FG 1.000 and Unfermentable Sugars

[dmtaylor]

I've reached a point in my brewing knowledge where I'm confused about unfermentable/residual sugars...

For my last brew, a Belgian Blond, I mashed at 154 in order to try to create some residual/unfermentable sugars. The recipe software said I would hit 1.012 FG, but instead all the sugar fermented out and I hit 1.000. Not a huge problem to have -- my Blond became a Tripel! But I don't understand what happened to the unfermentable sugars?

The Belgian yeasts (I blended 3) were supposed to be moderately attenuative, but certainly not 100%.

Here are some factors that I think likely contributed to the 1.000, but I still don't understand what happened to the unfermentable sugars:

1. I tend to blend yeasts and it's very possible I overpitched. (I didn't use a pitching calculator.) Can overpitching alone cause 100% attenuation?

2. I mashed at 154, but for 90 minutes. The long mash likely created a more fermentable wort as the temp dropped a few degrees, but 100% fermentable?

3. I used a pound of table sugar to thin out the body and add ABV. (It was included in the recipe calculator.) I know sugar ferments out 100%, but again, what happened to the unfermentable sugars? Does sugar somehow accelerate fermentation so much that the yeast eats up the unfermentable sugar too?

Of course, I do know what to try next time, and I could do experiments: I could mash even higher, use less yeast, less sugar, and a shorter mash. But I want to understand what's going on, so I can better control my numbers. Thanks for any help you could provide.

I'm answering your questions without reading anybody else's responses yet.

1. Which yeasts? (Hopefully someone else already asked.) The specific strains matter a LOT. Some are probably diastaticus, hence your high attenuation. Pitch rate and overpitching does NOT matter AT ALL.

2. Your mash temperature of 154 F is not very hot. If you want low fermentability, try like 158 F. Or even 160 F. Mash TIME is the overriding factor anyway. If you had mashed for just 30 minutes instead of 90 minutes, huge difference in attenuation. Also, your 100% attenuation is specifically "apparent" attenuation, not real attenuation. In reality, there's still sugars left even at 1.000. If nearly all of the sugars actually fermented out, you would be left with a gravity closer to like 0.990. Yes, seriously.

3. The sugar definitely affected attenuation. There are still some unfermented sugars, as mentioned above in #2. Just not as much as you expected. Sugar doesn't boost the yeast or anything like that. They just see it and eat it all, up to their alcohol tolerance anyway, which in this case was apparently not reached for at least one of the three yeasts you used.

I think diastaticus was at play here. Diastaticus variant yeasts are well known for producing FG of 1.000-1.002. Belle Saison and Wyeast 3711 are the most famous of these. Yeast matters most.

Next time mash at around 156 F for just 30-40 minutes, and avoid diastaticus. You'll get a different result. But the diastaticus yeast is key. If you still have diastaticus in there, you'll still get about 1.002 no matter what the heck you do with mash time or temperature.

Now I'll read everybody else's answers, and add editorial comments as appropriate. Hope some of us are singing the same song already. Cheers.

 

[bracconiere]

Beersmith agrees that it should have finished at 1.013?

yes it did....or 1.012

 

[SRJHops]

I'm answering your questions without reading anybody else's responses yet.

1. Which yeasts? (Hopefully someone else already asked.) The specific strains matter a LOT. Some are probably diastaticus, hence your high attenuation. Pitch rate and overpitching does NOT matter AT ALL.

2. Your mash temperature of 154 F is not very hot. If you want low fermentability, try like 158 F. Or even 160 F. Mash TIME is the overriding factor anyway. If you had mashed for just 30 minutes instead of 90 minutes, huge difference in attenuation. Also, your 100% attenuation is specifically "apparent" attenuation, not real attenuation. In reality, there's still sugars left even at 1.000. If nearly all of the sugars actually fermented out, you would be left with a gravity closer to like 0.990. Yes, seriously.

3. The sugar definitely affected attenuation. There are still some unfermented sugars, as mentioned above in #2. Just not as much as you expected. Sugar doesn't boost the yeast or anything like that. They just see it and eat it all, up to their alcohol tolerance anyway, which in this case was apparently not reached for at least one of the three yeasts you used.

I think diastaticus was at play here. Diastaticus variant yeasts are well known for producing FG of 1.000-1.002. Belle Saison and Wyeast 3711 are the most famous of these. Yeast matters most.

