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Yeast Pitching Rates - Confused...

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zarniwoop

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Hi All,

OK I know this has probably been covered elsewhere but it's getting late in the day and I've already had to deal with a dodgy chilling cube failing on me after the hot wort went in so I'm just going to ask. :)

Up to now I've just been pitching Wyeast 125ml activator packs directly into the wort and so far so good. However I've beeen reading a bit and I'm looking into starters but the advice seems to be conflicting.

The Wyeast website states that for up to 1.060 OG the pitching rate is 6 million cells /ml. However Mr Malty states that it's 11.25 million/ml (at 1.060). So I have 23L irish red ale cooling with an OG of 1.056 so according to Wyeast I should pitch 138 billion cells but according to Mr Malty I should pitch 242 billion cells (0.75million cells x 23,000ml x 14 degrees plato). So why the big difference?

Going by Wyeast I'm only just over the 100 billion they state on the activator packet so I don't even know if I'd bother making a starter?

However going by Mr Malty I have to make one.

Any suggestions appreciated.



Thanks

Zarniwoop
 

sponge

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Think of it like instructions on a kit: Following them will give you beer, although there are better ways to do things.

Directly pitching a smackpack/vial will give you beer (as long as the yeast is not old/mis-handled), although the yeast will not be as healthy as if you were to make a starter.

Directly pitching is more just about doing the minimum, but it's better off to be doing the recommended - as per mr malty.
 

JDW81

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The wyeast pack says you've got 100 billion cells, but that is an unrealistic number. You might have 100 billion if you got it from the factory door, but viability drops with age, transport etc. If you make a starter you can guarantee yeast health and give them the best chance to do the best job they can.

I don't find making starters that much effort and make one irrespective of the beer I'm pitching into (although the style does dictate the size somewhat). For me it is about controlling variables, and yeast health/viability is one that can be easily managed.

JD
 

Nick JD

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I find that I can be wildy out with pitch rates with 1.040-1.060 American Ales and they still taste great.

German wheats, belgian ales and lagers of all kinds ... pitch rate has a massive impact.

Basically, if you're burying your beer under 200g of hops, you can treat your yeast like shit and still get a great beer.
 

zarniwoop

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Thanks for the responses. If I just want to pitch the yeast and not the wort in a starter is it as simple as pouring off the liquid wort and then pitching the yeast cake at the bottom of the starter jar?
 

Nick JD

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Yes. If you make a starter with say 1/5 of a smackpack (25ml) in 2L, then you'll see over a day or two, a thickening layer of wonderful, healthy white yeast piling up on the bottom.

No need to chill it to get it to drop out (and the chap from Wyeast recommends to not put the little feckers to sleep for best results) just decant off as you would a bottle.

I usually leave about 50ml of wort in the bottom to aid swirling.
 

carniebrew

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So how do you work out the number of yeast cells generated by a starter from a split?

Let's say you have a month old Wyeast 3068 that MrMalty tells you is 70% viable...i.e. 70 billion cells. You split it 1/5th, so 1 vial has approx 14 billion.

MrMalty tells you that you need 187 billion cells to ferment a 1.048 ale. How do i get my 14 billion to turn into 187 billion?
 

bum

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Does MrMalty (always sounds so formal) give a volume for your starter?
 

felten

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So how do you work out the number of yeast cells generated by a starter from a split?

Let's
say you have a month old Wyeast 3068 that MrMalty tells you is 70%
viable...i.e. 70 billion cells. You split it 1/5th, so 1 vial has
approx 14 billion.

