Increase ABV of existing homebrew? - Home Brew Forums
Register Now For Free!

Home Brew Forums > Home Brewing Beer > Brew Science > Increase ABV of existing homebrew?

Thread Tools
Old 12-14-2011, 06:49 PM   #1
Jul 2011
South bend, In
Posts: 6

Just a theoretical chemistry question.

Is it possible to take an existing homebrew, or any beer for that matter, add sugar, then pitch yeast to increase alcohol content?

Not that I'm planning on doing it ... just curious if possible.

Basically you would be re-fermenting an alcoholic beverage that has already fermented.

Any thoughts?

Reply With Quote
Old 12-14-2011, 06:56 PM   #2
david_42's Avatar
Oct 2005
Oak Grove, Oregon, USA
Posts: 25,599
Liked 158 Times on 148 Posts

That's all there is to it. But you run the risk of throwing the beer out of balance and turning a good thing into high-alcohol plonk. Occasionally, I've added some sugar to dry out a beer that had too many fermented sugars at the end.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"

"I would like to die on Mars, just not on impact." Elon Musk

Reply With Quote
Old 12-14-2011, 07:10 PM   #3
IffyG's Avatar
Oct 2009
Posts: 1,393
Liked 62 Times on 51 Posts

Considering you'd probably be adding oxygen in the process and oxygen+beer=oxidation I'd say it's not something you'd want to do.

Reply With Quote
Old 12-14-2011, 07:30 PM   #4
Aug 2010
Fort Worth, Tx
Posts: 282
Liked 11 Times on 10 Posts

This is essentially what alot of people do when brewing big beers like triples. They let the yeast ferment out most of the maltose then add the simple sugar when they are approaching their final gravity.

On the CYBI show where they cloned DFH 120 min IPA, the brewer let it ferment almost all the way out then fed it sugar everyday for I think 2 weeks. I'm not sure if this is the way DFH does it.

The difference between this and using a totally finished beer and adding sugar and yeast is that they are using the existing active yeast and just prolonging the fermentation to raise ABV.

People do this rather than add all the sugar at the end of the boil because yeast have a tendency to eat the most readily available food, which is simple sugar. Then they have a hard time with the more complex maltose that is still around.

Think of it as giving your kid with a plate of vegetables and cake. They will fill up on cake and not eat the veggies. You need force them to eat the veggies first then give them the cake. Kids will always have room for desert and yeast usually have the capacity to eat simple sugars even in a high ABV wort.

carrotmalt Likes This 
Reply With Quote
Old 01-10-2012, 10:34 PM   #5
Dec 2011
Florence, Kentucky
Posts: 1

Sounds like a great idea. I may try this on my next batch since im already 3 days into my secondary. What is a good simple sugar to use and about how much each day?

Reply With Quote
Old 01-10-2012, 10:39 PM   #6
AnthonyC's Avatar
Jul 2009
Posts: 81
Liked 2 Times on 2 Posts

This is exactly what happens when people bottle. Add corn sugar to already fermented beer.

Reply With Quote
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
MSG in homebrew Hockeyhunter99 Brew Science 14 04-12-2011 02:11 AM
CaCO3 vs NaHCO3 to increase residual alkalinity - tradeoffs? greenbirds Brew Science 5 09-04-2009 04:30 PM
Homebrew Myths menschmaschine Brew Science 19 04-23-2009 04:45 PM

Forum Jump