Overpitching Yeast

[Obadiah Boondoggle]

Looking for views please on why you should not over pitch yeast

 

[Slid]

Problems are said to include over-attenuation and lack of esters, which can be produced in greater quantity with a slight under-pitch.

 

[Alan_Reginato]

This article suggests that occurs an increase in diacetyl for high pitch rate. [PDF] Impact of pitching rate on yeast fermentation performance and beer flavour | Semantic Scholar
The threshold should be around 100 ppb, and with 40x10^6 cells/mL in a lager, hit 307 ppb.

I usually pitch 5x10^6 cells/mL, with dry yeast. That's the minimum suggested by Brewers Friend calculator. For 0.35M cells / mL / °P

Maybe with 1 L slurry for 20 L wort, could get 50x10^6 cells/mL.

Thinking about, I just realized that my last batch, that I used the yeast cake from the previously one, hit that number. I didn't notice anything that seems to be an off flavour. But it's something to care about next time.

 

[Hazelwood Brewery]

Looking for views please on why you should not over pitch yeast

What are you trying to achieve by over-pitching?

If you’re looking to shorten fermentation time for example you might want to consider the yeast you use, the temperature you ferment at, or prepare a starter to reduce lag time and increase cell count.

 

[Obadiah Boondoggle]

What are you trying to achieve by over-pitching?

If you’re looking to shorten fermentation time for example you might want to consider the yeast you use, the temperature you ferment at, or prepare a starter to reduce lag time and increase cell count.

My question wasn't to try and achieve anything in particular

It's just I have read "don't under or over pitch"

I understand the under pitching consequences but not so sure on over pitching

 

[Hazelwood Brewery]

My question wasn't to try and achieve anything in particular

It's just I have read "don't under or over pitch"

I understand the under pitching consequences but not so sure on over pitching

Understood I also sometimes just want to know stuff.

 

[Cheshire Cat]

I'm currently brewing a Munich Helles with CML Hell yeast. Last time I made it I pitched two packets and fermented at 12C as per the instructions on the packet. It turned out very good. I intend to do the same today.

 

[Obadiah Boondoggle]

This article suggests that occurs an increase in diacetyl for high pitch rate. [PDF] Impact of pitching rate on yeast fermentation performance and beer flavour | Semantic Scholar
The threshold should be around 100 ppb, and with 40x10^6 cells/mL in a lager, hit 307 ppb. View attachment 42566

I usually pitch 5x10^6 cells/mL, with dry yeast. That's the minimum suggested by Brewers Friend calculator. For 0.35M cells / mL / °P

Maybe with 1 L slurry for 20 L wort, could get 50x10^6 cells/mL.

Thinking about, I just realized that my last batch, that I used the yeast cake from the previously one, hit that number. I didn't notice anything that seems to be an off flavour. But it's something to care about next time.

Thanks, Alan

Really useful article

 

[aamcle]

Unless you're brewing something that requires under pitching yeast to deliberately stress it homebrewers are hardly likely to have a problem. Commercial breweries use vast amounts of yeast and make good beers.
If you ask here, may need a new thread, about pitching on the Yeast cake you will find few problems or off tastes reported.


Aamcle

 

[Tom Archer.]

As a newbie, pitch rates are a subject I've been struggling to make sense of, and after reading everything I can find about it, find myself drawing some tentative conclusions - but do please shoot me down if I'm getting this completely wrong..

Under-pitching and very extreme over-pitching, would seem to run the risk of introducing some negative flavours into the brew, whilst over-pitching, up to perhaps tenfold, will tend to cause flavour change, depending on the degree, but within a broadly positive spectrum.

Thus for the home brewer for whom every brew is a new adventure, it would seem wise to pitch big and not worry too much about exact yeast counts, whereas for the commercial brewer, whose customers expect each batch to taste the same as the previous one, cell counting needs to taken seriously.

Observing the routine for counting yeast cells also suggests that a more accurate figure will probably be gained from sampling cold crashed slurry than a dynamic starter brew. It follows that when batch consistency is sought, it may be better to count the cells going into the starter rather than the cells going into the brew, with the routine for culturing the starter tightly managed to give a consistent bulking up ratio.

That latter point is very tentative however, if I'm missing something, do please tell me!

 

[Agentgonzo]

Thus for the home brewer for whom every brew is a new adventure, it would seem wise to pitch big and not worry too much about exact yeast counts, whereas for the commercial brewer, whose customers expect each batch to taste the same as the previous one, cell counting needs to taken seriously.

I pitch one sachet for all brews, but two if it's a high gravity beer. Whilst there may be perceptible differences in the end product, they are probably tiny, of 5 perceptible at all. Consistency isn't important to me as I rarely repeat a recipe.

More yeast will also ferment quicker and how long it takes to ferment is probably also important to commercial breweries. But it doesn't matter a jot if I have to leave mine in the fermenter an extra 1/2 weeks for it to finish due to an underpitch.

 

[Birdsnestbrewery]

I pitch one sachet for all brews, but two if it's a high gravity beer. Whilst there may be perceptible differences in the end product, they are probably tiny, of 5 perceptible at all. Consistency isn't important to me as I rarely repeat a recipe.

More yeast will also ferment quicker and how long it takes to ferment is probably also important to commercial breweries. But it doesn't matter a jot if I have to leave mine in the fermenter an extra 1/2 weeks for it to finish due to an underpitch.

