Pitch more yeast on high gravity?

[Trails_n_Ales]

How's it going? I brewed an imperial stout yesterday and my OG is 1.08. I used 1 vial of white labs irish ale yeast and was wondering if more yeast is necessary for a high gravity beer like this? I have a packet of Danstar nottingham yeast, would this be ok to pitch with the irish ale?

 

[aprichman]

You should target 10^6 yeast cells per mL per Plato

 

[porterpounder]

Yes, a beer that big usually requires a good starter with a couple step-ups or a good starter with a couple packages of yeast. Yes you can pitch the dry yeast, but it may change the character of the final beer. Then again, it may not and be just what you wanted.

 

[CJ-3]

To know how much yeast you need to use, a yeast calculator comes in handy. There are a bunch of free ones online, and here is just one example.
http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

The calculators take into account your projected oG as well as how old your yeast is, which is very important for determining how much you need.

 

[Queequeg]

Yes you need more yeast for an impy, 1.080 isn't too high. Still ideally you should have made a starter.

If you don't pitch you may get underattenuation and possible off flavors, if you pitch notty you may lose some of the character from the Irish ale yeast since notting is pretty fast fermenting and fairly neutral.

Personally I suspect you have underpitched significantly, so I would put the notty in, since you may find you will need to pitch it anyway later and muted esters are better than diacetyl

 

[Hoofer]

Depends on how big a batch you pitched it in. For 2.5 gallons that probably ok. Anything more you underpitched. I dont use dried yeast and always make a starter so I dont know how many cells are in a dry packet. But for a 5 gallon batch of 1.080 I would pitch a healthy slurry of 2.5 to 3 billon cells.

 

[Juno_Malone]

The best thing to do is use one of the many yeast calculators out there (I like Mr Malty's: http://www.mrmalty.com/calc/calc.html) to calculate how many cells you need for a healthy pitch, and go from that. My general rule of thumbs are:

When using dry yeast, I'll use one pack up to 1.070 for 5.2 gal of wort.

When using liquid yeast, I'll pitch straight up to 1.050 or so, for 5.2 gal of wort. Any higher than that, and I'll make a starter.

But these are just general rules of thumb, and also depend on the age of the liquid yeast, and whether or not I'm OK with a slight underpitch depending on the beer I'm brewing.

 

[mightynintendo]

How's it going? I brewed an imperial stout yesterday and my OG is 1.08. I used 1 vial of white labs irish ale yeast and was wondering if more yeast is necessary for a high gravity beer like this? I have a packet of Danstar nottingham yeast, would this be ok to pitch with the irish ale?

You can easily convert OG into an estimated °Plato with a simple equation:

Where G = gravity being tested

°Plato = -616.868 + 1,111.14G - 630.272G² + 135.997G³

1.08 OG ≅ 19.33 °Plato

And as stated before, 1 million yeast cells per degree plato per mL.

OPINION: This is a middle ground number actually. You can pitch ales at 75% of this number and should pitch lagers at 125% of this number.

A quick reference for gallons to mL:

1 gallon = 3,785.41 mL

5 gallons = 5 × 3,785.41 mL = 18,927.05 mL

And putting it all together:

(1 × 10&#8310 × 18,927.05 × 19.33 = 365.86 Billion Yeast Cells

1 vial of white labs yeast has how many cells? 100 billion? if so, then you under-pitched a five gallon batch by a considerable margin.

 

[Queequeg]

@ mightynintendo good post, I would like to add pitch rate should also depend on yeast, style and gravity. Typically English ales are pitched at 0.35-0.5, us ales and farmhouse ales 0.75-1, imperials and barley wines 1-1.5, larger 1.5 and lambics very low

 

[Likefully]

If fermentation hasn't started yet give it a very good shake a few times over the next 12 hours or until you can see fermentation has started.

I haven't added extra yeast after pitching before, but i would imagine if you are going to add the Notties do it soonest otherwise the opportunity is lost.

 

[Trails_n_Ales]

I pitched the nottingham and also a smack pack of american ale yeast. Took a hydrometer reading and im at 1.02. Seems to be ok. Not sure if i disrupted anything that could cause off flavors though.