Of course if you re-pitch the dry yeast on a subsequent batch, it really is a pitching of liquid yeast, so O2 would be suggested, as with any liquid yeast.
Just a clarifier on O2 use in that circumstance…
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My take isn’t worth a tun. 34/70 is all that’s stated. It just isn’t my favorite. I’ve had great luck with s-189 and s-23. I only make a lager spring and fall. I’ll do. 20g batch twice a year. I also do a lot of ambient ferments with them. I have an unheated space and the ferments stay around 55-60 when you hit it right. They end up quite good and do well in comps for such a simple way to brew. I always use 6 sachets for each batch split 11g to each fermenter. Cold crash it, keg and go. I do wish I liked all the other dry yeasts. So darn easy when doing any lager. Sometimes I’ll throw in 021 Kolsch yeast as part of the split. I just pull it to the warmth if things chill. I’ll say that as long as I can get 189 and 23, too easy for me to grow a starter. Everyone does it different, that’s the best part of it.
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I used 34/70 a lot and always get good results,
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Yeah, whatever issue the OP had, it’s not the yeast itself causing it.
Has it happened more than once?
I’ve had two batches fermented with 34/70 that had an off taste that I perceived as green apple and attributed to Acetaldehyde. My understanding is that there are many potential causes for Acetaldehyde. But I haven’t had it in any of the other beers I’ve brewed. Nor have I had it in any 34/70 batches that I’ve oxygenated.
I love 34/70, and I’m not blaming the yeast for anything. I only bothered posting about my experience in case it was relevant to anyone else. Note that two posters on this thread complained about lemon/tartness flavors with 34/70. I thought our experiences were perhaps similar.
If it makes no sense to oxygenate dry yeast, then it makes no sense. My personal experience is not statistically significant. But I’ll keep doing it until my own experience changes my mind. Sort of like blowing on dice to get them to come up sevens, I guess.
I haven’t seen anyone advise against oxygenating with dry yeast. In my opinion, I don’t think you have to.
I question how long the O2 will stay in solution before it can be used by the yeast. I’ve heard 45 minutes to 6 hours. Dry yeast already has the benefits of oxygenation built up in them … So by the time the cells rehydrate, and start reproducing - i’m not sure if there would be any O2 left for them.
WIth dry yeast, I think it’s more important to pitch the recommended amount of yeast - rather than oxygenating wort.
With liquid yeasts, I always oxygenate.
34/70 will produce acetaldehyde. At low levels, it produces a nice light fruity character. However, to much is considered an off flavor. I think you should let it ferment more if you get too much of it.
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I’ve used 34/70 a lot. Its very robust and clean over a wide range of temperatures. I just started pouring last night from a fresh batch of my “house” lager fermented with 34/70. So great. Clean and clear in a week. I fermented at 55F for 7-days and then bumped it to 65F for two more. In the keg for a week and its good to go. Couldn’t be an easier way to make a lager. (Pils, Vienna, Carapils, willamette and sterling)
theres a reason its one ofthe most widely used lager yeast in the world.
34/70 is great, as is the underappreciated S-189. Diamond is also very good.
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Love 189
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I like S-189 a lot!
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I use 34/70 for all my German lagers, from Pilsners to eisbocks. And I now use it for making Scottish ales (I can’t find Scottish ale yeast locally). Ferment at 62-63 degrees and I’m good.
I’ve been homebrewing for 23 years and have always used Fermentis dry yeast for ales, lagers, etc. If you are doing batches of two gallons or less like I do, you only need a half package of yeast.
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I normally rehydrate my fry yeast first. I have to wait a little while chilling wort anyway. Then I add it to the wort in fermenter and oxygenate. Just what I learned when I first brewed. One packet has been enough.
The one time I tried adding it direct without rehydrating it didn’t work out. Reading other posts I may try that again. I may try 2 packets and not oxygenate. Always a challenge for me to change what has worked though.
Dry yeast manufacturers recommend neither rehydration nor aeration.
Dry yeast cells have a reserve of glycogen which is the compound the yeast cells make from oxygen in the wort, so aeration is useless at best. Rehydrating is also useless, follow the manufacturers instructions and you won’t go wrong. The proper pitch rate for the Fermentis strains is 2 packs per 5 gal unless you’re making an imperial.
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What the yeast makes from the oxygen, is sterols and some lipids, and modern dry yeast is supposed to have good stores of that. Sterols are essential to building cell membranes, and without full stores of sterols, the yeast’s ability to make new cells is limited, as it won’t be getting oxygen later on in the fermentation process.
Glycogen is a carbohydrate, and makes up the yeast’s energy reserves together with trehalose, another carbohydrate. I suppose good dry yeast have plenty of that as well. As glycogen’s main function when we pitch yeast is to supply energy for the synthesis of sterols and lipids from the oxygen we “normally” feed it at the start of the fermentation, it probably isn’t essential when we use dry yeast. Trehalose is, though, as that is mobilized in stress situations - and the yeast certainly is undergoing a lot of stress when working for us. Suddenly handling all that sugar is hard on it, for instance.
This information isn’t useful if you’re always pitching new dry yeast, but it is important if you’re reusing yeast. The glycogen stores are built up towards the end of fermentation, but it’s quite rapidly consumed during storage - especially if storage conditions aren’t optimal. And if you pitch yeast that hasn’t got good stores of glycogen, it won’t be able to use the oxygen you feed it, efficiently. So if you’ve been storing the yeast for more than a couple of weeks, it’s a good idea to feed it some 1.02-ish wort a couple of days before using it. That will allow it to replenish the glycogen stores. (But you’ll also have to take into account that the number of living cells will have been significantly reduced, and the replenishing cure won’t fix that.)
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Many brewers have emphasized the simplicity and reliability of using dry yeast for lagers. Consistency in sanitation and patience during fermentation is key. If you encounter any off-flavors, evaluate fermentation temperature and yeast health as potential factors
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