Author Topic: astringency  (Read 4908 times)

Offline dmtaylor

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Re: astringency
« Reply #15 on: January 02, 2013, 01:47:23 PM »
Evaporation rate is a function of at least two variables: 1) rate of added heat, e.g., how big is your flame or heat source, and 2) surface area of the boiling wort, i.e., directly proportional to the square of the radius of the kettle.  The surface area being heated also plays a role, e.g., if you were able to throw a heating coil into the beer itself, that beer is going to cook pretty dang quickly due to all that extra heated surface area.

The typical homebrewer uses a pretty standard burner and a kettle that is maybe 16 to 20 inches in diameter, to make roughly 5 or 6 gallons, yes?  And this typical homebrewer will lose roughly 0.8 to 1.0 gallons per hour with this typical setup, so they'll start with 6 or 7 gallons.  With a double batch, they'd probably need two kettles, which would require 12 to 14 gallons.  But not 16!  But if the kettle size is increased from 16 inches to, say, 24 inches, then the boiloff rate with the same rate of added heat will increase by a ratio of 12 squared over 8 squared = 144/64 = 2.25 times the typical guy.  So maybe the bigger kettle will lose closer to 2.25 gallons per hour instead of just 1 gallon, due to the larger surface area of the boiling wort alone.

My guess is that your setup is even more robust than this, in one or more ways.  To be able to boil 16+ gallons at one time, and still boil off 5 gallons in one hour, you've got to have a hotter heat source, and a larger diameter kettle, yes?  Hence your ability to have a really high boiloff rate.  If there's any way you can reduce the size of your kettle diameter, or turn down the heat, then you won't need to sparge so much, and your problems may be reduced.

With respect to sparging... yes, you want the volumes to be equal.  First runnings = second runnings, and if you do two sparges, then divide in 1/3 so that the first two runnings = third runnings.  Personally I only ever do a double sparge when I'm making a beer with an OG more than 1.100.
Dave

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Offline weithman5

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Re: astringency
« Reply #16 on: January 02, 2013, 01:58:28 PM »
when i boiled using gas i lost about 1g/hr.  i am more gentle with my electric and hit about 1/2 gallon per hour. if you really need to have so much fluid just for the boil off i would just add plain water without it going through the mash. maybe check the gravity of your runnings to see if you have enough sugar to hit your og. i bet the extra sparge has low specific gravity compared to your first runnings and is not adding significantly.
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Offline Kaiser

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Re: astringency
« Reply #17 on: January 02, 2013, 02:18:04 PM »
Tannins are the predominant cause of astringency in brewing.  They are complex organic molecules that can complex with metal ions and precipitate out of solution.  They also complex with proteins. 

For the past several years, I was confused as to why my morning cup of tea tasted better at work than at home.  At home I have RO water in the kitchen and at work I have typical Midwestern hard water.  On the outset, I assumed that RO water would make better tea since it has very little alkalinity.  But invariably, the tea made with the hard tap water was smoother and less astringent even though they are otherwise identical (temp, teabag, etc).   

That is an interesting thought. It is known that tea made with hard water will taste softer and less astringent. As you mentioned, that is likely due to the complexing of calcium/magnesium with the polyphenols.

In Red's case, I think it is the amount of sparging he does. What can be done is to either sparge less or don't fully drain the grain bed between sparges. I.e. keep more of the wort in the grains before more water is added. That way more of the buffer capacity is retained. This will hurt your lauter efficiency and with it your brewhouse efficiency. But that is intended since you will be sparging less aggressively.

Kai


Offline denny

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astringency
« Reply #18 on: January 02, 2013, 02:29:11 PM »
:o  That boiloff rate is insane! 

I like your theory....  what typical boil-off rates are you guys getting? Or to put it another way, how much liquid are you guys starting with, to end up with 10.5 or 11 gals into the fermenter?  Obviously not 16gals...

I boil off about 1.5 gal./hr.
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Offline redzim

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Re: astringency
« Reply #19 on: January 02, 2013, 02:33:26 PM »
Will partially covering my kettle to reduce boil-off rate adversely impact the whole DMS/SMM thing? (not sure I have those acronyms correct!)

Offline redzim

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Re: astringency
« Reply #20 on: January 02, 2013, 02:34:50 PM »
In Red's case, I think it is the amount of sparging he does. What can be done is to either sparge less or don't fully drain the grain bed between sparges. I.e. keep more of the wort in the grains before more water is added. That way more of the buffer capacity is retained. This will hurt your lauter efficiency and with it your brewhouse efficiency. But that is intended since you will be sparging less aggressively.

Kai

Will doing 2 or 3 sparges (i.e. 3 or 4 run-offs, total, rather than just 2) be a help?

