Is 20 percent dextrose (added post fermentation) too much for a dry wc IPA?

[tyrub42]

Hi everyone,

Gonna be totally honest this is just me trying to find ways to not make a second yeast starter, but I frequently use 10 percent dex in wc IPAs and enjoy it. I looked around but it seems like the dangers of too much dextrose are mostly when it's added before the main fermentation. If I add it all to the fermenter on day 3-4 when fermentation is winding up, is there any danger? Seems like it should be fine, but figured I'd ask here. Thanks!

 

[lumpher]

You can use 20%, but be very careful about your ferm temps. Many Belgians use close to 20%. Add when ferm is winding down, using simple sugar.

 

[Beerstein]

Or add it in small doses. I accidentally used 10% a while back. That was plenty to dry it out. Didn't taste fusel-ly, but had a definite buzz factor.

 

[AlexKay]

I use 50% honey in my braggots. I know there are theoretically problems, but I’ve never come across them. Worth trying to see if it works for you!

 

[tyrub42]

Perfect, thanks everyone!

 

[Miraculix]

Just curious, you did remove some of the base malt for it, correct? Otherwise it wouldn't thin the beer out but only add more abv on top.

 

[McMullan]

I'd add it before or after fermentation. Simple sugars down regulate metabolism of more complex sugars and it's probably best not to mess with the yeast's natural progression from metabolising simple to complex sugars. If added at the end it's kind of a bit like repitching the yeast. The only thing potentially wrong is reactivating yeast in a potentially nutrient deficient media. I'd add some yeast nutrients with the dextrose, just in case.

 

[tyrub42]

Just curious, you did remove some of the base malt for it, correct? Otherwise it wouldn't thin the beer out but only add more abv on top.

Yep of course. It basically went into the fermenter as a session IPA and will come out a 6.5 percent beer ending somewhere around 1.010

 

[tyrub42]

I'd add it before or after fermentation. Simple sugars down regulate metabolism of more complex sugars and it's probably best not to mess with the yeast's natural progression from metabolising simple to complex sugars. If added at the end it's kind of a bit like repitching the yeast. The only thing potentially wrong is reactivating yeast in a potentially nutrient deficient media. I'd add some yeast nutrients with the dextrose, just in case.

All of this is true except, to the best of my current understanding, this much dextrose would never be a good idea before fermentation, as it can produce yeast that are less attenuating of longer chain sugars than they would be otherwise. So basically exactly what you pointed out as a potential problem of adding it mid-fermentation except pre-fermentation would be the worst possible time, wouldn't it?

Otoh I've actually had really good luck restarting stuck fermentations in big beers by adding a vitality starter of fresh yeast combined with a shot of dextrose equivalent to about 5 percent of the grain bill. Not sure the mechanism behind it, but it's worked every time a friend or I have tried it, and frequently gotten the fg down to target from up to 10-15 points above

 

[McMullan]

Nope, it (fermentables) all gets processed as simple sugar by the yeast cells at the end of the day. Think about it. The biology. I sometimes use over 30% invert in a low gravity mild recipe with excellent results.

 

[tyrub42]

Nope, it (fermentables) all gets processed as simple sugar by the yeast cells at the end of the day. Think about it. The biology. I sometimes use over 30% invert in a low gravity mild recipe with excellent results.

I'm not saying you're wrong but the general consensus disagrees with you. The general consensus has been wrong plenty of times, but logically it does make sense. Fermentables do not all get processed by yeast cells. Different strains will consume more or less of them, and this is dependent on how difficult specific carbohydrates are to metabolize. Every yeast strain will consume 100 percent of simple sugars like dextrose for example, but maltriose or other malt-derived carbohydrates will not get completely fermented, which is why finishing gravities end up higher than 1.000 (or the sub-1.000 equivalent when accounting for abv). The logic behind not adding more than a specific amount of sugar pre-fermentation (not sure of the specifics, but I think 10 percent is pretty much agreed to be safe. Not sure what the upper limit is supposed to be), is that yeast will of course ferment the simplest sugars first, and they reproduce during this time. If they have too much ultra-simple carbohydrates, later generations could get 'lazy' about fermenting longer chains, leaving a beer that doesn't ferment as well as it's supposed to.

Is this all BS? I honestly can't say 100 percent, but it's the biggest reason why I wanted to wait until fermentation was done before adding dextrose, just in case.

 

[McMullan]

Then the 'general consensus' is full of it

 

[Miraculix]

I'm not saying you're wrong but the general consensus disagrees with you. The general consensus has been wrong plenty of times, but logically it does make sense. Fermentables do not all get processed by yeast cells. Different strains will consume more or less of them, and this is dependent on how difficult specific carbohydrates are to metabolize. Every yeast strain will consume 100 percent of simple sugars like dextrose for example, but maltriose or other malt-derived carbohydrates will not get completely fermented, which is why finishing gravities end up higher than 1.000 (or the sub-1.000 equivalent when accounting for abv). The logic behind not adding more than a specific amount of sugar pre-fermentation (not sure of the specifics, but I think 10 percent is pretty much agreed to be safe. Not sure what the upper limit is supposed to be), is that yeast will of course ferment the simplest sugars first, and they reproduce during this time. If they have too much ultra-simple carbohydrates, later generations could get 'lazy' about fermenting longer chains, leaving a beer that doesn't ferment as well as it's supposed to.

