Author Topic: Lactose settings in Beersmith  (Read 1500 times)

Offline andyn2001

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Lactose settings in Beersmith
« on: February 19, 2019, 10:34:06 AM »
I have brewed 2 Milk stouts recently for the first time. Both FGs are 3pts too high. In the Beersmith settings for Lactose I have checked the Not Fermentable box, but still I am out with my FGs.

Now, I have just been playing with the settings for Lactose, if I change the Yield from 76.10% to 100% my Estimated FG goes up 2 pts, leaving me a lot more happy with a 1pt diff.

So, my question is, should the Yield be 100% for Lactose?? I've also got to ask, why does the Yield affect the FG when "Not Fermentable" is checked?? Surely Not Fermentable means no yield and the yield should be ignored, changing it should not make any difference, but it does.

If not, then have others experienced higher than estimated FGs with Milk Stouts?  Is the Lactose making the yeast struggle and give up early?  I have pitched plenty of yeast. 1 pkt Fermentis S-04 for an estimated 5.5% beers, that both ended at 5.1%.
« Last Edit: February 19, 2019, 11:00:50 AM by andyn2001 »

Offline dtapke

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Re: Lactose settings in Beersmith
« Reply #1 on: February 19, 2019, 04:57:31 PM »
I've recently brewed a few milk stouts, and can't say as i've had any issues, Could you perhaps load up a .BSMX recipe and perhaps I could take a gander as to why you're having this issue?

I should add, I'm not one to fuss over .002 gravity points usually. So even if a beer turned out a few gravity points one way or another I wouldn't concern myself with it, however my last two milk stouts have been spot on (actually started .001 high and finished .001 high, so whatever!)

The biggest factor in attenuation is generally mash temps, are all of your other beers with similar mash schedules hitting the numbers perfectly?
« Last Edit: February 19, 2019, 05:01:42 PM by dtapke »
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Offline andyn2001

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Re: Lactose settings in Beersmith
« Reply #2 on: February 20, 2019, 01:58:02 AM »
Yes, get no prob hitting other FGs, normally always spot on or 1pt out.

Can you explain why the Yield figure in the Lactose settings is set to 76.1%, and the FG estimate changes if I change it to 100% and "Not Fermentable" box is checked?? Surely if Not Fermentable is checked 100% of the sugar is added to the FG, whereas Beersmith seems to be adding 76.1% of the sugar. This is why in my opinion the estimated FG is only estimating 1.016 yet I am getting 1.019/1.020.

For your recipe how much Lactose did you add? I added 5.8%, if you added less tht may explain why your FG is closer???

Offline Oginme

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Re: Lactose settings in Beersmith
« Reply #3 on: February 20, 2019, 05:43:44 AM »
I think your understanding of yield is not correct.  This refers to the yield in gravity contribution s compared to pure sugar.  When you increase the yield to 100%, you tell the program that the gravity you realize from pound of lactose will give you a gravity of 1.046 in a gallon of water.  When the yield is set at 76.1%, the gravity for the same pound would be 1.035.  Thus when you change the yield, you change the estimate of the OG for the recipe higher by a couple of points for the 100% yield.  When you then check the non-fermentable box, this gives you an increased FG estimate. 

So the question is, are you hitting your OG targets with the lactose set at 76.1% yield or 100% yield?  That determines the actual contribution of the lactose you are using.  When it comes to the final gravity, so much depends upon the fermentability of your wort, the actual potential of your grain bill, the make-up of your grist in terms of non-fermentable sugars (other than the lactose), the health and quantity of your yeast pitch, the temperatures at which the wort is fermenting, etc.   There are just so many factors which play into the estimation for FG, that I take the same tone of dtapke in not worrying about it too much if I am even as much as a few points off.  As long as the gravity reading is consistent over at least three days, that batch of wort has hit the maximum attentuation that it can reach with the given parameters. 

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Offline andyn2001

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Re: Lactose settings in Beersmith
« Reply #4 on: February 20, 2019, 06:15:43 AM »
I'm hitting OG perfect. I use Beersmith for all sorts, it's just these two Milk Stouts where I am out. I'm pitching enough viable dry yeast. 1 packet S-04 for 16 litres of a 5.5.% beer.

Ok, I have another theory.....the first one I bottled after 2 weeks and the FG had been flat at 1.019 for a week. I only put in 1.8 vols sugar, yet this beer carbed up like I had put 10 vols of sugar in!!  I took a gravity reading of one of the bottles, and it had gone done to 1.016, the expected FG, but after another 6 weeks.

Do Milk Stouts take more than 2 weeks to ferment to hit the FG. S-04 is fast fermenting yeast, just wondering is it because of the lactose this pattern changes and it takes a lot longer to get those last 2 or 3 points of gravity to ferment?

