Reusing yeast confidence

[KiterNick]

I have been homebrewing for awhile and recently starting reusing yeasts. It has gone well and I like saving the $$, but with each reuse I become more and more paranoid. The idea of losing a batch of beer....

I'm thinking about abandoning my yeast reuse, looking for things I could check to increase my confidence or know when to stop reuse. I don't want to keep reusing until I get a bad batch of beer. I make starters, but not sure how to tell if the yeast has mutated or if it is wild yeast...

I was a lot less stressed when each batch was new yeast...

 

[05m50dan]

If you're going to reuse yeast, you have to be very careful about sanitation. With clean techniques, you can reuse for multiple batches. Look into threads on washing yeast or yeast slanting, also on YouTube. If you have good technique, and are brewing the same styles of beer, you should be able to get four or more generations out of one liquid yeast pack. I don't take dry yeast past 2 generations.

 

[theck]

I started reusing my yeast as well this year, knock on wood, I just pitched my 3rd gen in an apple cider and waiting (starter looked really good). I just make sure to sanitize everything... I spray everything, hands, inside/outside of jars, lids, etc...

 

[05m50dan]

Another huge point is to not reuse yeast from a high alcohol beer...the yeast get stressed and often mutate...they don't have a good healthy fermentation in the following batch...if you are planning on making a big beer, make a couple standard strength brews, then the big beer to end the cycle with that yeast. And the only time I recommend pitching the whole cake is if you're going really big...Russian Imp Stout, Double IPA, Wee Heavy...

 

[KiterNick]

I get the sanitation and all, just not sure how many generations. I just used WLP001 for 3 generations and WLP005 for 3 as well. I don't think I'm going to try for a 4th, each time I'm more worried...

My fear is less about infection than mutated/wild yeast, how can I tell?

I figure I can tell infection from the starter, as long as it doesn't smell bad and is yeasty, no worries. I read on white labs website that if you should try to get a good sample of yeast in suspension and also that has settled. I'm still not sure how much of the settled yeast I should get...

 

[sikkingj]

I get the sanitation and all, just not sure how many generations. I just used WLP001 for 3 generations and WLP005 for 3 as well. I don't think I'm going to try for a 4th, each time I'm more worried... My fear is less about infection than mutated/wild yeast, how can I tell? I figure I can tell infection from the starter, as long as it doesn't smell bad and is yeasty, no worries. I read on white labs website that if you should try to get a good sample of yeast in suspension and also that has settled. I'm still not sure how much of the settled yeast I should get...

Why not reuse the yeast from a larger then required starter - that way you cut down on the generations as it doesn't age a generation from the starter.

 

[eastoak]

I have been homebrewing for awhile and recently starting reusing yeasts. It has gone well and I like saving the $$, but with each reuse I become more and more paranoid. The idea of losing a batch of beer....

I'm thinking about abandoning my yeast reuse, looking for things I could check to increase my confidence or know when to stop reuse. I don't want to keep reusing until I get a bad batch of beer. I make starters, but not sure how to tell if the yeast has mutated or if it is wild yeast...

I was a lot less stressed when each batch was new yeast...

don't reuse the yeast if it's stressful. but if you really want to reuse the yeast don't wash it since it adds more steps and chance for contamination (and more stress for you worrying about this happening). as soon as you rack the beer off of the yeast scoop the yeast cake into the sanitized jars. if the beer is not infected then chances are the yeast cake is good too. if you wash the yeast the worry wort in you will be asking; "i wonder if that water is really contaminant free, i wonder if something floated into the mix while i was washing....? all night long.

 

[KiterNick]

Maybe what I'm looking for is how do you know when to stop reusing yeast, it sounds like by generation count? I don't want to keep reusing it until I get a bad beer batch...

The starter suggestion was a good one.

Anyone has a story where re-use didn't work out, or maybe as long as the starter works it will always be fine?

