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Correctly Rehydrating Dry Yeast

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Advantages of Using Dry Yeast



Dry yeast has a lot of advantages over liquid yeast. It is cheap and readily available. If stored cool and dry, after 2 years the cells still have a viability over 90%. The form factor is small and one packet contains around 230 Billion cells. That is more than enough for a 5 gallon batch. The biggest drawback is limited variety. Not all yeast strains are available in dried form. I am still waiting for a hefeweizen dry yeast with the same qualities like their liquid counterparts. In conclusion, if you are brewing ales or lagers where good quality dried strains are available, dry yeast clearly has the edge; therefore, I would recommend to always keep a few packets in the fridge.

Why Rehydrate Dry Yeast?


It is possible and it certainly works to sprinkle the yeast directly onto the wort, but there are negative side effects. A lot of cells are going to die in the process. Some of them start unhealthy and many are stressed. There is a risk of mutants and a lot of dead cells are going to end up in the wort. In addition, to get to the correct cell count you have to use about double the amount of dry yeast. This is money that could be invested for better things, like more malt and hops. Correctly rehydrating dry yeast is important. Yes, this adds a few steps to your brew day, but remember that it is the yeast and not the brewer who makes the beer.

How to Correctly Rehydrate Dry Yeast



Here is how to rehydrate one packet or 11.5g of dry yeast. You can scale the numbers accordingly to your quantities.

Things you need:


Microwaveable container (best with lid): This could be a drinking glass, mason jar, or Pyrex measuring glass. Microwave safe plastic should also work well. For one packet of yeast you need around 2 cup (~475 ml) of volume.
Microwave: Any microwave is ok, it just needs to be big enough for your container.
Thermometer: You can take your default brewing thermometer. A quick measurement and long probe are beneficial.
Yeast rehydration nutrient: Go Ferm Protect is the standard - you will need 1.25 grams per gram of dry yeast (13.75g for the 11.5g yeast packet).
Water: Bottled spring water is best; however, whatever water you normally use for brewing should probably suffice (the small amount of chlorine found in tap water has not been shown to have a negative impact here. You will need 20X the weight of Go Ferm as your water in ml (275 ml or just under 1 ¼ cup for you 11.5g yeast packet).

Timing


Start about 2 hours before pitching. This is about the time it takes to naturally cool 1 cup (236ml) of boiling water to 95F (35C). The timing could be different for you, make a trial run before your brew day. Starting earlier is better than later, you can always reheat the water if it gets too cold. At the same time you should also take the yeast packet out of the refrigerator.

Measuring


Take 20x times the amount of water as the amount of Go Ferm you will be using when you rehydrate your yeast. For a normal 11.5g packet, you would use 13.75g of Go Ferm, so this would require 275ml of water (just under 1 ¼ cup). If your water source is good, use normal tap water if not you can use bottled spring water. Demineralized or distilled Water is not ideal. Put that water into your microwaveable container. About half of the container should still be empty, that way it is easier to mix later.

Boiling


Warning: If your container has a lid, leave it open for the steam to escape and never put metal into the microwave. Place the half filled container into the microwave. Nuke it until the water boils. Turn off the microwave and leave your container in there to slowly cool down.

Temperature Check


30 - 60min before you want to pitch the yeast take the container out of the microwave. Swirl the water around to even the temperature. Sanitize your thermometer probe, and then check the temperature. The water temperature must be between 95F (35C) and 105F (40C). This is very important. Dry yeast likes to be rehydrated very warm. If the water is already too cold, you can heat it up again by nuking it for a few seconds in the microwave. Don't forget to swirl before you take a new measurement.

Soaking


Once the water has cooled to the proper temp add the Go Ferm, and then swirl with something sanitized (I use the sanitized probe of my thermometer) until completely dissolved. Next open the packet and sprinkle all the yeast on top of the water. Don't stir it yet. Just close your container or put it back into the microwave (without turning it on). If you don't have a lid, you can cover it with some aluminum foil.
If you have a sealable container, you can put it into the refrigerator while rehydrating. I do this when preparing yeast for a lager. The temperature will go down quicker and the cells will be better acclimatized when it's time for pitching.

