Attenuation with non fermentables
Attenuation with non fermentables
Hello everyone. I have a question. I have brewed a raspberry and vanilla smoothy ipa. The question is about attenuation when you have added non fermentables to the boil. I added 840g of lactose to the boil which i understand will increase the gravity but will be non fermentable by the yeast. How does this affect the final gravity with regards the ideal attenuation of the yeast?
The OG was 1.055 and the estimated OG is 1.012
It is currently sitting at 1.020 which is an attenuation of 64% if i understand it correctly.
If you are adding a non fermentable, how are you supposed to predict the FG based on the attenuation?
Would adding another packet of rehydrated S04 bring it down a bit more do you think?
The OG was 1.055 and the estimated OG is 1.012
It is currently sitting at 1.020 which is an attenuation of 64% if i understand it correctly.
If you are adding a non fermentable, how are you supposed to predict the FG based on the attenuation?
Would adding another packet of rehydrated S04 bring it down a bit more do you think?
 Eric
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Re: Attenuation with non fermentables
Without knowing the volume involved it is not possible to adjust for the lactose addition
For all practical purposes, a litre of your wort with gravity of 1055 might be assumed to have 55g of sugars including the added lactose.
Divide your 840g addition by the volume of wort in your FV plus the volume of any wort left in the boiler to dead space and hops to get the weight of lactose per litre. Take this from the OG and FG to determine the other sugars.
For all practical purposes, a litre of your wort with gravity of 1055 might be assumed to have 55g of sugars including the added lactose.
Divide your 840g addition by the volume of wort in your FV plus the volume of any wort left in the boiler to dead space and hops to get the weight of lactose per litre. Take this from the OG and FG to determine the other sugars.
Without patience, life becomes difficult and the sooner it's finished, the better.
Re: Attenuation with non fermentables
Eric  I totally concur with the principle of your suggestion, but are you saying that, as a basis, 55g of sugar would add 55 SG points to a litre? I must be missing something... wouldn't it be more like 130g, or maybe 190g of lactose?Eric wrote: ↑Thu Nov 08, 2018 9:34 pmWithout knowing the volume involved it is not possible to adjust for the lactose addition
For all practical purposes, a litre of your wort with gravity of 1055 might be assumed to have 55g of sugars including the added lactose.
Divide your 840g addition by the volume of wort in your FV plus the volume of any wort left in the boiler to dead space and hops to get the weight of lactose per litre. Take this from the OG and FG to determine the other sugars.
You're a font of knowledge, so I assume I'm not getting you, but I can't see what else you mean and have to ask!
Busy in the Summer House Brewery
Re: Attenuation with non fermentables
Thanks for the reply. So i have 24 litres in my fermenter, i had 2 litres left in the boiler. So 840/26 = 32.31.Eric wrote: ↑Thu Nov 08, 2018 9:34 pmWithout knowing the volume involved it is not possible to adjust for the lactose addition
For all practical purposes, a litre of your wort with gravity of 1055 might be assumed to have 55g of sugars including the added lactose.
Divide your 840g addition by the volume of wort in your FV plus the volume of any wort left in the boiler to dead space and hops to get the weight of lactose per litre. Take this from the OG and FG to determine the other sugars.
So 32.31g of lactose per litre. I am not sure what to do next with this calculation.
Re: Attenuation with non fermentables
840g of lactose in 26L would have added roughly 9 points to the OG (and to the FG, seeing as it doesn't ferment). It's quite a lot of lactose for the batch size, and you might expect it to finish in the mid or high teens, SG wise.
Busy in the Summer House Brewery
Re: Attenuation with non fermentables
The recipe and grainfather app suggested a OG of 1.057 and FG of 1.014. The measured OG was 1.055 and its now sat at 1.020 for a couple of days. The grainfather app looks like it takes the non fermentable lactose into account regards the gravity. If i remove it the OG and FG go down. If i add more lactose the OG and FG go up. I have given the wort a small swirl (difficult to do in a chronical) and also added another rehydrated packet of S04. This has had no affect as its still sat at 1.020. So i guess it has actually finsished at that FG. Time to add the raspberries and vanilla pods followed by the large amount of dry hops

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Re: Attenuation with non fermentables
Used to brew with s04 a lot and it's not a great attenuator unless you mash low and warm it right up at the end. It loves to carry on in the packaging too so if you're looking for a lower FG, add some us05 or Nottingham and it'll chew up the maltotriose.
Re: Attenuation with non fermentables
Thanks for that, i have some us05 in the fridge so may make a decision and add it.Robwalkeragain wrote: ↑Fri Nov 09, 2018 12:48 pmUsed to brew with s04 a lot and it's not a great attenuator unless you mash low and warm it right up at the end. It loves to carry on in the packaging too so if you're looking for a lower FG, add some us05 or Nottingham and it'll chew up the maltotriose.
