Yeast quantities per brew.

[Alex.mc]

I'm reposting part of another thread here as it's probably the more appropriate place.

I split a brew yesterday, so I could add some aroma and flavours to a small part of the batch.
I brewed 23 litres from an all grain ingredient kit. I split off 4 litres at the end of the boil into another smaller stockpot, and did the last 10 mins with the added ingredients.

The 10g sachet of yeast was divided by percentage for the larger and smaller portions, each one in it's own fermeter, and the yeast pitched.
So the same amount of yeast for the full volume has gone into it's appropriate volume. I can measure to 0.1g so am confident they are pretty accurately measured out.

I see comments where people say they have added a second sachet "to keep things moving" etc.... and wondered what the deal was with yeast volume versus wort volume?

Is there a minimum volume to be "enough" to get things started? And anything over is just insurance? Per volume of Wort that is? Is it pointless adding way over the recommended amounts? What is the recommended amount?

 

[peebee]

There is a "minimum volume", or cell count, to get fermentation going in a decent time. There are lots of calculators to work out how to achieve this (starter volumes, etc). If the cell count isn't high enough much of the yeast spends time growing and not fermenting (and for this the yeast needs access to oxygen). You will need higher cell counts for higher gravity beer. But this is all relevant to using liquid yeasts. For dried yeast they are prepared to directly pitch into the volume it says they are good for on the packet.

A bit too much yeast will produce a "cleaner" finish and is favoured in (e.g.) the US, a bit too little yeast puts the yeast under stress and more likely to create "flavours" - this might be favoured in the UK.

You are using dried yeast so just go with the packet instructions and keep within the best before date.

Adding a second packet? That is about as creditable as the comment "to keep things moving" is concise.