Something different about this US-05 fermentation?

[DVCNick]

I've brewed plenty of IPA style beers with US-05, and they always finish in the 1.010 to 1.012ish range depending.

The one I just kegged is not an exact repeat of a recipe I've done before, but the grains are close enough, mostly 2 row with a little bit of pilsner and crystal malt.

This one also had a pound of corn sugar added to the boil.

Also, I missed my intended 152 mash temp pretty high, it was more like 155. I've always read this leads to a less fermentable wort.

Everything looked normal except this one finished at 1.008 or less, maybe 1.007 depending on how hard you stare at the hydrometer.

Does this sound strange, or within normal variation? OG was 1.064.

 

[Ralphie0523]

I would say the pound of corn sugar is probably the difference. This will completely ferment whereas converted sugars will always have some amount that doesn’t convert to a fermentable sugar. The difference between 152 and 155 isn’t a whole lot, but the corn sugar being 100% fermentable sure does make a difference. Not strange given the information. Unless I have misinterpreted something.

 

[cubalz]

Your FG would have been much lower if you didn't accidentally mash too high. Regardless, the sucrose is the root cause to the differing final gravity.

 

[DVCNick]

Gotcha.
A certain percent of the sugar contribution being 100% fermentable definitely makes sense on why the FG would be lower than a similar OG wort that was all from grain.. thanks.

 

[Mer-man]

Your FG would have been much lower if you didn't accidentally mash too high. Regardless, the sucrose is the root cause to the differing final gravity.

With the enzyme-packed modern 2-row, your mash temp is not going to make much of a difference to fermentability. The only way you can adjust fermentability is mashing very high and for very short duration (like 15 minutes). That would essentially deactivate the beta-amylase and only give you alpha to work with.

1.007 is not a surprising FG for 2-row and US-05, assuming you did 60min mash.

The DEXTROSE (that's what corn sugar is) will not change your FG because it is completely fermentable, compared to malt that always has a percentage of non-fermentable sugars.

It only seems like it over-attenuated because that dextrose bumped your OG from something in the 1.050 range - and when you discount the extra points (that will ferment completely), again 1.007 is not unreasonable for that grist.

Additionally: if you want to see the impact of mash temps and time, try brewing with European malts (Weyermann, Dingemann, Castle, etc.), which are not made for converting 50% unmalted grist.

 

[bracconiere]

depending on how hard you stare at the hydrometer.

and spin, and spin, still hoping for the SG.......i'd say it was the sugar....you could play with vintometers, and refractomer-hydrometer, comparisons to try and find out......

 

[RPh_Guy]

The DEXTROSE (that's what corn sugar is) will not change your FG because it is completely fermentable....

Dextrose lowers the FG however you look at it because the resulting ethanol is less dense than water.

 

[Mer-man]

Dextrose lowers the FG however you look at it because the resulting ethanol is less dense than water.

Only relative to grain sugars, which is my point.

 

[RPh_Guy]

Only relative to grain sugars, which is my point.

It's not relative, it's absolute.

If you have a 1.040 wort (or must) for example, adding sugar to it will always decrease the FG if all of it ferments.

Adding 10 gravity points of sugar will lower the FG by approximately 3 points.