Spike Brewing 12.5 Conical Fermenter Giveaway - Enter Now!

Home Brew Forums > Home Brewing Beer > General Techniques > All grain gravity readings

Reply
 
LinkBack Thread Tools
Old 03-26-2007, 01:43 PM   #1
delboy
Feedback Score: 0 reviews
 
delboy's Avatar
Recipes 
 
Join Date: Jan 2007
Location: Belfast N.Ireland
Posts: 324
Liked 1 Times on 1 Posts

Default All grain gravity readings

Was thinking about this the other day. I've noticed that when i take a sample of the boiled wort and cool it down to 20C i get high hydrometer readings. But when i let the same sample sit overnight which allowed the trub to completely fall out of suspension the reading was way down, is it possible that we are kidding ourselves about the gravity/fermentables in our beers.

There is ceratinly a lot of proteins in solution when coming out of the mash which will raise the gravity at that point, after boiling there is lots of insoluble proteins floating about to raise the gravity. After pitching there is lots of yeast in suspension to raise the gravity. Surely the boiled sample left overnight to allow trub to fall out is giving the real gravity from sugars ie quite a lot lower???

__________________
delboy is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:13 PM   #2
Ó Flannagáin
Registered User
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jan 2007
Location: Wichita Falls, Tx
Posts: 3,026
Liked 15 Times on 10 Posts

Default

I haven't noticed that. When mine sit overnight they tend to stay almost exactly the same. Just my experience though.

__________________
Ó Flannagáin is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:23 PM   #3
delboy
Feedback Score: 0 reviews
 
delboy's Avatar
Recipes 
 
Join Date: Jan 2007
Location: Belfast N.Ireland
Posts: 324
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by seefresh
I haven't noticed that. When mine sit overnight they tend to stay almost exactly the same. Just my experience though.
That surprises me i can't imagine the trub settling out not affecting the gravity to some extent. Do you have quite a lot of sedimented debris at the bottom of the trail jar? Maybe its something im doing thats producing excessive amounts of proteins that are giving me 'falser' gravity readings. Thing is i use british 2row as my base grain which is famed for its low nitrogen/protein levels.
__________________
delboy is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:29 PM   #4
Ó Flannagáin
Registered User
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jan 2007
Location: Wichita Falls, Tx
Posts: 3,026
Liked 15 Times on 10 Posts

Default

I usually have quite a bit of debris... but honestly, 45 minutes to an hour after I've cooled it down and let it sit, lots of trub has already settled to the bottom.. that's when I take my reading.

__________________
Ó Flannagáin is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:34 PM   #5
clayof2day
Feedback Score: 0 reviews
 
clayof2day's Avatar
Recipes 
 
Join Date: Dec 2005
Location: Madison, WI
Posts: 567
Liked 2 Times on 2 Posts

Default

Plus the trub is suspended in the wort, not dissolved in the wort so it should not affect SG. A log floating in water does not affect the density (SG is a measure of SG).

Matt

__________________
clayof2day is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:35 PM   #6
delboy
Feedback Score: 0 reviews
 
delboy's Avatar
Recipes 
 
Join Date: Jan 2007
Location: Belfast N.Ireland
Posts: 324
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by seefresh
I usually have quite a bit of debris... but honestly, 45 minutes to an hour after I've cooled it down and let it sit, lots of trub has already settled to the bottom.. that's when I take my reading.
Yes mine would be very similar at that stage, it seems to be it that it has to be left overnight to produce the big fall (there must still be lots of much smaller proteins in solution which take longer to fall out keeping the gravity high at about 45-60 mins).
__________________

Last edited by delboy; 03-26-2007 at 02:39 PM.
delboy is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:38 PM   #7
delboy
Feedback Score: 0 reviews
 
delboy's Avatar
Recipes 
 
Join Date: Jan 2007
Location: Belfast N.Ireland
Posts: 324
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by clayof2day
Plus the trub is suspended in the wort, not dissolved in the wort so it should not affect SG. A log floating in water does not affect the density (SG is a measure of SG).

Matt
Stick your hydrometer in porridge see what sort of reading you get even with the oats not dissolved in the milk!! Im guessing it would be pretty high .
__________________

Last edited by delboy; 03-26-2007 at 02:52 PM.
delboy is offline
 
Reply With Quote Quick reply to this message
Old 03-26-2007, 02:52 PM   #8
delboy
Feedback Score: 0 reviews
 
delboy's Avatar
Recipes 
 
Join Date: Jan 2007
Location: Belfast N.Ireland
Posts: 324
Liked 1 Times on 1 Posts

Default

Quote:
Originally Posted by clayof2day
Plus the trub is suspended in the wort, not dissolved in the wort so it should not affect SG. A log floating in water does not affect the density (SG is a measure of SG).

Matt
Hydrometers are used routinely to measure suspensions (ie the amount of clay in silt etc) so i don't think particles need to be dissolved/solvated to cause an increase in the hydro readings.

Also you could argue that the larger trub clumps (those likely to fall out out much quicker) are less likely to keep the reading high as apposed to the much smaller particles which truly are in suspension and therefore take a long time to come out of it (overnight).
__________________
delboy is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
So gravity readings... leapinglords Beginners Beer Brewing Forum 3 09-22-2009 07:21 AM
gravity readings Evan General Beer Discussion 2 09-29-2008 05:25 PM
odd gravity readings Cheeto Beginners Beer Brewing Forum 13 01-30-2008 01:27 AM
Gravity Readings Willie3 All Grain & Partial Mash Brewing 2 09-28-2006 07:08 PM
Gravity Readings PhoenixCoyote Beginners Beer Brewing Forum 2 07-09-2006 11:30 PM