So I recently made the switch to AG brewing from extract. Santa brought me an Anvil.
I’ve made yeast starters for my last two batches. Both 1500ml in volume on a stir-plate.
Tonight I was doing a little reading about yeast and making starters and discovered that I
should have chilled the starters after 24-36 hours and decanted the wort off the yeast bed.
My question is, since I pitched the entire 1500 ml into the fermenter, how much of a negative effect is that going to have on the finished product?
To be clear, both batches are still in primary. One is a Alaskan Amber clone and the other is a dunkelweizen.
Both starters were made with a amber DME.
Adding 1.5 L of very oxidized beer to your batch certainly didn’t improve the batch but it didn’t ruin it either. The impact will depend upon the size of your batch of beer. As you noted, when making a yeast starter on a stir plate (or anytime you let the starter ferment to completion), it is best to decant most of the beer and pitch the remainder.
Some homebrewers make a smaller volume starter, around 1 L, and then pitch the whole thing while it is actively fermenting.
I think the concern is that the oxidized starter wort has off flavors that won’t go away. That being said, my stirplate starters (when I use a stirplate still) don’t smell or taste oxidized.
Oxidized material has already taken the free O2 and combined it chemically with something. You would not get any free O2 from adding something oxidized. For example, oxidized hydrogen is water. Adding water does not give oxygen to the yeast because it is bound up in the water molecule.
I went through the same process, and it always bugged me putting spent starter in the fresh wort. Eventually I came up with a process whereby I decant the starter(s) about 20 minutes before flameout and put fresh chilled wort (from my Thermonator) into the flask(s) and put them back on the stir plate until I’m ready to pitch the yeast.
I don’t know if all these shenanigans make a difference, but they make me happy, and in the long run that’s the same thing.
We always pitch the entire contents. The harvested yeast from the previous brew was always fed with fresh sterile wort. It never failed to produce awesome beer.