Is this all BS? I honestly can't say 100 percent, but it's the biggest reason why I wanted to wait until fermentation was done before adding dextrose, just in case.

I think what he wanted to say is that the yeast turns all longer sugars into simple ones at the end of the day, before metabolizing them. Some do it with the excretion of enzymes, looking at you diastatic strains, and some might transfer longer sugars into the cell and let the enzymes do their work there. Long story short, it takes up more energy than just directly munching on glucose. Either transferring the longer sugars actively through the cell membrane, or producing and excreting enzymes. It all uses up energy.

So it's in the yeast's best interest to eat all the available short sugars first, before starting the heavy lifting with the longer ones.

If yeasts might have problems to "go back" from shorter to longer sugars, I cannot say.

But what I read is that the glucose can be used to fuel the yeast to enable it to metabolize the longer sugars. Your anecdote with the repitching fresh yeast with dextrose to restart a stuck fermentation seems to support this.

 

[tyrub42]

Then the 'general consensus' is full of it

Definitely wouldn't be the first time (I still hear people talk about bottle conditioning scrubbing all the o2 from beers, so no need to purge your IPA bottles before/after filling). Thanks!

 

[tyrub42]

I think what he wanted to say is that the yeast turns all longer sugars into simple ones at the end of the day, before metabolizing them. Some do it with the excretion of enzymes, looking at you diastatic strains, and some might transfer longer sugars into the cell and let the enzymes do their work there. Long story short, it takes up more energy than just directly munching on glucose. Either transferring the longer sugars actively through the cell membrane, or producing and excreting enzymes. It all uses up energy.

So it's in the yeast's best interest to eat all the available short sugars first, before starting the heavy lifting with the longer ones.

If yeasts might have problems to "go back" from shorter to longer sugars, I cannot say.

But what I read is that the glucose can be used to fuel the yeast to enable it to metabolize the longer sugars. Your anecdote with the repitching fresh yeast with dextrose to restart a stuck fermentation seems to support this.

Very cool, thanks!

Do you feel that the idea that too much simple sugar added to a recipe can result in lower attenuation is completely untrue? No experience with it personally (I started with AG so I'll almost never add more than 10 percent dextrose to anything, and this is my first experience going up to about 20). Thanks!

 

[TLaffey]

I have no experience with Belgian brews (WC IPA all the way!) so the idea of adding sugar at the end of fermentation is new to me. IPA recipes I've seen/used seem to generally call for sugar, if used, to be added in the boil--my practice is about 5-10 minutes before the end of the boil. As to percentages, I note that the publicly available Pliny the Elder recipe uses 4.8% dextrose. As Pliny is lighter body and somewhat boozy, I can only imagine what you'd get with 10-20%!

Pliny the Elder with Amarillo? (post #16)
https://www.bertusbrewery.com/2015/10/pliny-elder-40.html

 

[Miraculix]

Very cool, thanks!

Do you feel that the idea that too much simple sugar added to a recipe can result in lower attenuation is completely untrue? No experience with it personally (I started with AG so I'll almost never add more than 10 percent dextrose to anything, and this is my first experience going up to about 20). Thanks!

I wouldn`t say that it is untrue, I have honestly no idea about yeast metabolism. All I know is that the yeast goes through the available sugars one by one, starting with the shortest. I do not know what happens if you bring in another round of glucose in the middle of fermentation. Both would be possible from my point of view, fueling the yeasties to ferment even more longer sugars, or spoiling them so that they do not touch any more longer ones afterwards.. who knows?

Adding it after fermentation finished is obviously the safest route, if you ask me. But if it is really necessary? I have no idea. I usually also add every simpel sugar at the end of the boil.

 

[tyrub42]

I have no experience with Belgian brews (WC IPA all the way!) so the idea of adding sugar at the end of fermentation is new to me. IPA recipes I've seen/used seem to generally call for sugar, if used, to be added in the boil--my practice is about 5-10 minutes before the end of the boil. As to percentages, I note that the publicly available Pliny the Elder recipe uses 4.8% dextrose. As Pliny is lighter body and somewhat boozy, I can only imagine what you'd get with 10-20%!

Pliny the Elder with Amarillo? (post #16)
https://www.bertusbrewery.com/2015/10/pliny-elder-40.html

It kind of depends on how you build the recipe. For example you could get a beer to finish at 1.005 without any simple sugars if I mash low and for a long time, but you could also design a recipe with lots of simple sugars added that still finishes relatively high depending on mash temp, mash length, yeast, etc. This beer will finish around 1.010 if all goes according to plan