New Giveaway - Wort Monster Conical Fermeneter!

Home Brew Forums > Home Brewing Beer > Brew Science > Lactic Acid and Specific Gravity




Reply
 
LinkBack Thread Tools Display Modes
Old 01-31-2010, 04:19 PM   #1
Bsquared
Feedback Score: 0 reviews
 
Bsquared's Avatar
Recipes 
 
Join Date: Oct 2006
Location: San Diego
Posts: 1,803
Liked 52 Times on 49 Posts
Likes Given: 20

Default Lactic Acid and Specific Gravity

I recently started playing with sour mashing, My first sour mash I let it run a whole week. When I checked the gravity with my Refractometer It said the SG would be 1.068. I was shooting for about 1.040 so I figure the Lactic acid was contributing to this number.

I fermented the boiled runnings for One week so far, and took a gravity reading using my Hydrometer and It read 1.030. The beer tasted quite sour, but did not have much sweetness. I know I got a good fermentation, because this batch blew off. So I'm assuming that the lactic acid is contributing to the gravity, but how much?

Any one have any good data on Lactic acid and SG? I looked it up and the Chemistry hand book stated that it has a SG of 1.050. But is that a 1M solution?



__________________
Bsquared is offline
 
Reply With Quote Quick reply to this message
Old 02-04-2010, 03:25 AM   #2
Bsquared
Feedback Score: 0 reviews
 
Bsquared's Avatar
Recipes 
 
Join Date: Oct 2006
Location: San Diego
Posts: 1,803
Liked 52 Times on 49 Posts
Likes Given: 20

Default Little experiment

So i bought an 88% Lactic acid solution at the LHBS yesterday, and did some measurements.

8.8% lactic acid has a SG of 1.015. This is a lot of Lactic acid way more than what would be in a sour mash so I diluted it down in a solution of 100g/L dextrose and got these #

100g/L dextrose 1.022
100g/L dextrose +8.8% Lactic acid 1.045
100g/L dextrose +4.4% Lactic acid 1.035
100g/L dextrose +2.5% Lactic acid 1.030

50g/L Dextrose +4.4% Lactic acid 1.015

I need to do some math to get a correction factor.



__________________
Bsquared is offline
 
Reply With Quote Quick reply to this message
Old 05-07-2013, 04:58 PM   #3
ryanhope
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jan 2013
Location: Albany, NY
Posts: 243
Liked 23 Times on 18 Posts
Likes Given: 25

Default

So correct me if I am wrong, but it seems like for each 1% of lactic acid the gravity rises by ~2.5 points.

__________________
ryanhope is offline
 
Reply With Quote Quick reply to this message
Old 05-07-2013, 05:06 PM   #4
ajdelange
Senior Member
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: McLean/Ogden, Virginia/Quebec
Posts: 5,199
Liked 452 Times on 371 Posts
Likes Given: 13

Default

88% lactic acid has a density of about 1.206 g/cc at room temperature.

__________________
ajdelange is offline
 
Reply With Quote Quick reply to this message
Old 05-08-2013, 06:40 PM   #5
ryanhope
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jan 2013
Location: Albany, NY
Posts: 243
Liked 23 Times on 18 Posts
Likes Given: 25

Default

Quote:
Originally Posted by ajdelange View Post
88% lactic acid has a density of about 1.206 g/cc at room temperature.
I am not sure what that tells me. What I want to know is if I am growing lacto in some wort and I am monitoring my gravity, how will the gravity change with increases in lacto.
__________________
ryanhope is offline
Brewing_on_the_Internet Likes This 
Reply With Quote Quick reply to this message
Old 05-08-2013, 07:03 PM   #6
Bsquared
Feedback Score: 0 reviews
 
Bsquared's Avatar
Recipes 
 
Join Date: Oct 2006
Location: San Diego
Posts: 1,803
Liked 52 Times on 49 Posts
Likes Given: 20

Default

Quote:
Originally Posted by ryanhope View Post
I am not sure what that tells me. What I want to know is if I am growing lacto in some wort and I am monitoring my gravity, how will the gravity change with increases in lacto.
Its not a liner relation ship, so its hard to say depending to the % lacto in the beer. I did this before but I can't remember the numbers right now, but I titrated down lactic acid disolved in beer to see what % of lactose was required for the desired level of sourness I was trying to achieve, I'll have to look it up and see if I can find it, but I think it was less than 1-2%.

I plugged these # into excel and made a linier equation

y = -0.0021x + 1.0412 where y is % lactic acid and X is SG.

how to use this??? I don't know for sure. I think the talk home message is that lactic acid will increase your gravity readings.
__________________
Bsquared is offline
 
Reply With Quote Quick reply to this message
Old 05-09-2013, 03:04 AM   #7
smokinghole
Senior Member
Feedback Score: 0 reviews
 
smokinghole's Avatar
Recipes 
 
Join Date: Nov 2009
Location: Lucid Dream Land
Posts: 2,784
Liked 98 Times on 81 Posts
Likes Given: 10

Default

The best way to go about figuring out the attic acid contribution is a titration. That will give you an idea of acid content, but not super accurate because of the complexity of the mixture. Then once you have a round about estimate of acid you can use that to figure the gravity contribution. There may be a kit to specifically courage lactic acid, maybe a yogurt industry based item, or other type acid fermentation QA related kits.



__________________

Going through life is hard.
Going through life stupid is harder.

smokinghole is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
How much lactic acid needs to be used before you can taste it? kal Brew Science 23 12-20-2011 07:32 PM
How much Lactic acid ? Bru Brew Science 14 08-06-2009 11:40 PM
When to add Lactic acid? OdinsBrew Beginners Beer Brewing Forum 2 01-13-2009 02:55 PM
where can i get lactic acid Surfman Recipes/Ingredients 2 06-11-2008 10:52 PM
Lactic acid kabert7 Extract Brewing 2 07-26-2007 02:23 PM