BeerSmith Est. OG not correct?

[Lost_Arkitekt]

Well, let me first say that the Est. OG per a given efficiency isn't calculated correctly...or I'm wrong in assuming OG isn't linear.

For my last batch, my Estimated Pre-Boil Gravity was supposed to be 1.040 at 13.06 gallons. Then, my Estimated O.G. on BeerSmith's sliding scale for my recipe was 1.050 for post boil. (O.G. for post boil and into the fermenter should be the same because I'm not boiling off water.) If you actually do the math, that isn't possible.

40 GP * 13.06 = 522.40
522.40/11.18 = 46.72

Even rounding up that would give me 47 GP. So, my gravity SHOULD be 1.047. I have no idea why BeerSmith says 1.050.

Can someone help?

 

[LLBeanJ]

Can you post the recipe?

 

[Lost_Arkitekt]

Here is the "recipe." I figured that BeerSmith adjusts OG for shrinkage and trub loss. Since the trub is actually sucking up water with sugar in it, then, the calculations shouldn't matter. So, I did the math for the "Batch Volume" and it came out right. However, I took a refractometer reading after the wort came through the chiller, so that should be the actual O.G. It measured 1.046. My pre-boil for gravity measured spot on what B.S. suggested -- 1.040. For BeerSmith, I don't think you should include trub loss because that is taking some of the sugars with it...not just water. That's like pouring 1.050 SG from a kettle to a gallon jug. You only have one gallon in the jug, but it should still be 1.050. Right? If it was straight evaporation, then I'd agree, but there is some absorption of sugars with the trub.

Am I wrong on thinking that trub shouldn't matter?


Desert Fox Hefeweizen

Weizen/Weissbier (15 A)

Type: All Grain
Batch Size: 10.50 gal
Boil Size: 13.06 gal
Boil Time: 90 min
End of Boil Vol: 11.18 gal
Final Bottling Vol: 10.00 gal
Fermentation: My Aging Profile


Date: 02 AUG 2014
Equipment: BIAB Keggle (15.5 gal)
Efficiency: 70.00 %
Est Mash Efficiency: 71.7 %
Taste Rating: 35.0


Taste Notes:



Ingredients
Amt Name Type # %/IBU

11.60 ml Lactic Acid (Mash 60.0 mins) Water Agent 1 -
0.50 Items Campden Tablet (Mash 70.0 mins) Water Agent 2 -
9 lbs Pilsen (Dingemans) (1.6 SRM) Grain 3 45.0 %
9 lbs Wheat, White (Cargill) (2.9 SRM) Grain 4 45.0 %
1 lbs 8.0 oz Carafoam (Weyermann) (2.0 SRM) Grain 5 7.5 %
0.50 oz Hallertau (HopsDirect) [4.70 %] - Boil 60.0 min Hop 6 4.5 IBUs
1.00 oz Hallertau (HopsDirect) [4.70 %] - Boil 30.0 min Hop 7 7.0 IBUs
3.00 tsp Irish Moss (Boil 10.0 mins) Fining 8 -
1.00 tsp Yeast Nutrient Wyeast (Boil 5.0 mins) Other 9 -
1.0 pkg Bavarian Wheat (Wyeast Labs #3638) [124.21 ml] Yeast 10 -
8.0 oz Carawheat (Weyermann) (50.0 SRM) Grain 11 2.5 %


Gravity, Alcohol Content and Color

Est Original Gravity: 1.050 SG
Est Final Gravity: 1.016 SG
Estimated Alcohol by Vol: 4.4 %
Bitterness: 11.5 IBUs
Est Color: 5.3 SRM

Measured Original Gravity: 1.046 SG



Mash Profile

Mash Name: Decoction Mash, Double
Sparge Water: 0.89 gal
Sparge Temperature: 168.0 F
Adjust Temp for Equipment: FALSE


Total Grain Weight: 20 lbs
Grain Temperature: 72.0 F
Tun Temperature: 72.0 F
Mash PH: 5.30

Mash Steps

Name Description Step Temperature Step Time

Acid Rest Add 48.01 qt of water at 112.8 F 110.0 F 15 min
Protein Decoct 11.14 qt of mash and boil it 131.0 F 10 min
Saccharification Decoct 18.03 qt of mash and boil it 158.0 F 15 min
Mash Out Heat to 168.0 F over 10 min 168.0 F 10 min

Sparge: Fly sparge with 0.89 gal water at 168.0 F
Mash Notes: Used for some authentic German styles. Attempt to draw decoction from the thickest portion of the mash. Profiles vary. Some traditional German mashes use a long acid rest at 40 deg C. Also some sources recommend the decoction amount be given a 15 minute saccharification rest at 158 F (70 C) before boiling it.