 

[LovesIPA]

I found this article very useful when I was exploring re-using yeast: http://www.wyeastlab.com/com-yeast-harvest.cfm

Of note is the part that says you shouldn't harvest yeast from a beer with an ABV higher than 6.5% or a "highly hopped" beer. I thought I remembered reading an upper IBU limit but I can't find it now.

 

[EarlyAmateurZymurgist]

Dumpers are inevitable. Sooner or latter, you are going to have a dumper despite doing everything right. Using good sanitation while cropping, storing, and repitching your yeast cultures will go a long way towards maintaining the health of your pitching yeast. As eastoak mentioned, don't rinse your yeast with boiled water. That's amateur brewer voodoo that is not supported by science. All it does is invite infection because boiled water isn't sterile, the pH of water is much higher than that of beer, and the ethanol in beer is part of a yeast culture's force field. Lastly, I urge you to adhere to the DMWI (Don't Mess With It) and KISS (Keep It Simple, Stupid) principles when you start to think about toying with your cropped yeast cultures. It is easier to propagate a less viable culture than it is to clean up an infected culture.

 

[Cider123]

Well, I'm on my 6th generation with my Wyeast 1469 strain and still going strong. If the yeast mutated it mutated into something tasty.

Mmmm, mutationy goodness


You could always get a smack pack and make a starter, then make several jars from that one starter. You could then have multiple jars of one generation to use. You know...if your paranoid. Oh, but any one of them could have a contamination....scary

 

[theck]

Dumpers are inevitable. Sooner or latter, you are going to have a dumper despite doing everything right. Using good sanitation while cropping, storing, and repitching your yeast cultures will go a long way towards maintaining the health of your pitching yeast. As eastoak mentioned, don't rinse your yeast with boiled water. That's amateur brewer voodoo that is not supported by science. All it does is invite infection because boiled water isn't sterile, the pH of water is much higher than that of beer, and the ethanol in beer is part of a yeast culture's force field. Lastly, I urge you to adhere to the DMWI (Don't Mess With It) and KISS (Keep It Simple, Stupid) principles when you start to think about toying with your cropped yeast cultures. It is easier to propagate a less viable culture than it is to clean up an infected culture.

What should you rinse with then?

 

[EarlyAmateurZymurgist]

What should you rinse with then?

One does not need to rinse yeast with anything. Professional brewers do not rinse cropped yeast. Keeping the yeast culture with the break material can be beneficial to the health of the crop because it is a source of lipids and zinc.

The low pH and ethanol content of the beer fraction of a crop help to keep wild microflora at bay. Replacing the green beer with boiled tap water raises the culture's pH and removes the ethanol (ethanol is toxic to most microflora). Boiled water is not sterile. It's more like super sanitary in that moist 212F/100C heat does not kill spores, which are free to germinate and feed on dead yeast cells because one discarded the culture's force field.

With that said, if one absolutely has to separate the yeast from the break in a crop, the best time to do it is shortly before pitching the crop. If a bottom-crop is more than a week old, one should decant the liquid fraction (a.k.a. the supernatant) and replace it with fresh bitter wort twelve to twenty-four hours in advance. This practice will "proof" and revive the culture. It will also result in a substantial percentage of the viable yeast cells being in suspension when it comes time to pitch. If one is repitching a bottom-cropped culture that is less than a week old, one can decant the clear liquid fraction and replace it with fresh wort from the batch before swirling the solids into suspension, waiting a few minutes for the heaviest fraction to settle, and pitching the liquid fraction into one’s batch of wort.

Finally, a little known fact in the home brewing community is that high levels of trub in a fermentation leads to lower ester concentrations in the finished beer because trub has a stimulatory effect on yeast growth. Trub provides yeast with nucleation sites that help it remove carbon dioxide gas; therefore, improving growth [*].


[*] Brewing Yeast and Fermentation, Christopher Boulton and David Quinn

 

[boydster]

EAZ, great info! Thanks for sharing and including the reference. I just picked up a copy of that book, can't wait to dig into it.

 

[AerationStation]

Just to play devils advocate here, I've heard that while trub does have beneficial effects on the yeast, the amount of trub needed to see these benefits are minimal.

