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Yeast pitching temp for lager

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I'm a new homebrewer and I'm about to try my first lager. I am planning on using SafLager W-34/70, but the Fermentis instructions are confusing (I'm being polite).

Ideal pitching and fermentation temp (according to Fermentis) is 12-15C. However, their rehydration instructions say...

> Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 21 to 25 °C (70°F to 77°F).
> Leave to rest 15 to 30 minute
> Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel
> Alternatively, pitch the yeast directly...providing the temperature of the wort is above 20°C (68°F).

Hmmm...so ideal fermentation temp is 12-15C, but you should rehydrate and pitch above 20C? 🤔

Seems to me there are three options:

1. Rehydrate at 21-25C, then drop temp of yeast (overnight?) and pitch to pre-chilled (12-15C) wort
2. Rehydrate at 21-25C, pitch to wort at 21-25C, then lower everything to 12-15C
3. Rehydrate at 12-15C, pitch to wort at 12-15C

Any advice?

Cheers
 

Hangover68

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I'm fairly green myself to AG brewing and my first lager using 34/70 didn't go so well as i underpitched in error, currently have a pils brewing and this time i used S189 which is humming along nicely. You will need 2 packs of yeast unless you are confident that you can make a starter from 1 pack.
 

bird

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Hey Paul. I make a starter from some wort and put the yeast in about 15minutes before I pitch. Temps generally around 25 when I add the yeast. I then add the starter to my fermenter with the wort still at about 25 and let the fridge cool everything down. I haven't had any problems with this so far. Done 4 lagers like this andthey have all come out nice and clean. I do pressure ferment so I'm not sure if that makes any difference.
 

MHB

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34/70 is probably the most widely used Lager yeast in the world. Available as WPL-830 and W2124 so if you look for information on how to brew with either of these you should find plenty of information.

Yeast hates sudden temperature changes, Lager yeast perhaps even more than Ale. Whatever you do don't go from warm (>18oC) to cool too quickly. That said it is better to rehydrate warmer (21-25oC), you will get more live yeast and it will be in better condition.

Probably best practice would be to rehydrate as per instructions then slowly add wort (say 10% of the volume of the yeast/water) at your brewing temperature, add some every 15-30 minutes until you get down near your fermentation temperature (process called attemperation). When the temperature of both the yeast starter and the wort are close to the same (not more than 5oC different) add the yeast to freshly aerated wort.

If you want really clean (low ester) lager you will need really big pitches, note in the instructions you linked 200-300g/Hl at say 250g/100L (mid point of range/HL) that's 57g in 23L or 5 11.5g packets. That's what it takes to make really good commercial grade lager. Read a piece by the head brewer at Budvar, he said they were pitching 5L of heavy yeast cream/HL, at 8oC. They were getting fermentation over in 3 days at 8oC. Mind you that's about 64 smack-packs of fresh Wyeast in 23L. Not many home brewers are ever going to get anywhere close to that sort of pitching rates, fair to say its pretty hard to over pitch a Lager and very easy to under pitch one.

Step by step
I would put the wort (in a closed cube) in the fridge (turned off) at ambient. Rehydrate the yeast as per instructions. put the yeast in the fridge with the wort.
When both are at ambient temperature (either wait or attemperate as above), add about 500-1000ml of aerated wort to the rehydrated yeast, cover the starter (i use a 2L jug and glad wrap), put the jug in the fridge. Turn the fridge on and set to brewing temperature. The large thermal mass of the wort will stop the fridge cooling too quickly. leave overnight.
Come next day the starter should be working. Transfer the wort from the cube to a fermenter, aerate with O2, add working starter to wort, close fermenter and away it all goes...

As a procedure it works pretty well for me, I would be starting with more than 1 packet of 34/70 (probably 2-3) or more likely a smack-pack of Wyeast (around 2 of dry yeast).

Making good lager is technically very demanding, there isn't much room for taking shortcuts or speeding the process up (other than having masses of yeast available). One of my bucket-list items is to brew a perfect Pilsner, done dam good, but not perfect - yet!
Good brewing Mark
 
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Step by step
I would put the wort (in a closed cube) in the fridge (turned off) at ambient. Rehydrate the yeast as per instructions. put the yeast in the fridge with the wort.
When both are at ambient temperature (either wait or attemperate as above), add about 500-1000ml of aerated wort to the rehydrated yeast, cover the starter (i use a 2L jug and glad wrap), put the jug in the fridge. Turn the fridge on and set to brewing temperature. The large thermal mass of the wort will stop the fridge cooling too quickly. leave overnight.
Come next day the starter should be working. Transfer the wort from the cube to a fermenter, aerate with O2, add working starter to wort, close fermenter and away it all goes...
Thanks heaps for the detailed instructions, Mark. I'll definitely invest in more yeast (I only bought one pack).