 Eric
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Re: Attenuation with non fermentables
Thanks for the correction, absolute bollocks from me. My only excuse can be age and lack of concentration.MTW wrote: ↑Fri Nov 09, 2018 12:14 amEric  I totally concur with the principle of your suggestion, but are you saying that, as a basis, 55g of sugar would add 55 SG points to a litre? I must be missing something... wouldn't it be more like 130g, or maybe 190g of lactose?Eric wrote: ↑Thu Nov 08, 2018 9:34 pmWithout knowing the volume involved it is not possible to adjust for the lactose addition
For all practical purposes, a litre of your wort with gravity of 1055 might be assumed to have 55g of sugars including the added lactose.
Divide your 840g addition by the volume of wort in your FV plus the volume of any wort left in the boiler to dead space and hops to get the weight of lactose per litre. Take this from the OG and FG to determine the other sugars.
You're a font of knowledge, so I assume I'm not getting you, but I can't see what else you mean and have to ask!
I was trying to do a rule of thumb calculation (For all practical purposes as my opening) and totally fouled up an attempt to show no need a computer and software for such calculations using litre degrees per kilogram which I didn't. End of a poor excuse and I'll keep quiet as you've kindly done the sums and provided the answer
Without patience, life becomes difficult and the sooner it's finished, the better.
Re: Attenuation with non fermentables
Haha  Definitely nothing to do with the beer then Eric. Never blame the beer; that's my rule.Eric wrote: ↑Fri Nov 09, 2018 3:18 pmThanks for the correction, absolute bollocks from me. My only excuse can be age and lack of concentrationMTW wrote: ↑Fri Nov 09, 2018 12:14 amEric  I totally concur with the principle of your suggestion, but are you saying that, as a basis, 55g of sugar would add 55 SG points to a litre? I must be missing something... wouldn't it be more like 130g, or maybe 190g of lactose?Eric wrote: ↑Thu Nov 08, 2018 9:34 pmWithout knowing the volume involved it is not possible to adjust for the lactose addition
For all practical purposes, a litre of your wort with gravity of 1055 might be assumed to have 55g of sugars including the added lactose.
Divide your 840g addition by the volume of wort in your FV plus the volume of any wort left in the boiler to dead space and hops to get the weight of lactose per litre. Take this from the OG and FG to determine the other sugars.
You're a font of knowledge, so I assume I'm not getting you, but I can't see what else you mean and have to ask!
I was trying to do a rule of thumb calculation (For all practical purposes as my opening) and totally fouled up an attempt to show no need a computer and software for such calculations using litre degrees per kilogram which I didn't. End of a poor excuse and I'll keep quiet as you've kindly done the sums and provided the answer
Busy in the Summer House Brewery

 Piss Artist
 Posts: 269
 Joined: Tue Jun 05, 2018 9:19 am
Re: Attenuation with non fermentables
Quickest reference for me is always the side of your hydrometer, got a decent sugar per L meter thing on there.
Re: Attenuation with non fermentables
Not to be forgotten, I guess!Robwalkeragain wrote: ↑Sat Nov 10, 2018 12:42 pmQuickest reference for me is always the side of your hydrometer, got a decent sugar per L meter thing on there.
My quick reference is
18g (cane/beet) sugar per litre = 1% ABV = 7.4 SG points
It takes around a third more lactose than sucrose to hit the same SG.
All approximate, but easily switched around depending what's needed.
Busy in the Summer House Brewery
Re: Attenuation with non fermentables
Not sure i understand where this thread has gone regards the original question or it might just be me.
As i know understand it then it seems like i take the OG apply the attenuation percentage to get the predicted FG then add a few points on
In all honesty it was just the fact the FG ended alot higher than i am used to. I understand its to do with the lactose being an unfermentable but the software seemed to take that into acount to gave a predicted FG. It seems then the software is a bit off when it comes to lactose.
A few others that have brewed this recipe have also found the FG to be around 1.020 instead of the predicted 1.014 given by the recipe and software.
As i know understand it then it seems like i take the OG apply the attenuation percentage to get the predicted FG then add a few points on
In all honesty it was just the fact the FG ended alot higher than i am used to. I understand its to do with the lactose being an unfermentable but the software seemed to take that into acount to gave a predicted FG. It seems then the software is a bit off when it comes to lactose.
A few others that have brewed this recipe have also found the FG to be around 1.020 instead of the predicted 1.014 given by the recipe and software.
