Does overpitching result in a lower FG?

[eadavis80]

I don't think I overpitched, but I don't use a yeast calculator. I harvest my yeast and use a mason jar's worth of yeast (which has about a half inch of yeast on the bottom) added to a 650 ML starter made with 1/2 cup of DME per NB's yeast starter directions. The yeast always ferment in my flask, so I know they're healthy. The last batch I did, an Adventures in Homebrewing vanilla porter, had a target FG of 1.015 and mine was 1.011. Not too far off, and I know expected FG's on recipe kits are ball park figures. That being said, when I racked the beer on top of its vanilla beans, the sample did taste a little dry (thus the low FG). Was this due to too much yeast or did this batch just ferment out better than normal? I used WYeast 1098 and kept temps in the mid 60's throughout its 2-week primary fermentation before racking to secondary when FG was stable.

 

[fantomlord]

you won't finish any lower by overpitching. How low your FG can be is determined by your grain bill, mash temp, etc.

 

[WoodlandBrew]

Pitch rate has some effect on final gravity, but it's not much in my experience. See data here:
http://www.woodlandbrew.com/search?q="side+by+side+starters"

 

[eadavis80]

Woodland Brew - I did not understand any of that science stuff you had in that link - way over my head. I did understand your post, however, which read "Pitch rate has some effect on final gravity, but it's not much in my experience." - I'll go with that and assume as long as I see bubbles in my airlock and an FG somewhere between 1.010 and 1.020 I did okay...

 

[kanzimonson]

Yes, overpitching can definitely increase attenuation. Check out these two articles with some relevant info:

https://drive.google.com/file/d/0B68_EfTWcRxpYVdzVnJjTmlMZUVhTVpSaElwMDBMLXlPV0c4/view?usp=sharing

https://drive.google.com/file/d/0B68_EfTWcRxpWDFvVVhSR2RUendITmtBREpEMGZzT3N0TVUw/view?usp=sharing

 

[dkennedy]

Quick thought- porters sometimes need a bit more time to meld, plus your vanilla addition may add some perceived body (in the same way that dry hopping can trick your tongue into thinking that there is more body in a beer than there really is). I wouldn't worry about slight overpitching, certainly a better practice than underpitching. Sounds like you did everything right, may just need a bit more time to grow up.

 

[WoodlandBrew]

Yes, overpitching can definitely increase attenuation. Check out these two articles with some relevant info:

https://drive.google.com/file/d/0B68_EfTWcRxpYVdzVnJjTmlMZUVhTVpSaElwMDBMLXlPV0c4/view?usp=sharing

https://drive.google.com/file/d/0B68_EfTWcRxpWDFvVVhSR2RUendITmtBREpEMGZzT3N0TVUw/view?usp=sharing

Good articles! I see lots of different effects of pitch rate on beer quality, but I didn't see where it shows that attenuation is significantly impacted.

 

[kanzimonson]

In the pitch rate article, check out Figure 1 showing time vs apparent extract. The units aren't super clear, but it does appear that the higher the pitch rate, the lower the attenuation.

I know it's not proper scientific procedure to estimate units/readings, but it looks like a difference of about one degree plato, which is exactly what the OP is experiencing.

 

[WoodlandBrew]

I agree that it is hard to infer from that graph what the impact of pitch rate is on attenuation. I also agree that it looks like there might be a 1°P difference from the half pitch to 3-fold, but the variation in measurements also looks at least that wide.

 

[BrotherBock]

This may be helpful to you. I don't have the link off hand but its from White LAbs. A general rule I use for estimating cell count:

If you have a jar of yeast, say 400ml. If 40%-60% is yeast solids then you have about 1.2 billion cells per ml. Then it just goes down the line. 20-30% = 600 million/ml; 10-15%=300 million/ml.

I've been using this so I at least have a consistent way to estimate what I have. Even if its not 100% accurate it provides a baselin I can adjust from. I definitely haven't been drastically over or under pitching using this method. If you have a mason jar with measurements on the side this is an easy way to estimate.

EDIT: Maybe it was wyeast....http://www.wyeastlab.com/hb_pitchrates.cfm. Either way I'm confident about the % of slurry as it realtes to cell count. Just having trouble tracking down the source.

 

[eadavis80]

@ kanzimonson - this might be a dumb question, but increasing attenuation just means that a higher percent of the wort will converted to alcohol, right? Thus, it could (in some modest home brewing cases) cause a lower FG than originally intended, yes?