Beersmith Fermentable / Non-fermentable

[Mothman]

Sorry ... another question from this noob. lol

I have my current batch in primary, about 12 days in.

I'm doing the extract version of Biermunchers Blue Balls Belgian shown in Post #5 here: https://www.homebrewtalk.com/showpost.php?p=261929&postcount=5

Well, mostly anyways... I threw in a bit of left over dextrose I had, and added a bit of flaked oat to the wheat steep, and changed the yeast to US-05.

It appears that fermentation has stopped, and has seemed that way for several days (krausen fell long after about 5 or 6 days, airlock activity has been mostly non-existent for days), so I just took my first FG reading.

When I set up the recipe in Beersmith, I marked the flaked wheat and oats as Non-fermentable, as they were steeped alone, no base malt, so no conversion... right? The steep would add to the OG, but shouldn't ferment out, so should leave the FG higher... I think?

With them set to non-fermentable, the estimated FG was 1.015.

However, my FG reading today was 1.011.

I just tried switching the wheat and oats in Beersmith to fermentable, and that changed the estimated FG to 1.010, much closer to where I am at now.

The estimated OG in Beersmith was 1.054, I measured 1.050, but that estimate is at a default 70% brewhouse efficiency in the equipment profile... and I'm not sure how accurate that is or how that would impact the OG for this recipe which is extract + steeping a bunch of wheat and oats... and I did forget to sparge the grain bag,, and instead topped up to pre-boil with plain water... dumb, I know... so if I'm understanding right, it's no surprise the OG was a tad low...

I wondered if my hydrometer is maybe off 4 or 5 points, but testing in water (tap water, so not ideal I guess), it reads 1.001, so it seems reasonably accurate.

Anyways, I'm rambling now... just looking for a bit of insight into what may have happened here.

On a side note, I drank the hydro sample and it's awesome!!

 

[Mothman]

Sample. Not sure why it's rotated lol.

 

[Oginme]

There are so many factors that play into the actual achieved versus the prediction of FG, that I don't worry too much if I miss it by a few points (especially on the low side). Modeling programs usually use an average attenuation for each yeast and fermenting higher in the temperature range can drive the yeast to eat through more of the sugars (higher attenuation).

Since you did not have any enzymatic grains in your grain bill, the chances that the starches from the oats and wheat converted are very low. Still there may be some breakdown of the starches during the steaming and rolling of the oats and corn which may account for the difference.

Given that you threw in some dextrose and that you were low on your OG to start with, you are probably not too far off from what the program may have predicted.

As the sample tasted good, I wouldn't worry too much about it. I would however recommend that you drink this one down fast, as there are bacteria which will feast upon the starches if left too long in the bottle (or keg).

 

[Mothman]

Thanks Oginme.

In terms of the dextrose, I included that in the Beersmith recipe, so I'd think BS has taken that into account.

It also could be due to how I'm using Beersmith... the predicted values change whether I set the recipe as a partial mash or as extract.

On my first brew (extract + specialty steep), I found setting it the partial mash resulted in close to measured values, while setting it to extract had the measurements off.

This time around, if I set it to extract, the FG is close to what I got, but the OG is lower than what I got.

So, I don't know.

In the end, I am not worrying about it, just trying to work out, as I move forward, some of these little questions.

I hadn't heard about the bacteria / starch thing before.... so is that a factor in any homebrew that includes wheat/oats? And how long is "too long"? Are we talking months?

 

[Oginme]

When you set the recipe type to 'partial mash' the program uses the extract and added sugars as it would for an extract recipe. It then calculates a mash efficiency to draw out the remaining sugars from the mini-mash to account for the remainder. It will adjust this mash efficiency as needed to satisfy the sugar balance to reach the balance set by the brew house efficiency in your equipment profile.

For an 'extract' recipe, it assumes the sugars are fixed, drawing from the direct addition of extract and sugars plus the steeping efficiency set for the specialty grains to define the amount of sugars available. Any changes from this are usually related to volumes and volume losses throughout the system.

If the partial mash setting gets you closer to your actual values, then you may need to check your measurements on volume to get the water in balance.