I know you say don't get hung up on this, but I am trying to go commercial so really need to understand why I am missing the FG just on this particular beer style. If I'm aiming for 5.5%, I need to get 5.4-5.6% to be be happy, not 5.1% :)

Offline Oginme

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Re: Lactose settings in Beersmith
« Reply #5 on: February 20, 2019, 06:27:58 AM »
The best way to test for ultimate fermentability is to do a forced fermentation test.  When you brew, take a pint  quart or so of wort into a container and pitch an abundance of yeast.  Let that sit at relatively warm temperatures for a number of days and let the yeast do its thing.  Then check the gravity of the resultant beer.   The excess of yeast and the warm temperatures will give you an ultimate end point of FG for that wort.  Actual fermentation may not quite reach that same end point, but should be pretty close.

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Offline dtapke

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Re: Lactose settings in Beersmith
« Reply #6 on: February 20, 2019, 07:13:25 AM »
sounds like either lack of o2 or lack of yeast if it pepped up after bottling.
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Offline andyn2001

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Re: Lactose settings in Beersmith
« Reply #7 on: February 20, 2019, 07:56:47 AM »
I'll try a packet and a half next time, even though 1 packet should be enough. Maybe the yeast trying to break down lactose stresses the yeast and it gives up a bit??

« Last Edit: February 20, 2019, 01:33:02 PM by andyn2001 »

Offline dtapke

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Re: Lactose settings in Beersmith
« Reply #8 on: February 20, 2019, 12:13:17 PM »
fwiw scaled my last recipe down to what i can only assume to be your levels,(5Gal?) and added us05 as a yeast instead of what i use and it asks for 290B yeast cells, or 17.9 grams of dry yeast. which would be almost 4 of the 5oz packs of yeast that are usually sold at stores, and thats with a "fresh" pitch.

personally, although i know many places use us05, i personally only use liquid, and perform cell counts on my pitch to be certain that i'm pitching an appropriate amount of yeast.

It seems relatively clear to me that the issue is more likely in your process than in the software. There's two ways of addressing this, adjust your practice to pitch appropriate yeast to appropriately oxygenated wort and be certain that your mash temps are appropriate; Or if you're consistently off by the same amount across several batches, just take that differential into account when formulating your recipe.

I've got a friend who is constantly and consistently "off target" by .005 but he refuses to change anything because he finds it much simpler to just adjust for that, always setting up his recipes for .005 higher than what he wants it to be.

Again, feel free to drop a BSMX file here with a recipe and accurate session data and perhaps we can find the issue, but without any of that information its a guessing game!
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Offline andyn2001

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Re: Lactose settings in Beersmith
« Reply #9 on: February 20, 2019, 02:36:51 PM »
Beersmith calculated I needed 9g of yeast 160bn cells. I added a full packet (11g) of S-04, so should have been a little spare.

Attached is the Beersmith file, hopefully something obvious is going on!

Offline Oginme

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Re: Lactose settings in Beersmith
« Reply #10 on: February 20, 2019, 04:37:58 PM »
Looking at the recipe, you came in a point high in gravity at the end of boil, which contributed some to the higher FG.  I am guessing that the difference between the gravity from the mash and the gravity at the beginning of the boil is the lactose(?).  Your apparent attenuation is low for S-04, which does lead to the possibility that you did not reach a stable gravity before bottling.  Your pitch rate seems fine.  What was the temperatures that the beer fermented at?
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Offline andyn2001

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Re: Lactose settings in Beersmith
« Reply #11 on: February 21, 2019, 02:15:47 AM »
Sorry, not bottled this one yet, it's the one I brewed last week, but appears to have stopped at 1.019.

Fermented at 18-19C, raised to 20C last few days.

I'll leave another week, but this has followed same pattern as first one. As it stand ABV is 5.1% v 5.5% estimate, and I was one pt up on my OG.

So, no obvious reason so far why this only happens with my milk stouts?! Porters and normal stouts are fine, they attentuate correctly and hit the correct FG.

I'm edging to adding in more yeast next time. I suspect there is something with the lactose stressing the yeast.Its the only thing I can think of.

Offline dtapke

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Re: Lactose settings in Beersmith
« Reply #12 on: February 21, 2019, 07:32:32 AM »
do you aerate or oxygenate post boil?

the fact that the bottling provided a lower gravity shows the issue seems to be there, I'm not familiar enough with pitching dry yeast to be of much help.

it does seem odd to me to be concerned over a mild difference in attenuation when you've got such a large discrepancy from your pre-boil to batch volume. If you boiled off at the rate according to your profile, performed a 60 minute boil, your OG should've been closer to 1.060+

your preboil was .005 high, yet somehow your batch volume was only .001 high, I think perhaps another potential issue is in accurate measuring of the batch?
32g eHERMS
Drinking: Dopplebock, NEIPA, Pils
Primary: empty
Secondary/Lagering:
Next Brew: RIS