 

[ajdelange]

The relationship between dissolved extract and specific gravity 'points' is indeed not linear (though the non linearity is very small). To accurately compute gravity changes through dilutions one must convert points to °P, calculate the extract from that, add (or subtract in the case of concentration through boiing) the water change, recompute Plato and convert that back to SG.

 

[LLBeanJ]

You are correct that trub shouldn't matter and it doesn't. When BS gives an end of boil volume, that is at boiling temp and includes the compensated volume for shrinkage (insert Seinfeld reference here). As the wort is cooled it shrinks down to your batch volume and that is where the post-boil OG should be measured, and you have already confirmed that if the gravity points from pre-boil are divided by batch volume (10.5 gal), you end up with 50 points.

As far as why your cooled, post-boil wort came out 4 points low, I'd have to chalk it up to less than planned efficiency or incorrect volumes (either pre- or post-boil) or a combination of both, or possibly a measurement error. I know people love their refractometers and I even have one myself, but I've found that with mine I get readings all over the place from the same sample. Maybe mine's a POS (it probably is) and yours is relatively accurate, but I'd like to know what a hydrometer would tell you for OG.

 

[Lost_Arkitekt]

Okay...regardless of the non-linearity, the software should take that into consideration, correct? My refractometer measures in OG not degrees-Plato. The software also supplies specific gravity, which being software, I'm assuming it does all these calculations in the background.

I still think that trub loss should be considered like a sponge...it is soaking up wort with sugars...not just water, so the concentration of sugars per/volume before trub loss should be the same after. I have no scientific testing to verify this, but it makes sense. Evaporation is leaving sugar...removing water. Trub (hops, etc.) is soaking up wort that has the same concentration of sugar in it as the rest of the wort. Therefore, amount of sugars in trub (concentration) should be the same as fermenter. Your gravity shouldn't go UP. It should be the same as before trub loss--after accounting for shrinkage.

@LLBeanJ ... that 10.5 batch volume accounts for trub loss. If I take the trub loss out, then the volume goes up...and the S.G. goes down. For instance. I don't lose very much to trub...and get almost all of my liquid out...lifting up transfer tubs and chugger pump. I have my trub loss at .25 gallon.

So, if I use the number 10.75 (no accounting for trub loss but accounting for shrinkage), the Est. O.G. should be as follows:
40 * 13.06 = 522.40
522.40/10.75 = 48.595 so 1.049

I'm saying that BeerSmith should take trub loss out of the O.G. equation. It takes sugar with it at the same concentration as what is going into the fermenter--regardless of what my actual measurements are.

 

[Lost_Arkitekt]

Seeing that I capped the cooled wort off last night and have to pitch this morning, I'll take an actual gravity reading. I calibrated my refractometer and took two reading...getting the same specific gravity.

 

[LLBeanJ]

@LLBeanJ ... that 10.5 batch volume accounts for trub loss. If I take the trub loss out, then the volume goes up...and the S.G. goes down. For instance. I don't lose very much to trub...and get almost all of my liquid out...lifting up transfer tubs and chugger pump. I have my trub loss at .25 gallon.

So, if I use the number 10.75 (no accounting for trub loss but accounting for shrinkage), the Est. O.G. should be as follows:
40 * 13.06 = 522.40
522.40/10.75 = 48.595 so 1.049

I'm saying that BeerSmith should take trub loss out of the O.G. equation. It takes sugar with it at the same concentration as what is going into the fermenter--regardless of what my actual measurements are.

Makes sense what you're saying about trub loss from the BK and I agree with you that it should not come into play wrt gravity points. Not sure why BS would behave this way. I don't have any trub loss from the BK, so I have never come across this issue. It might be a good question to ask Brad at BS.

