Please chime in on your best result for yeast pitching rates.

[William Grote]

I searched the archives but could not find a specific thread, so I beg your collective indulgence (or forgiveness if this has been covered.)

Between the beer nerds and the wine nerds (nerd is a compliment) there is an encyclopedia of info on the proper pitching rate for each style and species of yeast, how to tease Torulaspora delbrueckii , for example,  to get more clove for your Hefeweizen....  but not so much for cider.

Can we collectively pool info for cider since as far as I can tell, the knowledge is sparse on pitch rates for inoculated yeast.  What matches wild fermentation rates?

The size of the yeast packets available for most hobby / home cider makes is between 5-8g with a recommended dose of approx 1g per gallon.  Why?  Since that's what home beer makers and wine makers use?

Grape juice has 2-3 times more sugar than apple juice.

Wort, aside from having levels of unfermentable sugars, which the brewer can control, can be manipulated by under-pitching or over-pitching to coax different flavor and aroma results from the yeast.  

But what about cider?

I assume an ideal pitch rate, based on juice Ph, TA and SG  could help better control fermentation speed.

I ask this, since I have found that 'underpitching' drastically slows down fermentation and at least in my experience this season, is preserving flavor and aroma.

Food for thought

William

[Andrew Lea]

On 08/01/2017 05:10, William Grote wrote:

> I assume an ideal pitch rate, based on juice Ph, TA and SG could help
> better control fermentation speed.

FWIW, when I was at Long Ashton back in the 1970's, our standard
pitching rate for both cider and white grape wine was to achieve 5 *
10^6 cells / ml in the sulphited juice. Independent of pH, TA and SG.

Andrew

--
near Oxford, UK
Wittenham Hill Cider Portal
www.cider.org.uk

[Andrew Lea]

For comparison, I should have added that the typical overall cell count of wild yeasts in a UK cider juice after pressing but before sulphiting is around 10^4 to 10^6 cells / ml. The Saccharomyces count may be from 10^2 to 10^4 cells / ml. Hugely depends on fruit condition and history.

Andrew

Wittenham Hill Cider Portal
www.cider.org.uk

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[Claude Jolicoeur]

Consider also that the pitched yeast will only be a small fraction of the total yeast population once the population growth is completed.
You may evaluate yeast population either in number of cells per mL as Andrew writes, or as the weight of yeast biomass.

Here is a little bit of basic yeast arithmetics...
Standard yeast pitching recommandation is 25 g per 100 L (i.e. one 5g packet for 20L). This is 0.25 g/L of yeast biomass.
In 1 g of yeast biomass, there are approximately 15 to 20 billion cells, hence 1 g/L of biomass means 15 to 20 million cells par mL (15 to 20^6)
So you can see the standard pitching rate of 0.25 g/L corresponds to 4 to 5 million cells per mL (4 to 5^6 cells/mL) as Andrew said.

Yeast-nutrients relations:
Yeast biomass contains approximately 10% nitrogen.
Hence, if the juice contains 100 ppm of YAN (or 0.1 g/L), this amount of nutrients will permit building 1 g/L of yeast biomass. Add to this the pitched rate or 0.25 g/L, and you get a maximum total biomass of 1.25 g/L, corresponding to approximately 20 to 25 million cells per mL.
You can see here that the peak yeast population will be much higher than the pitched rate, and will vary a lot with the available assimilable nutrients (YAN).

Claude

[Andrew Lea]

On 08/01/2017 17:33, Claude Jolicoeur wrote:

> You can see here that the peak yeast population will be much higher than
> the pitched rate, and will vary a lot with the available assimilable
> nutrients (YAN).

This is a very important point. Some people seem to imagine that yeast
cell numbers somehow stay constant during fermentation. They don't, of
course. They are living things and they multiply as much as nutrients
and other fermentation conditions will allow them.

[William Grote]

Happy New Year Andrew and Claude

Thanks for the advice and info as always.  This was great timing, I have been over-pitching my batches and I think that might contribute to the excessive fermentation speed of some of them this season.  The yeast packets from MoreWine are all 8 gram each.

Cheers

William

[Miguel Pereda]

To check the number of yeast / mL present you can also use a x400 magnification microscope and a Neubauer camera. It is fairly easy to use and if you use methylene blue you can check the rate of live yeast.

Miguel A. Pereda