Sugar addition during fermentation : how much?

[beauvafr]

I have a brown bitter that seems to have finished at 1.018 in primary after about a week. It started at 1.050 so ABV is about 4.1%. Temp were 64f to 69F. I got 2 reading at 1.017 so it seems finished. Now I don't think it's enough so I just want to lower the FG by adding a bit of dextrose. But not too much, since I don't want this beer to be thin. It's an english ale!

I remember reading about a rule of thumbs for sugar addition in primary and gravity drop. Do you happen to know where I can find it?

 

[Calder]

I don't know what guide you are looking for.

Sugar will only bring you down a few points.

If you add 1.3 lbs of table sugar, it will increase your effective OG to 1.060 (20% from sugar), and probably lower the FG to 1.015 (assuming it is finished at 1.017).

 

[Yooper]

Maybe. Or, the FG won't drop at all. I mean, the sugar you add, say 5 points, will ferment out 5 points, and you'll still be at 1.017.

Adding more fermentables to it will increase the ABV, because they will ferment out and sugar is fully fermentable, but it won't magically make the unfermentables in the beer currently suddenly fermentable and lower the FG.

 

[Calder]

Maybe. Or, the FG won't drop at all. I mean, the sugar you add, say 5 points, will ferment out 5 points, and you'll still be at 1.017.

Adding more fermentables to it will increase the ABV, because they will ferment out and sugar is fully fermentable, but it won't magically make the unfermentables in the beer currently suddenly fermentable and lower the FG.

Simple sugars ferment out more than 100% (apparent attenuation). The additional alcohol lowers the overall gravity. All the unfermentable sugars are still there. You need to add a lot to the OG to get a little off the FG.

 

[beauvafr]

So.. would you do it?

 

[helibrewer]

I would leave it alone. If this was an AG beer I would look back at your notes and see if there is a need to adjust your mash schedule. You are a few points high on the FG but it's not ridiculously off.

 

[william_shakes_beer]

For next time, try mashing a few degrees lower to get a more fermentable wort.

 

[Yooper]

Simple sugars ferment out more than 100% (apparent attenuation). The additional alcohol lowers the overall gravity. All the unfermentable sugars are still there. You need to add a lot to the OG to get a little off the FG.

Oh, yes, I understand the concept- but the amount of extra alcohol created would be so small (one pound of sugar in 5 gallons would increase the OG by 9 points) which means less than a 1% ABV boost, which would be negligible in the FG reading.

 

[ArkotRamathorn]

If its a Belgian style and I don't need the color addition from a d-180 for example, I save the sugar additions for when its right near the end of high krausen. If no sugar in kettle I try and get my addition on a Belgian style between 10% and 15%.

Some styles like an IPA I have planned, I don't want to do the sugar additions until near the end of high krausen. A) for proper hop utilization in the boil kettle B) less initial stress on the yeast C) if I put it in right at the end of high krausen it'll re kick up the yeast I'll drive that gravity down a couple more points. Even if this IPA finishes like 1.015 after the sugar additions, it should still have that crisp dry mouth feel of a lower gravity beer.

I had a scotch ale that stopped at 1.030 and did a .5lb addition to try and drive it down further after upping temps and rousing. Annoyed that it still read 1.030 at bottling, but homebrew club president liked my scotch ale better than his own because it came out drier. So it may not physically drive your final gravity down for some yeasts, I had a BDSA that was stopping around 1.018 (1.085 starting) and after 1.5lbs of sugar (no kettle additions, all primary fermentation additions) it tumbled down to 1.010.