Measuring Sugar in a wort? - Home Brew Forums

 Home Brew Forums > Measuring Sugar in a wort?

09-16-2009, 05:50 AM   #1
Inarus
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Jul 2009
Texas
Posts: 7

So I'm studying yeast for my biology class. I managed to talk my professor into allowing me to study the effects of sugar in a wort compared to the alcohol content of the finished product. Logic tells me the more sugar the more alcohol and most of the research I have done has backed this up. But What the hell, I want to try it. So dang, I have to brew 10 gallons of beer for a class, what a shame! But I'm running into the problem of how do I measure the sugar content of the wort? Any ideas? Is there a probe out there that will do it? Will a simple diabetes tester do it?

09-16-2009, 05:59 AM   #2
z987k

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Feb 2007
Anchorage
Posts: 3,518
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Quote:
 Originally Posted by Inarus So I'm studying yeast for my biology class. I managed to talk my professor into allowing me to study the effects of sugar in a wort compared to the alcohol content of the finished product. Logic tells me the more sugar the more alcohol and most of the research I have done has backed this up. But What the hell, I want to try it. So dang, I have to brew 10 gallons of beer for a class, what a shame! But I'm running into the problem of how do I measure the sugar content of the wort? Any ideas? Is there a probe out there that will do it? Will a simple diabetes tester do it?
uh... is this for college or HS?
American brewer's usually measure the sugar content as specific gravity. You can get a hydrometer from any homebrew store to measure this. In europe and on a professional scale, Plato is usually the preferred measurement with is the %sugar in solution.
Brix is sometimes used, but is slightly misleading as Brix actually measures % sucrose in solution and this is not what wort really is, but in reality it works out close enough that brix = plato for as accurate as I care to be.

However, I hate to ruin your experiment but the more sugar in your starting solution, the more alcohol the yeast will make until they have reached their attenuation limit or alcohol tolerance limit. This has been known for hundreds if not thousands of years.

The formula for alcohol content in terms of specific gravity even shows that the more sugar, the more alcohol. (OG-FG * 131).

Have you ever made beer before? I would suspect you would have a hydrometer or refractometer if so. It takes a decent amount of equipment to make beer, and unless you do want to start this hobby, it looks like a pretty expensive experiment to me. You might consider just doing a sugar and water solution and then adding yeast for the purposes of the experiment to keep costs down. The results will be the same. (or do apple juice if you want a drinkable product afterwards.)

09-16-2009, 04:09 PM   #3
Inarus
Recipes

Jul 2009
Texas
Posts: 7

Z,

I have made beer before, this will be my 5th and 6th batch. I'm doing one method pure extract where the other method will use mini-mash (these are the terms my home brew supply store uses). I figured this would be the case, I just wanted to have an excuse to brew 10 gallons of beer. (PS: This is for a college class).

And I do have a hydrometer. So what you're saying is the OG is a measure of sugar content? And then using the formula gives me the alcohol content? I can just use my hydrometer to find the amount of sugar in the wort?

09-16-2009, 04:36 PM   #4
Bsquared

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Oct 2006
San Diego
Posts: 1,851
Liked 67 Times on 59 Posts

Do you have access to a mass-spec? then you can determine the percentage's of the different sugars in the wort. A hydrometer only measures specific gravity for a solution, and wort is mixture of a lot of different compounds like simple and complex carbohydrates, lipids, and proteins.

I'm sure you can find a Chemistry grad student that would be willing to help you analyze the composition of your wort using a mass-spec. For a six or twelve pack of the finished product. If you did that, then you could analyze sugar utilization during the fermentation process. i.e. yeast consume maltose at a faster rate then other sugars during the first x hr's of fermentation, then move on to glucose...

09-16-2009, 08:29 PM   #5
david_42

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Oct 2005
Oak Grove, Oregon, USA
Posts: 25,599
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If you measure specific gravity in Brix, you know the percentage of sugar. 10 Brix is roughly 1.040. Many hydrometers have a Brix scale.
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09-16-2009, 08:37 PM   #6
JLem

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Jan 2009
Attleboro, MA
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Quote:
 Originally Posted by Inarus Z, I just wanted to have an excuse to brew 10 gallons of beer. (PS: This is for a college class).
Man, that seems like one gullible prof. Unless, of course, you bribed him/her by promising to share the results of your experiment!
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