Edit/Update: I was just playing around in BS and I'm getting the same behavior. Post-boil trub loss is definitely affecting FG and this shouldn't be the case. As a workaround, I'd suggest that you change the trub loss field to zero and increase your batch size to 10.75, then increase your fermenter loss to .75. This will ensure that you have enough fermentables to yield your intended FG post-boil and into the fermenter. And since you will be leaving .25 gal behind in the kettle, you would then need to remember that you will only have 10.5 gal going into the fermenter even though BS is telling you there should be 10.75. It's a bit half-arsed, but it would work.

 

[Lost_Arkitekt]

So...LLBeanJ was onto something. My calibrated refractometer isn't all that "awesome". I'm going to just use it as a guide from now on. My OG into the fermenter was 1.051...higher than anticipated.

Regardless, though, trub loss shouldn't be in the BeerSmith calculations for specific gravity. The estimated gravity should be 1.049 not 1.051.

That means everyone should give themselves a little pat on the back for achieving better efficiency. Hahaha.

 

[LLBeanJ]

Regardless, though, trub loss shouldn't be in the BeerSmith calculations for specific gravity. The estimated gravity should be 1.049 not 1.051.

Agreed. See update to my last post.

I think I'll send an email to Brad at BS and see if he has any input as to why BS is doing this.

 

[ajdelange]

Yes, your software should take the non linearity into account but that doesn't mean it does. To convert SG to Plato is easy (just plug into the ASBC polynomial) but to get SG from Plato, which you need to do after allowing for the water addition or loss isn't so easy as the polynomial needs to be inverted and it is third order. This is quite doable in a calculator or computer of course but not everyone that writes calculators and spreadsheets understands all this. If they did we'd be working in °P as professional brewers do.

As for trub: it counts if it floats or sinks to the bottom. In either case it is material removed from solution. If it stays in suspension it doesn't count because it is the same density as the wort.Once you strain or centrifuge it out, suspended or not, it does count as it is mass that has been removed from the liquid and must, therefore, be deducted from the total extract.

 

[LLBeanJ]

After spending some more time messing around in BS trying to figure this out, it does seem to be working correctly for me. When I throw a recipe together using your malts, efficiency, batch size, and trub loss, I get pre- and post-boil numbers that are correct. BeerSmith's numbers appear to be doing everything right to ensure that post-boil OG is at the recipe's intended OG. I'm wondering if there is something in your BS setup or recipe that is not quite right. That is, something that would suggest your post-boil OG should actually be 1.049 (including the kettle trub) even though the recipe OG is 1.050. Granted, it's only off by 1 gravity point, but still, it shouldn't be off once the OGs are rounded up/down to the next point.

One thing I noticed is that the Carawheat is listed at the bottom of your recipe after the yeast. Is the "Add after boil" box inadvertenly checked? It's just a hunch, but it would explain why BS is calculating 1.049 post-boil even though there are 1.050 in total sugars.

 

[Lost_Arkitekt]

So, I was doing the Gordon Strong method of steeping CaraWheat (actually I put in grain bag and added into final 10 minutes of boil). However, once I changed the designation on BeerSmith, it bumped my estimated pre-boil gravity to 1.041 which gives me the 1.050 I need with the math.

Wow...crazy. Now, I'm pissed that my refractometer reads perfect for pre-boil gravity...or close enough, but post boil was about 5 points off...46-ish versus 51 with hydrometer. Now it seems as though the refractometer was a waste of money. Ugggh.

Thanks for all the help everyone.

 

[brewfun]

Two Tips:

1) BeerSmith has different has a different rate for steeped grain. It defaults at 15%. This is changeable in the Options > Advanced menu.

2) In using "Brewhouse Efficiency" as its main calculation, BeerSmith doesn't lower the anticipated OG when loss to trub is increased. It compensates by increasing mash efficiency and eventually it will exceed 100%. It isn't always noticeable with low loss numbers.

The liquid locked up in trub will be the same gravity as the rest of the batch. However, as AJ pointed out, the loss of protein and other solids during the boil and chill will decrease the gravity. I see a 0.2 Plato gravity loss pre to post chiller due to cold break.