Author Topic: Estimated OG and Priming Sugar  (Read 5991 times)

Offline titus

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Estimated OG and Priming Sugar
« on: February 18, 2012, 07:33:25 AM »
Hi,

After searching the Forum, i didnt find anything relevant to 2 questions i have about Beersmith 2. Maybe someone can help or point me to the right topic.

1. Estimated OG (into fermenter) and mash profiles.

As your guys know, Beersmith has roughly 3 mash profiles: light, medium and full body. Each one has different temperature and times for the enzymatic process. Full body gets you a wort with less fermentable sugars and light body gives you the more fermentable sugars. As i understand, this will impact the estimated OG into fermenter: full body will get you a wort with lower OG than light body (am i wrong?). The equipment i use to make the complete brew is a Braumeister wich is capable of precisely control the times and temperature for the mash. Everytime i selected light body in Beersmith 2 for my recipes, i got almost exactly the OG estimated by the program. On my last batch (a weizen), i selected full body to achieve a beer with more body, like a weizen should be. So, i selected full body on Beersmith and it gave me an estimated OG of 1.052. After boiling my wort the actual measured OG into fermeter was only 1.042 (wich isnt bad), but with a good difference from the value BS estimated (and yes, the evaporation rate is correctly introduced in the software - about 4L/hour).
I then tried to change the mash profile on BS, to see if it affected the etimated OG but it doesnt. I then ask, shouldnt the estimated OG be dependent of the mash profile? Lower OG for full body and higher OG for light body? What i'm letting slip in my theory?  :)

2. Priming sugar and measured final gravity and volume

My second question is related to the priming sugar calculated by BS2. Since i already got a lot of batches with very low carbonation (little viable yeast due to maybe floculation and sedimentation), i now try to bottle my beer after 2 weeks of fermentation. I think this gives me good probability of viable yeasts for bottle fermentation (altough it is strain dependent).
So, in my opinion, the actual priming sugar amount should be calculated taking into account the final gravity at bottling time and volume to bottle (and of course cabonation level). BS2 lets you introduce this 2 values but the sugar calculated is always the same.
Its a bit different to add, lets say, 150 gr of sugar to a wort of 1.020 than to a wort with 1.010 of final gravity (not to mention the volume). Its odd but BS2 gives you always the same amount of sugar no matter what values you put in it. Am i doing something wrong? If you bottle a batch with a somewhat high FG and add the amount calculated by BS2, you can get overcarbonation.
Do you guys know some formula that takes into account the final gravity of the wort to calculate the exact ammount of priming sugar?

Sorry for the long post and thanks for the attention.  :)

T.

PS: im getting blocked to the forum by the anti-spamm script and i really dont know why...

Offline tom_hampton

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Re: Estimated OG and Priming Sugar
« Reply #1 on: February 20, 2012, 08:53:54 PM »
In two parts:

1.  I'm not aware of a dependence between OG and mash-temp.  I've never read anything to suggest such a relationship.  It doesn't fit with my experiences, either.  It sounds more to me like a miss on your efficiency.  1.042 versus 1.052 is pretty big.  I'd look at your grain crush, and try again.  I wouldn't draw any conclusions until you had several repeats.  I monitor my conversion efficiency by measuring the SG of my first runnings.   Then I measure my lautering efficiency by refilling the mash-tun after I've completed my sparge, and measure the SG of this post-sparge extract. 

Link on mash efficiency:  http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency#conversion_and_lauter_efficiency


2.  Bottling conditioning with residual sugars still present is very risky.  It is impossible to predict the remaining sugar, thus you can't calculate the right amount of priming sugar to add.  Beersmith predicts an FG for the recipe, but its little better than a guess.  The actual FG will vary in unpredictable ways based on grain bill, mash temp, boil vigor, yeast strain, fermentation temperature, wort pH, etc.  In short, no there is no general formula for what you want...with the accuracy necessary for controlling the volumes of CO2 in bottling. 

Your beer can suffer from early bottling...for a lot of reasons.  There are a lot of intermediate products created by the yeast during early fermentation.  A longer fermentation on the primary yeast cake, gives the yeast a chance to clean up after itself. 

If your yeast aren't viable at bottling, you would have better results by adding 1/2 a packet of US-05 yeast at bottling with your priming sugar. 
« Last Edit: February 20, 2012, 08:57:20 PM by tom_hampton »
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Offline titus

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Re: Estimated OG and Priming Sugar
« Reply #2 on: February 27, 2012, 03:44:59 AM »
Tom, thanks for your reply.

