent brew yesterday, Maibock) to oversparge... that is, collect 16-17gals to boil down to 11gal.  This caused astringency in many beers even though I got great efficiency.  Then the astringency from oversparging got further concentrated by the boil.

So based on suggestions from this forum, I sparged only until I collected 12gal (which would put me in the ballpark of other 10gal brewers, I guess), then I added 5 gallons water to the kettle before starting the boil (for various reasons it is basically impossible to reduce my boil off rate, in case you're wondering). (I also acidified my sparge water with lactic acid for the first time, getting in from ~7.5 down to ~5.7, which will help astringency also)

Now I use Kaiser and Martin's water spreadsheets heavily. What I did yesterday was add minerals to the "dilution" water (which I added to the kettle pre-boil) in the same proportions that I did to the mash and sparge water.  Thinking about it more, I think this may be wrong?  If I enter data into those spreadsheets as if I'm collecting 12gal pre-boil, that obviously makes my mash pH and everything work out, as well as setting the flavor profile.  So if I add more minerals preboil, I am now thinking, that screws everything up and sort of "concentrates" my minerals. Perhaps what I should be doing is adding distilled water as my dilution, so the minerals don't get played with... because the only reason I'm adding water to the boil is so I have enough wort to ferment after the boil.... so it just be be distilled that evaporates off... correct assumption? Or am I off here?  (previously, I entered data in the water spreadsheets as if I was collecting 16-17gal, and they nicely gave me lots of stuff to add to my sparge water, which again got concentrated in the boil...  if Martin or Kai could clarify how their sheets work it would help here... I guess they assume most people have a "normal" boil off rate)

So that got me thinking further: I bet I'm messing with my hop utilization by having such a big preboil volume....  so maybe instead of adding 4 or 5 gallons right at the start of the boil, I should add it a half gallon at a time during the boil, so I never have more than maybe 12-13 gal in the kettle...  this would then let me mimic the average homebrewer who boils from 12 gal down to 10.5, or so... 

any thoughts?
-red


Offline Alewyfe

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Re: boil volume question
« Reply #1 on: January 13, 2013, 11:52:26 AM »
Any kettle additions of chemicals are for flavor only. You are no longer worried about pH as you have addressed that in the mash and the sparge. Think of a perfectly flavored soup. When it is too thick, would you add salted and peppered water to it? No, because as you boiled you'd be concentrating the seasoning and throwing it out of balance.

As for hop utilization, that, I would think, requires trial and error. You have a pretty unique situation.
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Offline paul

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Re: boil volume question
« Reply #2 on: January 13, 2013, 10:27:02 PM »
Red,

You are correct that minerals added to your kettle make up water are superfluous.  If you assume that all of the minerals from your mash are rinsed into the kettle, then you only need to add a little more to get the same concentration in your kettle, based on the final kettle volume.  For example, assume you are brewing a 10-gallon batch (fermenter), and need to have 11 gallons in your kettle (final).  Next assume your mash volume is 7 gallons, and your water calcs called for 7 g of a mineral, or 1 g/gal.  That means you'll want 11 g in the kettle when the batch is done.  Assume all 7 g are rinsed into the kettle, leaving you 4 g short.  So you just add the 4 g to the kettle.  If you wanted to add it to the sparge water, you might want to boost this a little to account for the sparge water that's left in the mash tun.

For bitterness, I think it's actually a benefit that you're boiling off so much.  Your boil volume will be larger, so your boil gravity is lower, meaning greater utilization.  Most brewing calculators can adjust for this.

Offline mabrungard

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Re: boil volume question
« Reply #3 on: January 14, 2013, 08:28:01 AM »
Red,

You have a unique case because of the excessive boil-off rate.  It sounds like you are mashing and sparging now with appropriate water volumes for normal brewing conditions and then adding water with low mineralization to make up for that high boil-off loss.  That makes sense, if I've understood this procedure properly. 

Since there are a variety of reactions and processes that alter the concentrations of ions in the finished wort compared to the starting water, its crazy to try and predict or assume what those ion concentrations are in the finished wort.  But if we standardize on the starting water concentrations, at least some of the picture can become clearer.  This is the case of those historic brewing cities.  They started with whatever the water source gave them and brewed beer.  Basing everything on starting water quality is similar to that condition.

In your case, I would only add minerals based on the 'normal' mashing and sparging water volumes.  Those ions will be depleted or condensed based on whatever processes occur in the mashing.  I would add as pure a water as possible without any added minerals to the kettle to make up for those boil-off losses in excess of the more typical ~1 gal/hr rate that many homebrewers experience. 

That should get you somewhere back to par for the course. 

Enjoy!
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Offline redzim

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Re: boil volume question
« Reply #4 on: January 14, 2013, 08:42:52 AM »
Red,

You have a unique case because of the excessive boil-off rate.  It sounds like you are mashing and sparging now with appropriate water volumes for normal brewing conditions and then adding water with low mineralization to make up for that high boil-off loss.  That makes sense, if I've understood this procedure properly. 

Yes you've understood exactly.

In your case, I would only add minerals based on the 'normal' mashing and sparging water volumes.  Those ions will be depleted or condensed based on whatever processes occur in the mashing.  I would add as pure a water as possible without any added minerals to the kettle to make up for those boil-off losses in excess of the more typical ~1 gal/hr rate that many homebrewers experience. 

That should get you somewhere back to par for the course. 

Enjoy!

That's what I plan to do.  Distilled water should work for being "as pure as possible", right?

thanks
red

Offline mabrungard

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Re: boil volume question
« Reply #5 on: January 14, 2013, 10:26:05 AM »
That's what I plan to do.  Distilled water should work for being "as pure as possible", right?

thanks
red

That is the best, but going with RO is close enough. 
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Offline redzim

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Re: boil volume question
« Reply #6 on: January 14, 2013, 11:07:42 AM »
That's what I plan to do.  Distilled water should work for being "as pure as possible", right?

thanks
red

That is the best, but going with RO is close enough.

It's actually easier for me to get distilled than RO.... so we're good...

Offline kylekohlmorgen

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Re: boil volume question
« Reply #7 on: January 14, 2013, 02:25:36 PM »
Wouldn't it be easier to just figure out how to reduce your evaporation rate?

You said your large kettle contributed to this; can you adjust your burner?

I would think such an active boil would contribute off-flavors, even if you figured out how to compensate with more water. You also will probably save some cash in propane refills and bottle water!
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