Pitching rate

[Jake]

This may have been discussed before, but after a discussion last week it came to my mind that I may be underpitching. Been doing some reading, and according to Mr. Malty, probably the most trusted source when it comes to pitch rates, if I'm doing a 5 gallon batch at around 1.055, it requires 200 billion yeast cells.

Up to this point, I've never pitched more than 1 package in a 5 gallon batch, so I'm realizing that I'm hugely underpitching, considering each pack of SO5 is good for only up to 100 billion yeast cells according to the manufacturer. I'm going to do a batch this weekend and use 2 packs (of a beer I've previously brewed)... how much of a difference do you think this should make?

This is my first time checking out the Mr. Malty website, and just through reading through most of the material, I feel I've learned alot. If you haven't done so, I'd recommend.

Do most of you use 2 packs of dry yeast? I'd imagine that this would be stressful to the yeast, so I'm hoping to see an improvement. I also have that new stirplate, so planning to also do my first starter this week with some liquid yeast on Sunday. Looking like a busy weekend.

[Chris Craig]

I've never pitched 2 packs of dry yeast in a 5 gallon batch before. This is on of those topics where everybody has an opinion, but almost no way of backing it up.  I think even if you made a 10 gallon batch, split it into to carboys with 2 packs in one, and 1 in the other, you'd have your best chance of determining any difference.

[JohnQ]

Well, my IIPA had an OG 1.085, Single Pack of S05 and fermented down to 1.015 in a couple of days...
Still waiting for the Geeksquad to chime in, but it certainly didn't seem necessary there.

JQ

[sdixon]

I have done both, pitched dry yeast and 1.5 L starters and have not been able to tell the difference. I'm sure there has been differences, but my palate cannot discern. I usually make starters because I am using slants or repitching.

[Jake]

Yea on the site it did say that for regular starters without a stir plate you require a 2+ liter starter. If using a stir plate a 1 liter starter will do. It does seem that the beer will ferment out to low FG's but it says that it's more stressful for the yeast and this will show in the product.

Come to think of it, I've only done 2 batches above the 1.070 range and both never tasted quite like I was expecting. May have been the strained yeast possibly? Either way, I'm going to give Mr Malty's recommendations a try bc it seems to be what most swear by.

Are starters possible with dry yeast or is rehydrating the only option?

[fakr]

Personally, for a 5-6GAL batch with an OG under 1.075 I use 1 pack.  
If it's over 1.075, I typically make a starter with 1 pack of yeast.
I only pitch 2 packs in a 10-12GAL batch.

[Richard]

(Geek squad here)

I'm thinking this would be a good experiment for the next meeting of the IPS -- do a higher-abv batch (say... 1.080) and pitch one with half a pack and the other with two. Take notes on how long the lag phase is (higher with lower innoculation count... could lead to infection), how vigorous/fast the fermentation is (higher with higher innoculation... supposedly produces a clearer beer and blows off volatiles better), and ultimately how the final product tastes (lower pitching = larger ester/phenol profile, more hydroxyl acid precursors which will produce VDKs such as diacetyl, and a greater oxygen requirement which will if left untreated lead to greater acetaldehyde production).

As for me; I have some recipes which seem to defy the logic. Black Like Your Heart got stellar reviews from people and at 1.070 is a rather "big" beer. I only ever pitched a single pack of yeast into that, and not rehydrated, which should mean it would be around a half a pack viable. By the numbers that's a serious under-pitch, but the beer has been great.

The scientist in me looks rather disdainfully at the idea that every strain of yeast would have the same "optimum" pitching rate; or every recipe of the same gravity for that matter. Personally; I feel that this is a recipe issue. Pitching rate is another parameters you have a handle on, or can tweak, in response to what you perceive to be a defect in a particular beer. If the beer tastes good - drink it - and keep pitching the same, unless you have a problem hilighted above. The purists will no doubt rally against such anecdotally-motivated advice, but screw them - it's your beer.

My "hunch" is that S-05 has a lower pitching rate requirement than other yeasts.

fwiw, if anyone wants some seriously good reading on this, check out Yeast: The Practical Guide to Beer Fermentation.

[Kyle]

with a 5g batch above about 1070 O.G. I do tend to pitch two packs since there is alot for them to chew on, but otherwise not. I'll need to read up on it more, but Jake, your beer is very good, so I doubt there is a problem with your current pitching rate.

Edit: the reason I use two above that OG is I notice a significantly reduced lag time of several hours to a day before active, churning fermentation

[Jake]

Yea my lower OG beers have been pretty good, but as soon as I go up above 1.050, I find that there's something off. IPA's and hoppy beers aren't all that bad, but I recently did a couple beers in the 1.060-1.070 range with less of a hop presence, and there's a similar off flavour in both of them that I can't pinpoint ... I'm thinking after doing some reading last night that it could be due to the underpitching; not to mention I'm fermenting around 16 degrees celcius, so this makes it even worse requiring more yeast cells.

I'm not having any problems with getting my FG down below 1.015, but I'm thinking that the yeast is putting off some weird off flavours from not having enough cells present.

[Richard]

Can you describe the off-flavour?

[Jake]

I'm having a hard time thinking of a description for the taste off the top of my head ... I can't get bback to you on that one until after the weekend either bc I'm away for work.

I attributed it to the yeast mostly because it was something I was seeing with higher OG beers, but maybe a coincidence.

[Richard]

I think your intuition is correct, given the circumstances you described.