OG-FG Question

[TheHunk]

I am on my 4th brew and I had a question about OG and FG. My 2nd and 3rd brews never got close to the FG suggested in the literature. My second brew (Am. Wheat from True Brew) ended @ 1.020 @ 68 degrees, after 2 weeks. The OG for that brew was 1.052. My third brew (Ironmaster American Light w/ 2 lbs of extra light DME) had a FG of 1.018 @ 68 degrees after a week. This brew's OG was 1.050 @ 70 degrees. I used the yeast that came with the kits. Should I have added another yeast pack?

TIA,
Wes Hunkler

 

[phatuna]

Sound like it was dry yeast? If so, I would think that should have been enough. If it was liquid yeast, you should be making a starter.

 

[Yooper]

I am on my 4th brew and I had a question about OG and FG. My 2nd and 3rd brews never got close to the FG suggested in the literature. My second brew (Am. Wheat from True Brew) ended @ 1.020 @ 68 degrees, after 2 weeks. The OG for that brew was 1.052. My third brew (Ironmaster American Light w/ 2 lbs of extra light DME) had a FG of 1.018 @ 68 degrees after a week. This brew's OG was 1.050 @ 70 degrees. I used the yeast that came with the kits. Should I have added another yeast pack?

TIA,
Wes Hunkler

Sometimes there are several reasons for underattenuation. One is simply the type of yeast. Some yeast strains just don't attenuate as well as others. Munton's yeast is known to be problematic that way.

Another reason may be the ingredients. I've had some issues with extract batches pooping out at 1.020 and no amount of repitching made it go any lower. Sometimes there are more unfermentables in a batch (lactose and crystal malt) and while they contribute to OG, they don't ferment out so will leave a higher FG as well. Ingredients like sugar (corn sugar as well as table sugar) will ferment out completely.

As long as you pitch the proper strain and amount of yeast to begin in, another package now wouldn't do anything.

What kind of yeast have you been using?

 

[TheHunk]

It was all dry yeast. Munton's came with the American Wheat. The Ironmaster can had an unidentified yeast in a plain silver packet. For my next brew I will try Fermentis US-05. It seems like the Fermentis packs are much larger, 11.5 grams compared to 6 grams. Thanks for all the help.

 

[Yooper]

It was all dry yeast. Munton's came with the American Wheat. The Ironmaster can had an unidentified yeast in a plain silver packet. For my next brew I will try Fermentis US-05. It seems like the Fermentis packs are much larger, 11.5 grams compared to 6 grams. Thanks for all the help.

Oh, I think you'll like S05. Not just bigger packages, but a nice, clean, well-attenuating ale yeast. I have two batches in primary right now with s05, plugging along nicely at 66 degrees.

Even using kits, it's always worth it to upgrade to a quality yeast even if you're using dry yeast.

 

[eljefebrewing]

Sound like it was dry yeast? If so, I would think that should have been enough. If it was liquid yeast, you should be making a starter.

I see people say this on HBT all the time. I've recently started reading Palmer's book, and he says that one tube of White Labs Liquid Yeast provides approximately 100 billion cells, and is enough to ferment a 5-gallon batch without making a starter. (Small size smack-packs being another story.)

Other than decreasing lag time, why is the standard HBT recommendation to ALWAYS make a starter with liquid yeast?

 

[Yooper]

I see people say this on HBT all the time. I've recently started reading Palmer's book, and he says that one tube of White Labs Liquid Yeast provides approximately 100 billion cells, and is enough to ferment a 5-gallon batch without making a starter. (Small size smack-packs being another story.)

Other than decreasing lag time, why is the standard HBT recommendation to ALWAYS make a starter with liquid yeast?

Because one tube may be enough to ferment a 5 gallon batch, but only if the OG is under 1.040 or so. I rarely make beers that "small". Check out this handy pitching calculator: Mr Malty Go down the page about 1/2 way to find the calculator to help you decide how much yeast you need for a batch. It's pretty eye-opening.

 

[sunblock]

I have had some recent problems like that as well and have tracked them to poor wort aeration. I dont see it mentioned anywhere in the thread yet and a good aerated wort should have a better fermentation. Just one more thing to consider.

 

[WilliamstonBrew]

... And if you don't have well-aerated wort, you'll need the few extra hundred billion yeast cells to make up for the lack of propagation. Hence the use of a starter which bumps up cell counts.

It's my understanding -- after talking to a friend who used to work in a brewery -- that aeration doesn't matter as long as you pitch enough healthy yeast. Fermentation is an anaerobic process, the oxygen in the wort at the beginning is used for the yeast to multiply with, which is an aerobic process.

 

[TheHunk]

I forgot to aerate the Am. Wheat batch but I remembered on the Ironmaster.

 

[WilliamstonBrew]

Do a starter next time, and do it for batches over 1.040 OG. 300+ billion yeast cells will compensate for lack of aeration.

Check out YouTube for lots of useful videos for making a yeast starter.