What's the purpose of the cube? I use a Fermentasaurus with pressure kit. I can push the air out with CO2 whilst everything cools down. Would that be the same?

Would you advise stepping the temp of the fridge down over a day or two, or too risky from a sanitisation point of view?

Lastly, if the yeast and wort are always at the same temp, why bother with the starter? Why not just pitch and bring the temp down together? Then the yeast would be more protected by the “large thermal mass” of the wort?

Thanks again.
 

MHB

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Good to use more yeast.

Doesn't matter if you use a cube (but I suspect most people are no-chilling in cubes) provided you can guarantee sterility. That's the main reason for about half of what we do in brewing, starting with cleaning and going all the way to packaging.

You could pitch the yeast as bird says into the wort (most yeast research says that re-hydrating in tap water at the recommended temperature gives better results). You just need the wort at the right temperature (i.e. 21-25oC for 34/70) have the wort open to air and maintain hygiene. It can all get a bit hard to manage. Evidence suggests you get more of more viable yeast rehydrating in water.

Other point is that yeast in a well aerated wort will start reproducing rapidly at a temperature in the low 20'soC, this is when yeast produces most of the esters that we want to avoid in Lager brewing.
Its best practice to introduce a working starter at fermentation temperatures, remember that German brewers call 12oC "Warm Fermentation" and regard it as too hot for making premium Lagers. The best Lagers/Pilsners are all brewed in the 8-10oC range (with masses of yeast). If they are brewing at 12oC normally the yeast would be introduced at around 8oC then the temperature allowed to rise to 12oC in an attempt to minimise esters.

Mark
 

bird

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Thanks, bird. So you rehydrate with wort (not water) and that’s not a problem?
I do rehydrate with wort. Its how I was shown. I've only been doing all grain for 7 months now so I'm no expert. But will consider trying with water next time after reading what mark has said. Tap water around here is low 20s at the moment so will make life easier. mark when rehydrating with water is filtered water good enough or does it need to be boiled and chilled to sterilize?
 

Vini2ton

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And now for something completely different. 2 sachets of 34/70 sprinkled into 23lts wort within the prescribed temperature range. It seems to work just fine and dandy. I do it at 15deg and then take it down to 12deg.
 

philrob

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I agree with MHB. When I brew my once a year Pils, I use a Wyeast smakpak and grow it up in a 2½ litre starter. I then repeat the process with about a quarter of the result, and combine all that yeast for a 23 litre batch. I reckon I have the equivalent of about 4 or 5 smakpaks for a 25 litre batch, and it's aerated with pure oxygen. I ferment at 9ºC. The beauty of pitching lots of yeast and fermenting cool is that I really don't feel the need to do a diacetyl rest, because I've never noticed it in my brews.
 

MHB

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In a perfect world as you say boiled and cooled water would perhaps be the best. But just tap water works well enough, tap water has some advantages over distilled or purified water, then again it has some Chlorine that wont help.
Most important is the temperature, being too far outside the range recommended for a specific yeast can kill half of the yeast. The makers test the recommended temperature ranges pretty rigorously so its best to stick to them. Its a really good idea to measure the temperature with a thermometer rather than guess.

You can pitch directly into the wort, but it still pays to follow the instructions. Pitch in the temperature range and at the rates recommended.
Be aware that you will get more esters the less yeast and warmer, less for more yeast and cooler. Most esters are produced during the reproductive phase. Cleanest beer comes from more yeast pitched cool.

Philrob - Yep! a DA rest is a remedial process for beer that was underpitched or otherwise mismanaged, if you are doing everything right you shouldn't need to do one.
Mark
 
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Thanks everyone for your input. In the interests of getting the thing started, I will follow my "experimental" process and see how that turns out and improve from there.

Thanks again 👍
 

hezzer

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I'm new to having the ability to pressure ferment. It seems to be accepted that pressure will suppress ester formation in the same way as lowering the temperature. Now does anyone have figures to equate pressure v temp? e.g does 10psi at say 15 degs give you the same effect as zero pressure and 10 degs? With Fermentis 34/70 going in from a 2 packet/2.5L/two day/12deg starter, should pressure be applied straight away or after say 24 hrs as fermentation starts producing its own CO2?
Thanks for any input. H
 

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