I agree. If you are doing standard 20-23 litre batches and not making extra strong beer (eg. Up to 6-7% abv) a single sachet of dried yeast will be fine. No starter required.
If you're using liquid yeast it may be more critical, I don't use it very often so don't have an opinion.

 

[MashBag]

I agree. I will be as bold as to say that I have said to new brewers "don't sweat the small stuff - let's make beer and make you grin".


There is no one way, so the reading/chemisry/famous debatables come later, once you see what you want.... Through a glass of beer.

 

[.Peter.]

Try this calculator : Pitching rate calculator | Lallemand Brewing

 

[MrJay83]

I've noticed that Brewfather always recommends something like 2-2.5 packets of yeast but when I look at the manufacturer's pitching range I'm always within it (usually towards the lower end). My beers come out fine.

 

[hoppyscotty]

I suspect we're all either under-itching or overpitching yeast. The chances that you're hitting the correct amount based on your calculators and assumptions about viable starting yeast populations from your packets and liquid viles that have been sat on several warehouse shelves at unknown temperature, transported between various places exposed to varying temperature conditions etc. The only way to be sure is to set yourself up a small lab area and get a microscope and actually count cells...that is what the larger more serious breweries do.

I suspect the window is quite wide and to get any noticeable negative impacts you have to be either heavily under or over pitching.

For example for 2 years I was being predominately brewing from 19litre all grain kits that always came with one packet of dried yeast or one vial of liquid yeast to make a 2 litre starter with and all the resulting beers were fine with no off flavours anyone could detect and turned out very nice indeed. I've since started using pitch rate calculators that say I have been underpitching all this time so have adjusted and am now over pitching slightly for the convenience of using 2 packets of yeast instead of 1.5 packets, and I cant really say I've noticed a difference. So either my overpitched beers are just as 'flawed' as my previous unerpitched... or it doesn't really matter at least at these small batch volumes.

 

[Birdsnestbrewery]

I suspect we're all either under-itching or overpitching yeast. The chances that you're hitting the correct amount based on your calculators and assumptions about viable starting yeast populations from your packets and liquid viles that have been sat on several warehouse shelves at unknown temperature, transported between various places exposed to varying temperature conditions etc. The only way to be sure is to set yourself up a small lab area and get a microscope and actually count cells...that is what the larger more serious breweries do.

I suspect the window is quite wide and to get any noticeable negative impacts you have to be either heavily under or over pitching.

For example for 2 years I was being predominately brewing from 19litre all grain kits that always came with one packet of dried yeast or one vile of liquid yeast to make a 2 litre starter with and all the resulting beers were fine with no off flavours anyone could detect and turned out very nice indeed. I've since started using pitch rate calculators that say I have been underpitching all this time so have adjusted and am now over pitching slightly for the convenience of using 2 packets of yeast instead of 1.5 packets, and I cant really say I've noticed a difference. So either my overpitched beers are just as 'flawed' as my previous unerpitched... or it doesn't really matter at least at these small batch volumes.

All of which suggests that actually, we're not actually underpitching or indeed overpitching, despite some sources suggesting otherwise.
It's biology, not everything is exact.
Of course there are some who would love us to use two packets instead of one, "just in case"... Just saying

 

[Stu's Brews]

Based on my personal experiences pitching the right amount of yeast can have a significant impact on the final beer. However, what constitutes under- or over-pitching can vary depending on beer style. Rough guideline values for pitch rates are as follows:

• Ales - 0.75 million cells / ml of wort
• Hybrid - 1.0 million cells / ml of wort (this covers styles like modern IPAs where a cleaner fermentation profile is desired)
• Lagers - 1.5 million cells / ml of wort

Before I started worrying about pitch rates I was certainly below 0.75 million cells / ml (for a standard 20L batch that will almost always be the case if you are pitching a single packet of yeast), which runs the risk of excessive ester, fusel alcohol and other off-flavour compounds as well as poor attenuation. I definitely noticed a reduction in fusel / phenolic flavours in my beers when I started pitching yeast at the above rates.

I've never knowingly pitched more than the above rates, however, I have brewed the same beer (a Golden Ale using London Ale III) using an 'ale' and a 'hybrid' pitch rate and noticed a significant change in the ester profile in the final beer as well as higher attenuation. For that particular beer I felt the 'ale' pitch rate resulted in a better beer, therefore it could be said I 'over-pitched' even though there were no off-flavour consequences.

The other thing to bear in mind is that pitch rate is only one part of the equation; you need to make sure you have healthy yeast too.

(Caveat based on above posts that I don't actually know the exact amount of yeast being pitched so rely on the output of my yeast pitch rate / starter calculators to estimate how much yeast I actually use).

 

[MrJay83]

All of which suggests that actually, we're not actually underpitching or indeed overpitching, despite some sources suggesting otherwise.
It's biology, not everything is exact.
Of course there are some who would love us to use two packets instead of one, "just in case"... Just saying

Yeap. A second pack of yeast will add up to a 15% extra cost of my ingredients in a brew.
Seriously starting to think about harvesting but don't think my wife would appreciate it in the fridge

 

[Agentgonzo]

Yeap. A second pack of yeast will add up to a 15% extra cost of my ingredients in a brew.
Seriously starting to think about harvesting but don't think my wife would appreciate it in the fridge

Would a starter be cheaper?