Offline denny

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astringency
« Reply #21 on: January 02, 2013, 02:46:55 PM »
Will partially covering my kettle to reduce boil-off rate adversely impact the whole DMS/SMM thing? (not sure I have those acronyms correct!)

A study I read years back said that as long as it's 15% open you'll be OK.
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Offline Alewyfe

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Re: astringency
« Reply #22 on: January 02, 2013, 02:56:51 PM »
Very informative post. Glad you asked the questions Red.
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Offline Kaiser

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Re: astringency
« Reply #23 on: January 02, 2013, 03:06:41 PM »
In Red's case, I think it is the amount of sparging he does. What can be done is to either sparge less or don't fully drain the grain bed between sparges. I.e. keep more of the wort in the grains before more water is added. That way more of the buffer capacity is retained. This will hurt your lauter efficiency and with it your brewhouse efficiency. But that is intended since you will be sparging less aggressively.

Kai

Will doing 2 or 3 sparges (i.e. 3 or 4 run-offs, total, rather than just 2) be a help?


No, I think that will be the same since you will be using more water for each sparge if you sparge less.

You can always reduce the boil-off by reducing the heat.

Kai

Online hopfenundmalz

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Re: astringency
« Reply #24 on: January 02, 2013, 03:52:34 PM »
Will partially covering my kettle to reduce boil-off rate adversely impact the whole DMS/SMM thing? (not sure I have those acronyms correct!)

A study I read years back said that as long as it's 15% open you'll be OK.

And the production breweries are less.
http://byo.com/stories/wizard/article/section/121-mr-wizard/2078-im-currently-all-grain-brewing-and-ive-been-getting-a-rather-high-evaporation-rate
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Offline weithman5

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Re: astringency
« Reply #25 on: January 02, 2013, 04:12:21 PM »
 So if you want more volume before the onset of boiling I would simply add water to the kettle instead of running extra sparge water through the grain bed.

this is from the above article which is a better description of what i was trying to suggest
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Offline paul

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Re: astringency
« Reply #26 on: January 02, 2013, 06:59:24 PM »
So if you want more volume before the onset of boiling I would simply add water to the kettle instead of running extra sparge water through the grain bed.

I have a fairly high boil off rate--1.3 to 1.4 gal/h--so i usually do this as well, particularly for low-gravity beers.

Offline redzim

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Re: astringency
« Reply #27 on: January 02, 2013, 07:18:33 PM »
So if you want more volume before the onset of boiling I would simply add water to the kettle instead of running extra sparge water through the grain bed.

this is from the above article which is a better description of what i was trying to suggest

Great tips coming in, talk about crowd-sourcing! thanks all... I think I'll take the following ideas and try to put them into practice:

1) Try to only boil off 2 or 2.5 gal/hr rather than 5 with a combination of reduced heat and an added lid... which begs the question, how much of a boil do I need? With my steam-jacketed kettle, I can change, within literally 30-60 seconds, from just a mild simmer around the edge (the jacket) to a full (and I mean FULL) rolling boil.  I usually aim for enough heat to keep the middle of the kettle bubbling (which means the circumference is definitely bubbling good too), but I can definitely turn it down to more of a simmer.... but how much "boil action" do I need for hop resin extraction?

2) So in order to only boil away 2 gallons, I'll collect less wort, which will hopefully balance out my run-off volumes better...

3) If I can't get the boil low enough, I'll still maybe just collect 12 or 13 gallons, and then add water to the kettle preboil as suggested by the BYO article and Don Weithman.  Which begs the question: I assume that water would need to be the same water as I mashed and sparged with, i.e. if it's my tap water, use that, or if it's a recipe built on distilled water plus minerals, use that....?

4) Acidify my sparge water down to 5.5, which sounds like a good thing to be doing in any case...

Did I miss anything?
-red

Offline tschmidlin

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Re: astringency
« Reply #28 on: January 02, 2013, 09:38:30 PM »
how much "boil action" do I need for hop resin extraction?
None, the hops acids will be converted regardless of the mechanical action.  It is more important for blowing off DMS, but it doesn't need to be jumping out of the kettle for that either.  As long as it is visibly turning over a bit, that is good enough for me.

For top up water you can do whatever you like, you'll just want to account for any differences in your recipe design.
Tom Schmidlin

Offline weithman5

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Re: astringency
« Reply #29 on: January 03, 2013, 12:24:02 PM »
i don't know that i would get too hung up on the features of the water other than making sure there is no chloramine/chlorine, unless it is a particular flavor you are looking for. i would assume your ph adjustments are really pertinent to the water being used in the mash

i don't think you need an aggressive boil off. again with my electric system it is not much of a boil off at all, i think 1/2 g per hour.
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