MrMalty tells you that you need 187 billion cells to ferment a 1.048 ale. How do i get my 14 billion to turn into 187 billion?
Try this calc, I believe it uses the same formula as Mr. Malty, but gives you the option of multiple steps. Just a matter of playing with the numbers until you get what you need.
 

seamad

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I find the yeast calc [ link from felten above] much easier than mr malty. I splilt packs into four so for initial amount enter 25 billion then date of manufacture to determine a more realistic number.

edit. and bum yeastcalc gives starter vol [not sure of mr malty] plus option of stirplate, O2 etc plus lets you do 3 steps which is handy when building up an older yeast.
 

carniebrew

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Brilliant, thanks. That's what was throwing me, there seems to be no inoculation rate/volume on MrMalty's calc...is just says "number of vials or packs needed". Having something where you can put in a starting number is a hell of a lot easier, cheers.
 

micblair

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Im curious to why the growth factor which takes place in the wort (say if you were to under-pitch) isn't considered when thinking about the number of cells required for fermentation? The yeast will always reach its maximal cell count, it's just a question to whether you help it along by building a starter or just leave it, and take a hit on the lag time.

Most of my beers are 1.045-1.050 OG, which isn't too far off the wort concentration recommended for building a starter anyways...so technically why should I bother?

Besides, Chris White in 'Yeast' states you can under-pitch by up to 50% as the widery publicised pithing rates are calculated based on re-pitching from a slurry. Perhaps this answers your question regarding Mr Malty vs Wyeast's calculator.
 

carniebrew

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I finally received my copy of 'Yeast' today (along with 'Hops'), and I skipped straight to the bit about starters for a quick read. From what I've read so far, I think a problem with the 'growth factor' that you can get when under pitching is the taste introduced to the beer when the yeast is stressed from being severely under pitched. So while the yeast may multiply to reach the max cell count as you say, it might make a bit of a flavour mess while doing it? And this is one of the reasons (along with continuous aeration) they suggest to pour off the liquid and pitch just the slurry from a large starter.

Probably no big deal for a mild under pitch, and as mentioned in the book, the flavours imparted by underpitching (down to 50%) are desirable in some styles.

BUT...I have a lot more reading to look forward to...
 

slash22000

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I'd be curious to which styles benefit from underpitching? First I've ever heard of that. If I can make a better beer saving money on yeast I'm all for it. :p
 

carniebrew

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Page 122 of Yeast goes into that. But I've also seen the yeast makers talk about the effects of under and over pitching. Wyeast's page on 3068 is a good example.

The balance can be manipulated towards ester production through increasing the fermentation temperature, increasing the wort density, and decreasing the pitch rate. Over pitching can result in a near complete loss of banana character
 

Yob

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you may not reach full cell count if you under pitch... Yeast need oxygen to reproduce effectively, when your yeast have finished all the oxygen they will start to switch to anaerobic fermentation as opposed to aerobic fermentation.. all (most?) budding occurs during the aerobic stage. Also, if you dont supply enough oxygen for them to complete the budding stage you get unhealthy yeast and possibly spawn petite mutants which have respiratory issues which can often result in under attenuation and poor clean up abilities. This sad yeast isnt good for harvesting and re use.

The best brews are always made with happy and healthy yeast.
 

sponge

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slash22000 said:
I'd be curious to which styles benefit from underpitching? First I've ever heard of that. If I can make a better beer saving money on yeast I'm all for it. :p
Weizens
 

verysupple

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slash22000 said:
I'd be curious to which styles benefit from underpitching? First I've ever heard of that. If I can make a better beer saving money on yeast I'm all for it. :p
Yob is spot on. Underpitching to intorduce certian flavours in certain styles is another one of those "it's all over the internet but no commercial brewer would ever do it" ideas. The reason the big guys don't do it is becuase you don't make better beer by underpitching. You may get some of the desired flavours (i.e. phenol and ester profiles) from the yeast but you are far less likely to achieve proper attenuation and can cause other problems (stressed yeast won't floc as well, are not good for re-pitching, and won't clean up the nasty stuff they produced earlier). You are far better off controlling your fermentation temperature to achieve the phenol and ester profile you want.

If you don't have good temp control and want to try adjusting pitch rates to control your flavours then you're ambitious....but will be disappointed. Without temp control you kind of have to suck it and get whatever you get because the temperature will have a much greater effect on the flavour than the pitching rate.
 

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