Intentionally Not Finishing Fermentation?

[JSetzer]

I’ve been wondering if there is any reason to purposely not finish fermentation. Maybe to get a sweeter, lower ABV final product? Is this a technique or will that leave too many “uncleaned” off flavors?

 

[Sacha]

Very new to brewing, but not finishing fermentation is an invitation for bottle bombs. Non fermentable sugar (corn sugar?) will leave a sweet taste with a low abv. I think more typical practice is to mash warmer to give a fuller body, say for a stout.

 

[Golddiggie]

Corn sugar is VERY fermentable. Lactose is a non-fermenting sugar.

IME/IMO, best way to get a 'sweeter' brew is to mash higher in the range. If you're not brewing all grain, then add lactose to the recipe.

 

[JSetzer]

Corn sugar is VERY fermentable. Lactose is a non-fermenting sugar.

IME/IMO, best way to get a 'sweeter' brew is to mash higher in the range. If you're not brewing all grain, then add lactose to the recipe.

Yeah, I thought about that but my plan is to keg. Wondering if that will still be an issue. I agree with you though. An intentional process (mash temp) seems to make more sense than stopping fermentation early. Thanks for the input!

 

[CascadesBrewer]

Arrested Fermentation is the term that I have heard and mostly for brewing very low to no alcohol beers. On a homebrew level it would probably be hard to manage and I would be worried about potential off flavors. The general cycle of yeast is that during fermentation they can produce undesirable compounds. As they run out of sugar and prepare for dormancy, they will absorb the undesirable compounds.

Note that my organic chemistry game is pretty weak, so I am sure the above description is probably not 100% accurate. But pretty much every book on brewing will talk about a clean up stage (or a diacyl rest) to reduce off flavors.

You could potentially back sweeten (add sugars) into the keg, or follow other practices to get a lower ABV beer. I find that yeast selection will have more of an impact on sweet character of a beer than mash temperature.

 

[Dland]

Assuming you are making beer, rather than some other wonderful fermented product:

If you want it sweet, with low ABV, best bet is to mash at high temps and use a light grain bill, or whatever your source of sugar...

Not saying what another approach would not work, but you'd basically be arresting the "digestion" of sugars.

As mentioned above, could easily lead to bottle bombs & keg gushers if them yeasts get going again,, and you know they will if they can ;}

 

[JSetzer]

Arrested Fermentation is the term that I have heard and mostly for brewing very low to no alcohol beers. On a homebrew level it would probably be hard to manage and I would be worried about potential off flavors. The general cycle of yeast is that during fermentation they can produce undesirable compounds. As they run out of sugar and prepare for dormancy, they will absorb the undesirable compounds.

Note that my organic chemistry game is pretty weak, so I am sure the above description is probably not 100% accurate. But pretty much every book on brewing will talk about a clean up stage (or a diacyl rest) to reduce off flavors.

You could potentially back sweeten (add sugars) into the keg, or follow other practices to get a lower ABV beer. I find that yeast selection will have more of an impact on sweet character of a beer than mash temperature.

Thanks! I figured as much as I’d never heard of anyone really taking that approach.

 

[JSetzer]

Assuming you are making beer, rather than some other wonderful fermented product:

If you want it sweet, with low ABV, best bet is to mash at high temps and use a light grain bill, or whatever your source of sugar...

Not saying what another approach would not work, but you'd basically be arresting the "digestion" of sugars.

As mentioned above, could easily lead to bottle bombs & keg gushers if them yeasts get going again,, and you know they will if they can ;}

Low mash temp then. Thank you. I’m not particularly going down a low ABV rabbit hole yet, I was just wondering if the process had any merit. Thanks for the response. I’m learning a ton on this forum!

 

[IslandLizard]

Not sure if this would work...

If you cold crash your unfinished beer very thoroughly to sediment all yeast, then rack to a keg without transferring any of that precipitated yeast, then sorbate your beer, you can probably curb refermentation. Sorbate in larger quantities also adds some additional sweetness.

Some people are sensitive to sorbate, so put a warning on your tap. Same when using lactose where not expected.

 

[Dland]

Low mash temp then. Thank you. I’m not particularly going down a low ABV rabbit hole yet, I was just wondering if the process had any merit. Thanks for the response. I’m learning a ton on this forum!

You want higher mash temp for sweeter beer. as mentioned in post 6. Maybe some kind soul w some will post the chart w temps for alpha & beta amilasies(sp?).

Of course you can have the best of both worlds w a semi dry but malty beer, but you did not ask about..never mind {;

 

[IslandLizard]

Maybe some kind soul w some will post the chart w temps for alpha & beta amilasies(sp?).

 

[JSetzer]

Not sure if this would work...

If you cold crash your unfinished beer very thoroughly to sediment all yeast, then rack to a keg without transferring any of that precipitated yeast, then sorbate your beer, you can probably curb refermentation. Sorbate in larger quantities also adds some additional sweetness.

Some people are sensitive to sorbate, so put a warning on your tap. Same when using lactose where not expected.

That’s interesting….I may have to try a small batch and see how that comes out.

 

[Drewch]

Arrested fermentation is done more in the wine world.

The gist is, as mentioned above, chill to near freezing and add sulfites.

The devil, however, is in the details. You could dig around in the wine forums; there may be more info out there.

https://winemakermag.com/article/stopping-fermentation

 

[Gnomebrewer]

If you want to leave behind some sweetness, use a lower attenuating yeast. Some English strains in particular drop out early leaving some residual sugars. This leads to a lot sweeter tasting beer than one with a high FG from mashing higher.
For example, if you have a 1.050 beer mashed high and fermented with a chico yeast, you might get a 1.015FG. You could alternatively mash low but use a lower attenuating English strain to finish at 1.015. The second option will taste sweeter. This is because the longer chain (unfermentable) carbohydrates created by the high mash temp don't taste as sweet as the fermentable sugars that the lazy yeast leave behind.

 

[JSetzer]

Thanks Gnomebrewer!