secondary fermentation by adding new wort

Ingredients
1

I’d be curious to hear some experiences of having done a primary fermentation until it’s essentially completed (or close to it), then adding a considerable amount of new wort (similar to the original, already fermented wort) to kickstart a new phase of secondary fermentation.

Pros, cons?

Here’s what provoked the musing:

I’ve started a series of experiments in which I brew a batch with a given recipe, but then split it into 6-9 small FVs (roughly a half gallon each), each with a different yeast.  The idea was that a couple of months down the road, after sampling a flight of these ‘limited release’ sub-batches, I can then decide which yeast(s) to use next time I do that recipe, and do a larger batch.

But perhaps after 14 days of fermentation, I could sample the early beers as they’re mostly done fermenting, and if some stand out as clearly superior to the others, I could then add another couple gallons of new wort to those, right ion the same yeast slurry bed – essentially a secondary ferm in the same vessel without transferring (and of course, trying to minimize oxygen ingress).

Anybody have some experiences [/mishaps] with that, or have advice on things to watch for (or not do)?

2

I guess I’m not sure what the pros are except adding an extra step.

3

German breweries do this for carbonation (Speise) but in the volume you’re talking about I would worry about the fresh, oxygenated wort impacting the fermented wort negatively.

4

If you think you are saving on yeast then just rack it off, brew a new batch and pitch the saved yeast slurry.

5

Thanks guys.  You’re right, there’s no apparent advantage vs racking off the old and starting a brand new one.

Like editing a document one has written, it’s helpful to have a fresh set of eyes take a look at it to help see what you’re blind to, despite it being right in front of your face.  Your feedback makes perfect sense, and is appreciated.

6

It does kind of remind me of a solara. This is a technique borrowed from rum production in which a portion of finished beverage is pulled out and a new portion is added. Some sour brewers have used this technique. Usually they are relying on the souring organisms to sour the fresh “pitch” of new fermented beer but it could be done with wort I guess if there was a way to dump yeast from time to time.