Re: Attenuation with non fermentables
I think the original question ["If you are adding a non fermentable, how are you supposed to predict the FG based on the attenuation?"] has been answered, though if it helps to phrase it differently: you can calculate the OG and FG of the underlying beer (minus the unfermentables) and apply whatever method you would normally, in estimating the attenuation of that. That may be with software. Then add back any SG points that will have come from the unfermentables. You can, as you've mentioned, just take the lactose out of the recipe on your software and add it back again, to see what the underlying beer would have yielded.chefgage wrote: ↑Sat Nov 10, 2018 6:14 pmNot sure i understand where this thread has gone regards the original question or it might just be me.
As i know understand it then it seems like i take the OG apply the attenuation percentage to get the predicted FG then add a few points on
In all honesty it was just the fact the FG ended alot higher than i am used to. I understand its to do with the lactose being an unfermentable but the software seemed to take that into acount to gave a predicted FG. It seems then the software is a bit off when it comes to lactose.
A few others that have brewed this recipe have also found the FG to be around 1.020 instead of the predicted 1.014 given by the recipe and software.
In my last post, I went on to give the underlying rule of thumb I use in working out the additional SG points from the lactose. I don't see any deviation in the direction of the thread there, but I hope that tidies it up in regard to your main question.
A worked example. I will use totally different figures to avoid confusion with your beer:
I measure my OG on brewday as 1.045 with 100g lactose in it. The total wort in the kettle before draining it was 10L.
I know (from my quick reference in previous post) that 18g of sugar per litre would have contributed 7.4 points to that OG, and that a third more lactose would be required to add the same, ie 24g/l. But I only added 10g per litre (100g/10L).
10/24=0.42
0.42*7.4=3.1
I have calculated that the lactose contributed around 3.1 points to that OG of 1.045. Without the lactose, I would have an OG of around 1.042. If I expect 75% AA from my yeast on that, then I could expect the FG of the 'underlying beer' to be 1.0101.011. Adding the 3 points back on gives you the expected FG with the lactose. That will give a higher FG than if I had simply applied my expected attenuation %age to the OG that had the lactose in it. In your beer, with such a high percentage of lactose in the bill, the difference would have been even more.
You also asked about whether adding some S04 would get it down further. If the estimate of FG is correct, then it's unlikely.
Busy in the Summer House Brewery
Re: Attenuation with non fermentables
Thanks for the detailed example. I understand it nowMTW wrote: ↑Sat Nov 10, 2018 7:02 pmI think the original question ["If you are adding a non fermentable, how are you supposed to predict the FG based on the attenuation?"] has been answered, though if it helps to phrase it differently: you can calculate the OG and FG of the underlying beer (minus the unfermentables) and apply whatever method you would normally, in estimating the attenuation of that. That may be with software. Then add back any SG points that will have come from the unfermentables. You can, as you've mentioned, just take the lactose out of the recipe on your software and add it back again, to see what the underlying beer would have yielded.chefgage wrote: ↑Sat Nov 10, 2018 6:14 pmNot sure i understand where this thread has gone regards the original question or it might just be me.
As i know understand it then it seems like i take the OG apply the attenuation percentage to get the predicted FG then add a few points on
In all honesty it was just the fact the FG ended alot higher than i am used to. I understand its to do with the lactose being an unfermentable but the software seemed to take that into acount to gave a predicted FG. It seems then the software is a bit off when it comes to lactose.
A few others that have brewed this recipe have also found the FG to be around 1.020 instead of the predicted 1.014 given by the recipe and software.
In my last post, I went on to give the underlying rule of thumb I use in working out the additional SG points from the lactose. I don't see any deviation in the direction of the thread there, but I hope that tidies it up in regard to your main question.
A worked example. I will use totally different figures to avoid confusion with your beer:
I measure my OG on brewday as 1.045 with 100g lactose in it. The total wort in the kettle before draining it was 10L.
I know (from my quick reference in previous post) that 18g of sugar per litre would have contributed 7.4 points to that OG, and that a third more lactose would be required to add the same, ie 24g/l. But I only added 10g per litre (100g/10L).
10/24=0.42
0.42*7.4=3.1
I have calculated that the lactose contributed around 3.1 points to that OG of 1.045. Without the lactose, I would have an OG of around 1.042. If I expect 75% AA from my yeast on that, then I could expect the FG of the 'underlying beer' to be 1.0101.011. Adding the 3 points back on gives you the expected FG with the lactose. That will give a higher FG than if I had simply applied my expected attenuation %age to the OG that had the lactose in it. In your beer, with such a high percentage of lactose in the bill, the difference would have been even more.
You also asked about whether adding some S04 would get it down further. If the estimate of FG is correct, then it's unlikely.