Double Batch Fermentation Schedule

[DaveVonRenn]

Hi everybody,

First time here, so a little background. I brew at my Landgasthof (it a beer garden/restaurant) here in Bavaria, Germany. I did some pilot brews of 30L and have since scaled them up to have as mainstays on our tap. I have recently begun double batch brewing since you can produce more as demand is growing here.

I just did my first double batch of an American Blonde Ale. On the first day I brewed Batch 1, oxygenated and pitched enough for Batch 1 only. However, I oxygenated the Batch 2 on the second day and topped up Batch 1 in the FV. I hit all my numbers and temp control was spot on. The final beer had a slight fruity note to it in comparison to the first pilot batch (most customers really enjoy it saying it tastes just like the first (maybe that is me being too critical)). Could this have been caused by the oxygenation of Batch 2?

I have since done two more double batches (they are both still in the FVs). However, this time, due to time constraints as I am really only a part-time brewer, I had to brew Batch 1 on Wednesday and Batch 2 on Friday (so 48 hours in between) during high kräusen. Both fermentations have been strong. My question here is: Can you brew a double batch with a day in between? So Batch 1 on Monday and Batch 2 on Wednesday?

Finally, should I pitch for full volume of both batches with Batch 1, or can I pitch for Batch 1 only?


Thank you for your help!

Dave
BierCraft HandwerksBrauerei
Hammelburg, Germany

[Junkyard]

Dave, for double batches you ideally want to brew them both the same day. If you brew the second any more than 12 hours after the first it is a risk to oxygenate because the yeast from the first batch has likely already entered anaerobic fermentation phase after using all the oxygen to replicate. Adding more oxygen likely will confuse them, making them re-enter growth phase and thereby create more esters. The fruity ester you describe in the beer was likely created during the growth/replication phase and was likely noticeable because only enough yeast was pitched for the first batch.

I would recommend brewing both batches on the same day. Pitch enough yeast for both batches, and oxygenate for both batches. That should give you solid results.

[pcollins]

We will brew our 1/2 batches a day apart. Pitch enough yeast for full tank day one, oxygenate day one only. Day two just straight in to the tank, no oxygen.

We're brewing 11.5hl each 1/2 batch into 25hl fermenters.

[Sheets22]

We do triple batches over the course of 24-28 hours and oxygenate each batch with no problems. 48 hours would probably be pushing it though, especially for something as low gravity as a blonde ale, i would imagine you're well beyond 60% attenuation by then. If you have to do it that way, maybe just skip the o2 on the second batch to be safe.

[DaveVonRenn]

Thanks for the reply.

I realized that oxygenating Batch 2 was a problem after brewing and reading the forums here...

Double batch brewing on the same day would be ideal. However, I have severe time constraints, so brewing two days in a row seems to be, for now at least, my only option for filling the FV.

If I do two double batches, should I do them one day right after the other? Or is a day in between not a problem?

Also, should I pitch only for Batch 1, adding Batch 2 without yeast the next day, or for Batch 1 and Batch 2 on day one?

I have been reading over many threads and there seems to be quite a difference in opinion and procedures at many breweries.

Thanks.

[Sheets22]

We just pitch enough for batch 1 with plenty of o2, it will prop up plenty overnight. Then we brew batch 2 early the next morning with o2 but no added yeast. I've noticed it won't dry out as well without the extra dose of o2. Again, i really wouldn't risk oxygenating more than 24 hours after your first pitch

[DaveVonRenn]

I decided to at least summarize what I have found from other posts that concern double batch fermentation.

1.) It is best to do a double batch fermentation on the same day, if possible, adding the full volume of yeast to Batch 1 and oxygenating Batch 1 and Batch 2.

2.) If it is not possible to do this, doing back-to-back brew days is best, where Batch 1 is oxygenated on Day 1 and Batch 2 is not oxygenated on Day 2.
Here opinion splits.
- Either add the full volume of yeast for both batches on Day 1 with Batch 1
or
- Add the correct amount of yeast for just Batch 1, which will act, in a way, as a starter for Batch 2.

This is what I have found and as opinions differ, I guess the best route is trial and error, seeing what works best on your own system.

Thanks for the input from those above!