Next time mash at around 156 F for just 30-40 minutes, and avoid diastaticus. You'll get a different result. But the diastaticus yeast is key. If you still have diastaticus in there, you'll still get about 1.002 no matter what the heck you do with mash time or temperature.

Now I'll read everybody else's answers, and add editorial comments as appropriate. Hope some of us are singing the same song already. Cheers.

No need to read the others - you are spot on! Actually glad you answered this way -- good to see it all put together. Thanks!

 

[SRJHops]

yes it did....or 1.012

I guess that means the recipe calculators aren't so good at diastaticus variant yeasts. (I'm not too proud to admit that I didn't even know that word before today.) Much appreciation to you all!

 

[dmtaylor]

Side question: Is Lactose broken down by the STA1 strains? Because I was thinking that adding some would help with OPs issue. Thanks

Nope, diastaticus yeasts cannot eat lactose. This is one option to increase FG if desired. About a half pound in 5 gallons can take the edge off a bit and add approximately 0.005.

 

[dmtaylor]

Here's the recipe. Thanks for your help. As you will see, the predicted FG was 1.013. I was trying to keep the ABV to under 7.5%.

https://www.brewersfriend.com/homebrew/recipe/view/1131988/blond
Love to see what Beersmith says. Also if I did anything wrong with the Brewer's Friend calculator...

Thanks for the recipe. All 3 of your yeasts are diastaticus. The "worst offender" could have been any of the 3, I'm not sure which one.

 

[dmtaylor]

I have a Tilt in there now, and it tends to be pretty accurate on the FG, not as good at OG. So I take OG with a refractometer, hydrometer, and the Tilt. OF COURSE I get three different readings! I tend to trust the hydrometer when push comes to shove.

Here's some stuff from me about the Tilt:

https://www.homebrewersassociation.org/forum/index.php?topic=32797.msg432694#msg432694
In particular:

" When yeast and hops are stuck to the Tilt, it will make the SG read lower than it really is. Don't be surprised when your FG ends up being 1.006 when you expected 1.012 or whatever. "

 

[SRJHops]

Here's some stuff from me about the Tilt:

https://www.homebrewersassociation.org/forum/index.php?topic=32797.msg432694#msg432694
In particular:

" When yeast and hops are stuck to the Tilt, it will make the SG read lower than it really is. Don't be surprised when your FG ends up being 1.006 when you expected 1.012 or whatever. "

Agreed. I do check with a hydrometer for the FINAL FG. I also got 1.000 on my last beer using the same 3 yeasts.

 

[SRJHops]

Thanks for the recipe. All 3 of your yeasts are diastaticus. The "worst offender" could have been any of the 3, I'm not sure which one.

What? Really? Sheesh. Are ALL Belgian yeasts diastaticus? I thought the offender was the Be-134 Saison yeast. The other two are just regular ol' Belgian yeasts...

 

[dmtaylor]

Agreed. I do check with a hydrometer for the FINAL FG. I also got 1.000 on my last beer.

If this has become a pattern where you are getting close to 1.000 for every beer... it might be a permanent "contamination" issue where diastaticus yeasts hide out in soft materials in your fermentation equipment, which can include hoses, stoppers, o-rings, buckets, etc. If this continues for many batches, it might be time to consider replacing all soft materials. I've had to do this a few times over the past 23 years when I started getting something off in my beers including super high attenuation.

 

[dmtaylor]

What? Really? Sheesh. Are ALL Belgian yeasts diastaticus?

Nope, not all. But many of them are. You just rolled the dice to the same number three times.

 

[SRJHops]

If this has become a pattern where you are getting close to 1.000 for every beer... it might be a permanent "contamination" issue where diastaticus yeasts hide out in soft materials in your fermentation equipment, which can include hoses, stoppers, o-rings, buckets, etc. If this continues for many batches, it might be time to consider replacing all soft materials. I've had to do this a few times over the past 23 years when I started getting something off in my beers including super high attenuation.

Oh, it was a Saison, and I won a contest with it. But that doesn't mean you are aren't right...

 

[dmtaylor]

Oh, it was a Saison, and I won a contest with it. But that doesn't mean you aren't right....

Sure, I'm not saying this is a bad thing. But if you brew some non-Belgian style where you expect an FG of like 1.013 but you still end up with 1.000, then red alert! Then it might be time to dedicate this equipment to only use it for saison-like styles, and nothing else.

 

[VikeMan]

Thanks for the recipe. All 3 of your yeasts are diastaticus. The "worst offender" could have been any of the 3, I'm not sure which one.

