Double batch pitch rate

[Swags]

I read an older thread on double and triple brews into the same fermentor and did not come up with a consensus on pitch rate.

Most responders seemed to say pitch the full amount of yeast required for the double brew after the first brew, but one guy said he pitched only enough for the first brew and then topped off the fermentor with the second brew w/o adding additional yeast.

Appreciate any comments.
thanks

[gitchegumee]

Depends...

Depends on how long between successive pitches you are. I pitch for a single fermentation the first day, and then knock out a second batch on top of that 24 hours later. I cannot tell the difference between fermentation performance, nor with taste of resulting beers made by single fermentations compared to double-batching.

I read an older thread on double and triple brews into the same fermentor and did not come up with a consensus on pitch rate.

Most responders seemed to say pitch the full amount of yeast required for the double brew after the first brew, but one guy said he pitched only enough for the first brew and then topped off the fermentor with the second brew w/o adding additional yeast.

Appreciate any comments.
thanks

[dick murton]

For brews in close succession, i.e. the same day, it is common practice to pitch sufficient yeast into the first brew for both the brews. Aeration / oxygenation is then carried out at the standard rate for both brews. I have come across FVs which are filled with up to 12 successive brews, and the later brews had reduced or nil oxygenation to reduce yeast growth and adverse palate effects. Certainly al the big companies I am aware of (and having worked for a fair few over the years..) pitch once and add wort only afterwards - for reasons of yeast growth / flavour characteristics consistency.

If you are collecting and re-pitching from the saved yeast, then it is generally considered better to pitch once only, in the first brew, because then all the yeast is the same viability / vitality and age. You may need to reduce the aeration / oxygenation of the second brew to prevent too much reduction in ester production. You shouldn't have a problem with diacetyl when adding wort this early in fermentation of the first batch. If you add yeast food such as zinc chloride or sulphate, then add this pro rate per wort batch.

Having said all of that, if it produces what you consider are better results by splitting the yeast, or perhaps you don't reliably have all the yeast available at the time of the first brew, then go ahead. Phillip is obviously happy with the way he has refined his operations and with the beer quality produced. I suggest though, that whichever route you follow, you follow it consistently, and don't vary the process for a particular brand, to ensure greater consistency within that brand. If you want to have different process for different brands, fine, but just remember how easy it will be to make a mistake, especially if you have a number of people working with / for you.

[Junkyard]

+1 for pitching for both batches when they are in close succession (4-8 hours of each other)