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Old 09-04-2007, 09:28 PM   #1
Jan 2007
Posts: 20

I have made a few batches of beer from those can from coopers and when i measure the alcohol % its always a bit low like 3% i was wondering what controls the alcohol % so i can make them a bit stronger in alcohol

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Old 09-04-2007, 09:33 PM   #2
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Mar 2007
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In short the amount of extract you put into the batch. More sugar= more for the yeast to eat on.

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Old 09-04-2007, 09:33 PM   #3
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The amount of added fermentables is what controls the amount of alcohol. Like a Cooper's recipe calls for an additional 1kg of fermentables ( Cooper's dextrose, Cooper's brewing sugar, Cooper's brew enhancer, etc... )

Basically to make more alcohol, you just add more fermentables.

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Old 09-04-2007, 10:02 PM   #4
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Let's not be short-sided.

OK, so the amount of fermentable sugar in the beer provides the potential for higher alcohol, but it's the alcohol tolerance of the yeast that determines the actual ABV. Weaker yeast cells die off from the alcohol level so ultimately the ABV is dependant on how tolerant the yeast are to alcohol.

Some yeast, like Turbo or Champagne and others can tolerate alcohol levels in the mid to high teens.

This is why people take gravity readings. At the beginning you can see potentially how high an ABV you could achieve. The final gravity reading shows how much sugar was converted prior to the yeast dying down to a level to where they can simply convert no more.

Also, the fermentability of the sugar plays a factor. Wort isn't just sugar and water, there's all sorts of matter that can't be digested by yeast. This is why wort can't get to the gravity of water or lower.

Honey can ferment to a level where the gravity is lower than water. Almost all of the honey is digested into alcohol, so the gravity can be (for example) .990 when water is 1.000.

Other times, brewers add non-fermentable sugars for "mouthfeel" (i.e. malto-dextrine) or to provide sweetness (i.e. Lactose).
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Old 09-04-2007, 11:15 PM   #5
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A hydrometer does not measure alcohol percentage. The difference between the original gravity and final gravity can be used to calculate the amount of alcohol.
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Old 09-05-2007, 02:05 PM   #6
St. Jon's Wort
Aug 2007
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Originally Posted by david_42
A hydrometer does not measure alcohol percentage. The difference between the original gravity and final gravity can be used to calculate the amount of alcohol.

My hydrometer measures potential ABV by %. I currently have a bock in my primary and the O.G was 1.050 and it had 6.5% potential ABV.

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Old 09-05-2007, 02:20 PM   #7
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Jon's Wort is right...those hydros (mine at least) has a little scale on there for measuring potential ABV. I never use that scale, but it is on there. I wouldn't rely on it myself, because it cannot take into account the tolerance of the yeast or the proportion of fermentable:unfermentable sugars in your wort.
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Old 09-05-2007, 02:37 PM   #8
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Feb 2007
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The potential alcohol scale on the hydrometer is for wine makers and distillers. The sugars in wine are nearly completely fermentable so the original gravity directly translates in to finish ABV. However beer is not completely fermentable so to get the actual ABV of the finished product you need to subtract the final potential from the original potential. Most brewers however just measure the gravity and use a formula or software to get the ABV.
As mentioned for most beers the ABV is directly related to the original gravity. To increase the OG you need to add more sugars. Adding simple sugar like table sugar will result in a dryer beer that can be watery. Adding malt extract will add body and sweetness which should be balanced with additional hops. If you ABV starts getting too high you will get more alcohol flavors and for really big beers the alcohol tolerance of the yeast starts having an effect.


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Old 09-05-2007, 03:23 PM   #9
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Apr 2007
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I would say the brewer controls the abv%, but he delegates most of the actual work to his yeast slaves. They receive no pay, only receiving food and lodging. Some brewers treat their yeast well and get good results, while others do not and achieve poor results. Sorry, I'm in a weird mood.

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Old 09-05-2007, 03:45 PM   #10
Jun 2007
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You fools! As any good brewer knows, alcohol is controlled completely by the little gnome who lives in your airlock. I leave him cookies and milk each night and he makes my brew stronger. Sometimes I even tickle him with a feather to........

Oh! right! Yeast make alcohol. I suggest you read about them here.

The amount of "food" they can eat in the beer determines how much alcohol they will poop out. Also of note, is their alcohol tolerance. If you give them too much food they will not be able to process it all and your beer will be sweet.

The higher the OG the more POTENTIAL alcohol there is. The lower your FG, the more alcohol has been produced.

I have been successful in making REALLY high ABV brews.
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