1214 and 3522 are diastaticus? That's news to me. And Wyeast doesn't mention it. Not saying your wrong, but what's your source?

 

[dmtaylor]

1214 and 3522 are diastaticus? That's news to me. And Wyeast doesn't mention it. Not saying your wrong, but what's your source?

My reference is me myself. I guess I shouldn't have been so bold to declare this, as I'm not 100% sure yet whether these have the STA1 gene. All I did was take a quick glance at my spreadsheets and noticed these have both given me 85% attenuation in past batches... which would seem to be consistent with a STA1 yeast... but understanding they might actually just be really crazy yeasts but don't actually have the gene. I will actually have to confirm later whether or not these are true STA1 yeast, I've got more data on a different computer. So, hold your breath for a bit, if it matters. Regardless.... these yeasts definitely will give very high attenuation, even if they're not officially "diastaticus". Very high.

 

[SRJHops]

Sure, I'm not saying this is a bad thing. But if you brew some non-Belgian style where you expect an FG of like 1.013 but you still end up with 1.000, then red alert! Then it might be time to dedicate this equipment to only use it for saison-like styles, and nothing else.

Yeah, it totally does have me wondering if I have some kind of "good" infection! I am totally Belgian right now, but maybe I will break down and go back to my old friend the NEIPA, which I brewed (the same recipe) over and over for two years!

 

[dmtaylor]

Turns out I was not quite right. I mean, although the attenuation of these yeasts is all quite high, Wyeast 3522 is in fact NOT diastaticus (STA1 negative).

Meanwhile, Wyeast 1214 is peculiar in that it is a hybrid yeast with S. kudriavzevii as part of its genetic makeup. I'm not sure if it's STA1 positive or not, but this is certainly something unusual. Reference: Brewing yeast family tree (Oct 2019 update) | Suregork Loves Beer
Actually, as part of the Beer2 clade where other diastaticus yeasts are located, it's quite likely to be a diastaticus.

 

[SRJHops]

Turns out I was not quite right. I mean, although the attenuation of these yeasts is all quite high, Wyeast 3522 is in fact NOT diastaticus (STA1 negative).

Meanwhile, Wyeast 1214 is peculiar in that it is a hybrid yeast with S. kudriavzevii as part of its genetic makeup. I'm not sure if it's STA1 positive or not, but this is certainly something unusual. Reference: Brewing yeast family tree (Oct 2019 update) | Suregork Loves Beer
Actually, as part of the Beer2 clade where other diastaticus yeasts are located, it's quite likely to be a diastaticus.

Thanks for the follow up. It's all good. I am now digging into diastaticus yeasts... It seems Saisons have the STA1+ gene -- not sure how common it is in other commercial yeasts. From what I can tell, not very common in yeasts we would purchase. It does seem to be common in wild yeast that can cause contamination.

I did brew a fruit sour in between the two 1.000 beers, and it did not attenuate down to 1.000. BUT it does seem like contamination of my brewing vessels should be of concern. Time to up my cleaning regimen!

 

[Birrofilo]

I made a Saison the other month that was also 1.000, and it had a hint of sweetness. So I think FG is only one measure of the perceived sweetness....

Perceived sweetness depends on many factors. Supposing all simple sugars have been converted, which is normal unless the yeast reached the alcohol toleration limit before clearing its plate, dextrins remain which can be perceived as sweet (or as more or less sweet) by different palates. "Maltiness" in general is perceived as sweet by many, as myself, but not by all, and is mainly dextrins, but this sweetness can be masked by sourness or bitterness, again depending on single persons.

Although everybody will agree that a beverage is clearly sweet or is clearly bitter, when one is in the limelight, e.g. hints of sweetness, hints of bitterness, mixing sweetness and bitterness, sour-bitter, sour-sweet etc. persons can perceive things in different ways.

As said by others, a density of 1, giving the presence of alcohol which has a density less than 1, means that the rest of the beer has a density higher than 1, which indicates residual "sugars" present (dextrins normally) and that might give a "sweet" beer or not depending on sourness, bitterness, and palate.

 

[postalroger]

I recently brewed a saison with Mangrove Jack’s M29 French Saison yeast which went down to 1.000.
On a different note, you mentioned that your Tilt wasn’t as reliable for OG readings as for FG readings. I’ve had the same experience as well, mine is consistently 6-10 points lower than readings with a refractometer or hydrometer for OG.
FG readings usually are very similar.

