Fg often low

[Mothman]

I'm fairly new to brewing, about 8 or 9 batches in, I do all grain BIAB.

I find that I am often somewhat low in FG.

As an example my current brew was predicted via Beersmith to end at 1.017 (includes some lactose) and as of today, I think it's done, is's at 1.014. I'm commonly a few points lower than beersmith predicts.

I'm fairly confident in my mash temperature, I've tested with very close temperature (within a degree F) with 3 different thermometers.

This brew is using US05 fermented at 64F for a few days then up to 68F and has been held there.

For those with more experience, is this anything you would concern yourself with?

My current brew called for a 154F mash... Would you try mashing a couple degrees higher? Or is a difference of, say, 3 or 4 points in FG really not noticeable anyways?

 

[GoeHaarden]

You have to remember that Beersmith, although a great program which I use as well, isn't always going to be dead on and it cannot account for every variable of everyone's brewing...

IMO, I don't worry about a few points...does it taste good?

 

[SEndorf]

If your consistently off by a set factor, Beersmith needs to be adjusted via brewhouse efficiency. There are an abundance of tutorials and videos on this.

 

[Mothman]

IMO, I don't worry about a few points...does it taste good?

Seems to. I'm not great at judging flavor in uncarbonated beer, but the gravity sample tasted OK.

And my previous batches have been good to very good.

Might be more a matter of me just trying to understand... With a part of me also somewhat bothered by possibly drying my beers out more than intended.

But I'm not sure if a few gravity points are even noticeable in the final product.

 

[Mothman]

If your consistently off by a set factor, Beersmith needs to be adjusted via brewhouse efficiency. There are an abundance of tutorials and videos on this.

It seems fairly consistent.

But...Brewhouse efficiency impacts FG predictions in Beersmith?

The way I understood it, OG and volume into the fermenter is what figures into Brewhouse efficiency?

 

[doug293cz]

It seems fairly consistent.

But...Brewhouse efficiency impacts FG predictions in Beersmith?

The way I understood it, OG and volume into the fermenter is what figures into Brewhouse efficiency?

I don't think so. BeerSmith uses rules of thumb, along with data on yeasts' typical attenuation data to estimate FG. The actual attenuation will depend on the molecular weight distribution of the sugars in the wort. Most yeasts can eat pretty much all mono-saccharides (glucose, fructose) and di-saccharides (maltose, sucrose). Some yeasts will also eat tri-saccharides like maltriose. Longer chain sugars and branched sugars (dextrins) are generally not-fermentable. There are conditions in your process that can affect the ratio of fermentable to non-fermentable sugars, and BeerSmith cannot account for all of these, so variation is almost guaranteed.

One thing about BIAB is that many brewers crush their grain very fine, which in turn leads to faster conversion during the mash. With the faster conversion can also come an increase in the ratio of fermentable to non-fermentable sugars, so FG's can be a little lower. If you are worried about it, you can try to compensate by mashing for somewhat shorter times (although this might reduce your conversion efficiency), or modify your recipes slightly to add malts that produce less fermentable sugars (carapils for example.)

You might want to try playing with the highlighted BeerSmith Options (under Advanced):

I suggest seeing if adjusting these parameters would have better predicted your FG's for some of your previous brews.
Brew on

 

[Mothman]

Thanks!