1. After a couple of readings from a german industry manual, i had a misunderstanding of the mashing process and sugars present in the wort. Anyway, i think i nailed the problem: i started the boil with more water than expected, so the wort into fermenter got more diluted... I have to control this parameter with more accuracy.

2. As of late, i'm always bottling after 2 weeks of fermentation (ales), to get more viable yeast. But in some cases even after only 2 weeks, i get some very low fermentation activity. I think the residual sugar can be measured at bottling time (can be difficult though because bubbles stick to the hidrometer), and that parameter taken into account in the calculation of the priming sugar... But as you said, i cant find literature about it.
As for adding extra yeast, maybe i'll change my fermentation to 3 weeks and then bottling with champagne yeast... Maybe its the more "safe" way to go (carbonation speaking...).

Thoughts? :)

Thanks

Offline tom_hampton

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Re: Estimated OG and Priming Sugar
« Reply #3 on: February 27, 2012, 11:08:28 AM »
Titus-

1.  Aha...that makes sense.

2.  The issue with trying to measure FG is that you don't know where it is going to end.  You could do a forced ferment, at a higher temperature to see what your FG is going to end at.  Then you could calculate the remaining sugar and add additional priming sugar, as you suggest. 

2 weeks is sufficient, but it is on the short side.  I always go a little longer (~3-4 weeks) to ensure any diacetyl and acetyladehyde has been reabsorbed/converted.  Plus, I like a little more clarity than I can get in two weeks. 

It puzzles me that you aren't getting good bottle fermentation after only two weeks.  Without physically filtering there should be LOTS of viable yeast left...even in a very clear beer.  I have no issues even after 6 weeks, even if I rack into a secondary..with a beer that I can literally see through. 

So, to me it seems like something about your fermentation process is either causing the yeast to die off/drop out prematurely...or something in your bottling is preventing them from fermenting/carbonating.  I'd think about your initial yeast health and pitch rate (starter?), fermentation temperatures, do you crash-cool, bottle storage temps and duration, how much priming sugar do you add, etc. 

You might also conduct an experiement with some of your finished beer.  Prime the batch as normal, then take a bottle and put an airlock on it.  Then watch for signs of fermentation.  If you wanted to get really scientific you could capture the CO2, and measure the volume produced. 

If you decide to add bottling yeast, I'd stay with a brewer's yeast.  Champagne yeast may attenuate more than a standard ale yeast.  So, you could end up with overcarbonation or bottle-bombs.  If you really want to try Champagne yeast, I'd start low on the sugar and try a few test batches.  Most people I know use an American Ale yeast (neutral, clean flavored) for bottling. 

R.I.P.:Belgian Blonde
On Tap: Apfelwein, Kolsch(v2), Pumpkin Ale, Belgian Specialty 
Aging/Storing: Coffee Porter, Chocolate Porter, Flanders Red, English Barlywine
Fermenting: Maggie's Altbier
Next Up: PtE(1.1), Belgian Dubbel?

Working thru all BCS recipes

Offline titus

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Re: Estimated OG and Priming Sugar
« Reply #4 on: February 28, 2012, 04:42:14 AM »
Tom, thanks for all your insight.

Last time i got very poor carbonation was with a Scotch type beer. It had a very vigorous fermentation and in the second week it drop considerably. I think it had to do with the strain hability to floculate and sediment (cant remember what strain was, only that it was from Wyeast Labs with a standard starter).
I know a longer fermentation period is better and i think i'll change that as you suggested. I'll try to go with 1 week primary, 2 weeks secundary and will add less than half the value recommended of dry yeast at bottling, just in case. I've got Bioferm Champ so now i'll have to use it... The site says it produces very few by-products and has good tolerance.
I'm starting to prepare another batch (dry stout), and i'll use this method. Let's see if i get good results. :)
Thanks again.

Offline Myk

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Re: Estimated OG and Priming Sugar
« Reply #5 on: February 28, 2012, 12:24:24 PM »
BS2 calculates carbonation based on the estimated bottling volume rather than measured volume. That's all I can figure out about it keeping the same calculations.
FG has nothing to do with carbonation unless you happen to be over the alcohol tolerance for the yeast or you're trying to hit on bottling with residual sugar (which as Tom pointed out is not very accurate).

Scottish Ales are very low carbonation. If you carbonated according to the style sheets low carbonation is what you should've got. Strong Scotch Ale shouldn't be over the alcohol tolerance for any beer yeast I've seen (but I don't know what yeast you have available there).

For carbonation amounts I've tried according to BeerSmith's figures 1.9 volume is pretty flat. 2.2 volumes is perceptible in head at pouring but not much more. 2.7 volumes is pretty burpy.