 

[SRJHops]

I recently brewed a saison with Mangrove Jack’s M29 French Saison yeast which went down to 1.000.
On a different note, you mentioned that your Tilt wasn’t as reliable for OG readings as for FG readings. I’ve had the same experience as well, mine is consistently 6-10 points lower than readings with a refractometer or hydrometer for OG.
FG readings usually are very similar.

Yeah, I do really like having a Tilt, so I can see when fermentation gets going, watch the SG drop, and know when fermentation has ended. But my readings are like yours... For some reason it really struggles with OG, but unless there is gunk on it, it usually gets the FG pretty spot on. But I've learned to always use the hydrometer to double-check...

 

[SRJHops]

Perceived sweetness depends on many factors. Supposing all simple sugars have been converted, which is normal unless the yeast reached the alcohol toleration limit before clearing its plate, dextrins remain which can be perceived as sweet (or as more or less sweet) by different palates. "Maltiness" in general is perceived as sweet by many, as myself, but not by all, and is mainly dextrins, but this sweetness can be masked by sourness or bitterness, again depending on single persons.

Although everybody will agree that a beverage is clearly sweet or is clearly bitter, when one is in the limelight, e.g. hints of sweetness, hints of bitterness, mixing sweetness and bitterness, sour-bitter, sour-sweet etc. persons can perceive things in different ways.

As said by others, a density of 1, giving the presence of alcohol which has a density less than 1, means that the rest of the beer has a density higher than 1, which indicates residual "sugars" present (dextrins normally) and that might give a "sweet" beer or not depending on sourness, bitterness, and palate.

Thanks. Yeah, I have to wonder how much adding 5 or even 10 points really matters. Say I end at 1.000, but wanted to be at 1.010. I could add lactose or non-fermentable sugar, but not even sure it would be perceived.

I recently read a Brulosophy where they were testing this, and if I recall, tasters couldn't discern between beers with a 9 point difference in FG. So you have to wonder how much I would have to raise the FG to really make it noticeable.... I have to believe if I went from 1.000 to 1.020 there would be a difference.

On that note, I think I've crossed another level of beer geekiness, because now I often get out the hydrometer to test the commercial beers I drink. I've been interested in seeing the big SG differences between the alco-pop fruit lambics and the oude ones...

 

[Beermeister32]

Turns out I was not quite right. I mean, although the attenuation of these yeasts is all quite high, Wyeast 3522 is in fact NOT diastaticus (STA1 negative).

Meanwhile, Wyeast 1214 is peculiar in that it is a hybrid yeast with S. kudriavzevii as part of its genetic makeup. I'm not sure if it's STA1 positive or not, but this is certainly something unusual. Reference: Brewing yeast family tree (Oct 2019 update) | Suregork Loves Beer
Actually, as part of the Beer2 clade where other diastaticus yeasts are located, it's quite likely to be a diastaticus.

I was looking at the most recent 2019 yeast family tree. I'm a bit confused, shouldn't there be a yeast number at the point where the black dots are? Would indicate to me anyway that a certain yeast evolved from another one. Or are they put adjacent two each other because the originating yeast (for two adjacent yeasts) are not known, but are close enough to show a kinship to each other? I don't see any that show the derivative yeast strains. Thanks.

 

[VikeMan]

I was looking at the most recent 2019 yeast family tree. I'm a bit confused, shouldn't there be a yeast number at the point where the black dots are? Would indicate to me anyway that a certain yeast evolved from another one. Or are they put adjacent two each other because the originating yeast (for two adjacent yeasts) are not known, but are close enough to show a kinship to each other? I don't see any that show the derivative yeast strains. Thanks.

Those dots represent an (unknown) common ancestor. I don't know exactly how Suregork built his tree, but the lengths of the branches leading back to nodes (with a dot in the case of Suregork's tree) are typically a rough indication of how distant the ancestor was, in this case perhaps based on the accumulation of mutations (which happen at roughly predictable rates).

 

[Beermeister32]

Makes sense.

 

[dmtaylor]

Those dots represent an (unknown) common ancestor. I don't know exactly how Suregork built his tree, but the lengths of the branches leading back to nodes (with a dot in the case of Suregork's tree) are typically a rough indication of how distant the ancestor was, in this case perhaps based on the accumulation of mutations (which happen at roughly predictable rates).

Exactly right.

 

[SRJHops]

I stumbled upon this old thread... That blond that attenuated to 1.000? I entered it in a competition and it won first place!

It's funny looking back on this old thread. Now I pretty much use Saison yeast in all my Belgians. I made a golden strong today and pitched 3522 and 3711.