Attenuation calculator

[Edan Z]

I noticed that all my beers based on a similar recipe, pitched with a 1L starter of WLP530, starting at 1.063 OG, always finish up at 1.008 FG. According to the BF recipe calculator that corresponds to a "custom" attenuation of 84% for that yeast. I have gotten in the habit of using that custom attenuation figure in this recipe, since I know what my FG will be based on previous results with the same recipe/mash schedule, etc.

I just noticed, however, that when I plug my figures into the BF stand-alone ABV calculator, the "apparent attenuation" given is slightly higher at 87%. All other figures match, except the % attenuation.

I was wondering why there is a discrepancy between the recipe calculator and the ABV calculator in the attenuation figure. Does the recipe calculator figure refer something other than apparent attenuation?

Incidentally, for my last brew, I actually forgot to make a starter before brew day. I started mashing before I realized I forgot the starter. It was a fresh (less than 30 days old) Wyeast 3787 activator pack. So I decided to bite the bullet and pitch it anyway. Fermentation took off fine in less than 12 hours as usual. Five days later the FG was at 1.010, and 10 days later is still 1.010. I was wondering if the attenuation is lower because I didn't make a starter, or because I added some crystal malt to the recipe, or maybe both?

 

[DL]

I just spotted the same issue with the different attenuation results between the recipe builder and ABV Calculator. Did you ever get to the bottom of it?

 

[Bigbre04]

I noticed that all my beers based on a similar recipe, pitched with a 1L starter of WLP530, starting at 1.063 OG, always finish up at 1.008 FG. According to the BF recipe calculator that corresponds to a "custom" attenuation of 84% for that yeast. I have gotten in the habit of using that custom attenuation figure in this recipe, since I know what my FG will be based on previous results with the same recipe/mash schedule, etc.

I just noticed, however, that when I plug my figures into the BF stand-alone ABV calculator, the "apparent attenuation" given is slightly higher at 87%. All other figures match, except the % attenuation.

I was wondering why there is a discrepancy between the recipe calculator and the ABV calculator in the attenuation figure. Does the recipe calculator figure refer something other than apparent attenuation?

Incidentally, for my last brew, I actually forgot to make a starter before brew day. I started mashing before I realized I forgot the starter. It was a fresh (less than 30 days old) Wyeast 3787 activator pack. So I decided to bite the bullet and pitch it anyway. Fermentation took off fine in less than 12 hours as usual. Five days later the FG was at 1.010, and 10 days later is still 1.010. I was wondering if the attenuation is lower because I didn't make a starter, or because I added some crystal malt to the recipe, or maybe both?

crystal and mash temp can def have an effect on the FG.

The real advantage to a starter(to my knowledge) is that you get a significantly higher cell count in your initial pitch. Add to that that you have "active" fermentation. Your ferment should go(start) very quickly as those active yeast will have better access to O2 and will grow even faster.

For dry yeast they dont recommend a starter anymore, if you have a properly sized pitch, you shouldnt need it(and it is a solid vector for infection if you are not very careful). I dont know about liquid yeast these days. In the old days we used to buy way undersized yeast pitches to save a few thousand bucks and prop it up in a single batch instead of a double.

dunno about the dif in the calculator though. that being said, i just checked the grav on a kolsch that according to Apex shouldnt get higher then 78% atten and it is at 83% according to the stand alone calculator this morning.

Looked back at my previous kolsch brew and it was at 82%...so maybe that is just Apex being conservative.

I will look at chico and voss and see what they expect on the bag vs what i am getting in the tanks.