Mixing and Pitching



After 15min - 20min, the yeast should be soaked. Now you can swirl it around or mix it, again, with something sanitized. The yeast is now ready to pitch. There is a tradeoff between the time you wait and the temperature of the prepared yeast. It should be as close to the wort temperature as possible to avoid temperature shock. Don't leave the yeast sitting around for more than 1 hour. The cells will start to use up their glycogen reserves. If your wort is no more than 10F (7C) colder than your yeast, it should be good to pitch.

Final words


So this is how you correctly rehydrate dry yeast. Remember to always use proper sanitization techniques when working with yeast and wort at low temperatures. Take care when handling hot liquids. I hope you will save a lot of money and yeast cells by adopting this technique. Thank you for reading and feel free to add any comments below.
 
Lukas Holenweg
Great article!
I usually do not use any nutrient to rehydrate my dry yeast, but I'm sure it does not hurt to!
Any idea if regular yeast nutrient like Yeastex is suitable? I usually use these nutrients in my last 15min boil.
 
I have never rehydrated my dry yeast. I just pitch it dry right on the aerated wort and I've never had any problems with off flavors. And I've never used more than one pack at a time. I predominantly use liquid yeast (Wyeast) for the most part though but I do use US 05 anytime I'm making IPA's or pale ales.
 
Just like anything else in brewing, there is more than one way to do things. Some ways may work but may not be the best option. Many people sprinkle dry yeast into their wort and make good beers. Though it has been well documented that some yeast die off when sprinkled right into wort because the cell walls don't block out the sugars.
 
Thanks for the info!
How about building a starter with dry yeast, ( stir plate and all)?
Any advantages there?
Same basic method as with liquid yeasts, or have you tried it?
 
No you don't want a starter for dry yeast for the same reason it is better to rehydrate and not sprinkle right into the wort. A starter is just a small beer. Sugar is bad for the cells until the cell walls can keep it out.
 
if you read on the back of danstar yeast it gives you directions on how to pitch there yeast..also some yeasts have lag times in how long before they start showing krausen
 
Very interesting, I've never come across an article recommending GoFerm for rehydrating dry beer yeast. I've seen it recommended for wine yeast when making mead. Anyone else use this for beer?
 
Thank you jojacques. I'm the author of this article and normally do not use nutrient. The information about GoFerm was added by the editor. You could compare the ingredients of both, but either way your yeast will be fine.
 
Hello guitarguy6, beer wort already contains all the nutrients the yeast needs, this is why it is usually not necessary to add anything. I did not try to use any nutrient yet when rehydrating dry yeast. I can't say if it helps or hurts.
 
So you say it is wrong to follow instructions from the manufacturer? Fermentis: REHYDRATION INSTRUCTIONS:
Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 25 to 29°C (77°F to 84°F).
Leave to rest 15 to 30 minutes. Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel
 
Hi, nice tips!
What's the difference between adding nutrients in the boil vs to the rehydrated yeast? I've always used nutrients when I make starters but never when rhydrating dry yeast.
 
This is good, but seems overly complex. Just pour the yeast in into warm water, wait 20-30 min and put it into the cooled wort... The directions on the back of the package of yeast are sufficient.
I don't know why you would boil and cool the water, if you pitch a whole package of yeast it's going to eat all the sugars in the wort long long before any other stray yeast will be able to.
 
Manufacturer's recommendations are not necessarily "wrong" however they are not the BEST method either. Danstar's instructions are the EASIEST way for you to probably get an OK beer. Why not take a few extra steps to ensure you get the most out of it? Ever seen the back of a Whitelabs bottle? I seriously hope you don't think their directions to "ferment WLP001 at 75 degrees" is the BEST way to use their yeast. Use some common sense.
 
You boil the water prior to adding the yeast for sanitization purposes--sanitize both the water as well as the vessel containing the water--a couple minutes of boiling seems like pretty smart insurance to reduce the risk of contamination. Secondarily, if your water has chlorine in it then boiling the water will drive off some of the chlorine.
 
