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Rogue_Atom87

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Trying to understand how yeast works and modify recipes/yeast to get the FG I am looking for. For instance when I plug a recipe into Brewfather and the OG is high 1.06's and I select a 70% attenuation yeast as it is the preferred for recipe I may only get a final gravity of low 1.02's. What modifications do you need to do to get it down closer to 1.015 or a higher ABV. In Brewfather if I increase mash time or double amount of yeast there is no change in the predicted FG.

Also is a FG around 1.02 necessarily bad? What are the flavor differences between 1.02 and 1.015?

Is there a way to get a yeast to have better attenuation? Yeast starter, pitch more, etc..

Example - Just playing around with the below in Brewfather based on some research for an orange creamsicle recipe

1.5 gallon BIAB. 60 min at 152F. BH efficiency 63%
Grain Bill
2.5lb Pale ale 2-row
.4lb Flaked barley
.25lb Carapils
.25lb Lactose.
US-05 at 81%

OG - 1.053
FG - 1.015
The OG and ABV fall into the green on recipe but the FG shows 1.006-1.012. What do I need to do to raise the ABV to say 5.5% or 1.011?
 

dmtaylor

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Adding extra yeast won't help at all. This isn't really a yeast thing.

It looks like you should simply increase the pale ale malt from 2.5 lb to about 2.75 or 3 lb, that will give you more alcohol. A final gravity of up to 1.020 is probably normal for a creamsicle style beer. If that's what you want then just increase the base malt and don't change anything else. But if you want it more dry and not so sweet, then...

Mashing for 90-120 minutes or even longer like overnight would improve attenuation and reduce FG significantly. Also definitely ditch the lactose which will not ferment, as it would be doing the opposite of your goal, IF you don't want a creamsicle.

Make sense?
 

McKnuckle

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Attenuation is based on - in chronological order - grain bill, mash temps, yeast selection, yeast pitch rate, oxygenation, and fermentation temperature. For a given style, some of those variables can be modified and others really can't. But those are the main tools at your disposal.

In your example, lactose, which is not fermentable, adds gravity points to the FG that can't be depleted no matter what you do. US-05 is already an above average attenuative yeast at 80%+. You can ferment it up to 70-72F without much risk and that may help it finish completely. You can mash low and long to ensure a fermentable wort.

You could select a highly attenuative yeast if you're really trying to dry out a high OG wort.

Finally, don't put too much trust in software to interpret every variable accurately, especially mash temperature.
 

Mtrhdltd

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Mash at a lower temp. That will make more fermentable sugars. Higher alcohol with less body. I just kegged a batch that finished at 1.003 instead of 1.010 because I let the mash temp drop too low. Attenuation was in the 90s.
 

Sammy86

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Remember, yeast are a living organism they are going to do ehat they please sometimes regardless of how we prepare wort and them.

However, as stated above there things you can control...

grain bill, mash temps, yeast selection, yeast pitch rate, oxygenation, and fermentation temperature.
Grain Bill and Mash temp will definitely contribute to the FG. If you want a dryer beer mash lower-think Pils, Helles, Lagers in general...mash higher for more residual sweetness think-Pale Ales, IPAS, Stouts.

The difference between 1.020 and 1.015 isn't very much in my opinion youre going to have a sweeter beer.

You really want to drive down FG when you want the beer to be more dry and crisp.

Hope this helps!
 
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Rogue_Atom87

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Thanks. The above answers definitely help.

In Brewfather when I adjust the mash length or temperature there is no affect on ABV. Also when adding grain to increase OG the ABV goes up.

For instance in the creamsicle recipe I mentioned above adding .5lb of 2-row took ABV to 1.018 from 1.015.

I know hard for app to calculate but in real world what changes should you see if you mash for 30 min longer, drop temp from say 152 to 149, or do both?
 

dmtaylor

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I know hard for app to calculate but in real world what changes should you see if you mash for 30 min longer, drop temp from say 152 to 149, or do both?
Neither the mash time nor temperature change attenuation by very much unless the difference from normal is pretty significant. A 30 minute longer mash will reduce FG by about 0.001-0.002, whereas a small temperature difference of 3 F probably will only reduce FG by about 0.000 (zero) to 0.001, probably couldn't even tell a difference from a small temperature change like that. But if you reduce temperature by much more say at least 5 or 6 F or more, then you can get an extra point or two out of that. So your best bet might be to do both, extend your mash time for 30-60 minutes or even longer (overnight is actually an easy option if you ever wanted the beer to come out super dry), AND reduce mash temp quite low, 147-148 F is good, although I really wouldn't recommend going any lower than that because starches don't gelatinize very well below that point, i.e., you might just end up hurting efficiency and get a starchy mess if you tried mashing at say 144 F or something super low like that.
 
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Rogue_Atom87

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Thanks Taylor. I am going to drop to 149F and extend to 2 hours. Pretty easy for me to do as I modified my sous vide to fit in pot so I can maintain temps well.
 
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