I'm scratching my head over this. I've heard where yeast nutrients are used near the end of the boil, in starters, and now in rehydrating dry yeasts. Are they all equally important, or would nutrients best be used for rehydrating the yeast above all else?
 
Where are you getting your numbers for cell count? 230B is 20B/g whereas Fermentis say there is 6B/g in a packet of US-05.
Cheers
 
Hi Ian, i boil the water to sanitize both the water and the container. For me it does not add more complexity because i would have to heat the water anyway. I just do it early in the brewday and leave it sitting in the microwave. When its time to add the yeast it has the perfect temperature. You are probably right with the microbe count. But i like to take precautions with everything that touches cold wort. Cheers!
 
Try Mangrove Jack's M20 for a dry Hefeweizen yeast. I had excellent results with a step mash and fermenting at 22 Celcius. Does not compare to WB06 at all, it's a proper Hefeweizen yeast.
 
I do something similar, but have not used any nutrient. It doesn't have to take nearly two hours to do either. I nuke about 4oz of tap water in a microwave. I then pour the water in a sanitized stainless steel pint cup so I can use my faucet to cool the water faster (swirl the cup while running the tap water along the bottom). I pour the yeast in that, cover with a sanitized towel, and let it sit for 15-20 minutes. Then I stir with a sanitized spoon and finally pitch my yeast in the wort.
Whole process probably takes 30 minutes tops.
 
Great article! I have just started using Go-Ferm to rehydrate dry yeast. I have noticed my yeast proofing better, and I like to give it all the help I can.
I have a 500ml Erlenmeyer flask for rehydrating. I microwave the water/GoFerm mixture to boiling until the whole flask is hot and sanitary. I have to watch the boiling process carefully as it can erupt easily. Then I cover the mouth with a piece of sanitized foil and set the flask in a bowl of ice water to bring the temp down. Add yeast, let it set for 15 minutes, then swirl the flask to put the yeast in suspension. Then pitch.
 
The old "I've never had a problem" chestnut.
Just because you haven't had an issue, doesn't mean others haven't or won't...
As a minimum, you should always following the recommended practice of rehydration and yeast pitching rates. it always irks me, when people say this, because others take it on board and do it, then complain their beer is crap.
i will saythough, that this is a little OTT for rehydration IMO, however a nicely written article.
 
Hi BC,
Sean Terrill did multiple cell counts (US-05) and found that there are around 22.9 billion/gram. There is also MrMalty that states an average cell density of 20 billion cells per gram. I did not do any cell counting myself but i assume these numbers are correct. Dry yeast manufacturers often state a absolute minimum on their packets.
 
Thanks Yesfan, that seems to be a good cooling technique to use before pitching lager yeast, i will be on the lookout for a stainless cup. It is sometimes a little nerve wrecking to wait for the yeast mixture to cool down to (near) wort temperatures.
 
I used one packet for a 6 gallon batch (sprinkled dry, not rehydrated, because slightly underpitching hefeweizens is OK), and brewed the beer according to the "banana" guidelines indicated in this article : http://braumagazin.de/article/brewing-bavarian-weissbier-all-you-ever-wanted-to-know/
At the end I got a perfect Weissbier, resembling Weihenstephaner Vitus (taste & aroma & mouthfeel).
I think that step mashing makes also contrubutes to the difference on wheat beers, because a microbrewery here brews an "acceptable" wheat beer using WB-06 and proper step mashing. My single infusion WB-06 beers were borderline drinkable (overly tart-sour with no classic Hefeweizen taste)
 
Hey, I'm the editor of the article, and I added in the bit about using Go-Ferm as a re-hydration nutrient. I got it from Mary Izett's wonderful book Speed Brewing. I've been using this technique ever since I read here book, and I've had great success with it. My dry yeast definitely seem to proof better, and I like to do everything I can to help my little yeastie friends on their way.
You can read more about it from here book here - https://books.google.com/books?id=o1IbCgAAQBAJ&pg=PA12&lpg=PA12&dq=speed+brewing+go-ferm&source=bl&ots=aN4dSeyEGy&sig=QFISrH10EHmj0AEnWZM7JNsmLLo&hl=en&sa=X&ved=0ahUKEwiky8XSgPLTAhVNyGMKHWehDD8Q6AEIQzAE#v=onepage&q=speed%20brewing%20go-ferm&f=false
 
I'm impressed. This is usually a religious debate. Everyone is keeping it together on this one. I am so proud of all of you! ;) I personally feel that rehydrating dry yeast is good to do if you can work it into the brew day. If for the only reason is that it "proofs" the yeast and you will almost always have a successful pitch if the yeast "proofs" first. Its is one less thing to worry about at that point.
Having said that, I often forget to get it timed right. Most of those times I'll dry pitch. You do lose about 1/2 the yeast by doing this (or so it is said), but that is: 1. only one reproduction cycle (this process is exponential not linear) and 2. dry yeast has way more actual cells than the manufacturers claim, unlike liquid. So, usually you are just fine doing it either way. Rehydration does have a slightly higher infection risk, so you really want to get the water up to at least 150F or so and then let it coast down to the 70-90F or so for "quick proofing activity". You DO NOT need to boil the water. Look at milk pasteurization charts if you have any questions about this.
As for adding nutrient... hmm.. I thought that you were proofing the dry yeast to help the cell walls re-acclimate to the wet conditions. I have seen it claimed that you do not want to have food--sugar-- for the yeast at the proofing time. I am unsure that it is a good idea. This could be a good experiment. For now I am going to disagree with the editor on this. It is known you don't want too pure of water, like distiller or even RO, to rehydrate, however, so maybe this is the book authors solution to making sure the tap water actually has proper minerals? This could be a good beer experiment.
And for pitching multiple packs: Really big beers and/or big batches (like 10+ gals) really do need it in most cases. Dry lager yeasts. See on that one I'll do a starter (yes even and especially for W34/70). Most people would say "use two packs" but from experience I wouldn't go less than three. And at that point liquid and a starter is cheaper. Yes, In a five gallon batch. So there are definitely times you need more than one pack when using dry (or making a starter).
 
How to rehydrate yeast in 4 simple steps:
1. Make yeast starter with 10:1 water to DME ratio by weight.
2. Cut open dry yeast sachet.
3. Pour contents in trash.
4. Open liquid yeast vial or smack pack and pitch into starter.
Congratulations, your yeast is hydrated.
 
“ferment WLP001 at 75 degrees”
The back of WLP001 says no such thing. It says 65F-69F, which seems perfectly reasonable to me.
 
Boiling water won't drive off chloramine, which is far more common that chlorine.
Best bet is to use bottled spring water, which is chlorine free, and doesn't need boiling either, because it's already as sanitary as it will get by boiling. There's also nothing gained by doing more than sanitizing the vessel, with starsan or similar. The first time the yeast and any bacteria in the vessel will see food is in the wort. That you've just put into a fermenter sanitized by the same method.
 
Great information, I'm sure the mash/grain makes a big difference. I was at the wyeast tasting room and they had a batch fermented with typical hefeweizen yeasts and a neutral yeast (California Common) and to my surprise all of them had hefeweizen characteristics (banana esters). I even asked and the guy responsible just told me "you are right it should not be this way". It could be that they made a mistake but i want to investigate.
 
This could be an interesting factor to investigate. Oxygen is still soluble to about 6mg/l @35 C but after boiling there should be none left. Sadly i don't have a dissolved oxygen meter.
 
Hi drgonzo, thank you for clarifying and editing. I have read up a little bit on goferm protect. It seems to be specifically designed for yeast rehydration in the wine industry where high gravity and very low oxygen levels can lead to problem fermentations. They claim to increase yeast viability and vitality. In their datasheet the yeast with nutrient added produced higher levels of dissolved co2 over time than the control group. Which equals a more active fermentation. I think this could be interesting for very high gravity worts. We should do a side to side experiment on this.
 
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