Along with that, i would think the dead yeast cells in the trub would begin to autolyse if the healthy yeast and trub are stored together. There are also probably other compounds as well (I.e hop resins) that may inhibit vitality.

I agree that boiled water is not sterile, however I do think there would be some benefit to rinsing that slurry with either sterile water (from a pressure cooker or autoclave) or beer to remove some portion of the trub. Even after rinsing there should still be plenty of micronutrients available.

As far as long term storage of slurry goes I do agree with the point about storing under an acidic medium to prevent any nasties from taking over. The caveat to that being that I don't feel any one should be saving slurry for too long anyway

Finally, I believe that big brewers are able to transfer the full slurry (if they so choose) because they are doing completely closed transfers and have very active yeast. This means the amount of dead and dying yeast would be less and any contamination would be minimal.

Just my $.02

 

[theck]

One does not need to rinse yeast with anything. Professional brewers do not rinse cropped yeast. Keeping the yeast culture with the break material can be beneficial to the health of the crop because it is a source of lipids and zinc.

The low pH and ethanol content of the beer fraction of a crop help to keep wild microflora at bay. Replacing the green beer with boiled tap water raises the culture's pH and removes the ethanol (ethanol is toxic to most microflora). Boiled water is not sterile. It's more like super sanitary in that moist 212F/100C heat does not kill spores, which are free to germinate and feed on dead yeast cells because one discarded the culture's force field.

Got ya... I'm pretty new to reusing yeast (used to have a more disposable income before kids) and can't afford all the extra equipment needed to really do the job well. I have washed it with the boiled water method a couple times already and I'm pretty anal about sanitation so far I haven't had any issues. What would you recommend be a better way to save and reuse yeast? Rack beer to bottles/kegs, swirl cake and rest of what's left on bottom, drain into sanitized jars and pop into the fridge? To be honest if that's the case I'm all for it... I found the boiled water method a little too time consuming and messy sometimes, plus I am going though mason jar lids fast too since on cool down the jars would seal.

 

[PRE66_6TART]

What would you recommend be a better way to save and reuse yeast? Rack beer to bottles/kegs, swirl cake and rest of what's left on bottom, drain into sanitized jars and pop into the fridge? To be honest if that's the case I'm all for it...

That's exactly what I do.

 

[KiterNick]

I have been reading a lot and I tend to agree that washing is unneeded and that the beer you made is the best storage medium. I have been playing around with my methods, but I think what I may latch onto is intentionally leave a little bit more beer than I usually do (I usually tip it and pretty much get every drop). I will leave enough to get a good swirl. Then, I think I will capture the full cake in a 1 quart jar and shake it up good and let it settle for about 15 min. Then pour into 1 pint jars until I hit the really thick trub. I will put those in the fridge and make starters. If starter seems good I will keep going to maybe 5 generations until I have no problems and higher confidence, then maybe I'll try 10...

Below is what my resuse has been, it has been a little different each time as in some cases it was a last minute decision....

1st was a brew right after a brew, I racked while the wort was boiliing. I had almost no liquid on top of the cake after racking, then I poured the little liquid off and caught the 1st cup (8 oz) of thicker material. in a washed glass cup that I used stars san on I put aluminum foil (stars san) over that and pitched it about 90 minutes later. I didn't worry about this one that much and saw fermentation quickly...

2nd was from a case where I stored the yeast on a whim, I just rinsed and put stars san on the white labs vial. I again poured the liquid off the cake and then filled it until full with the first thicker material, no swirling or anything. In this case I made a starter and it looked fine, so I pitched it. It was stored in the vial for maybe 2 weeks in the fridge. I did worry about this one a little bit more, but not that much...

3rd and 4th were like the first, slight worries since it was added generations, but coming from the bottom of beer directly into new wort seems less risky...I think I will also do this when the timing works out...

5th was same as the third, but this time I stored it for maybe 2 months. I was worried about it and watched the starter carefully. This time I pour the liquid off into a cup and drank it (usually I pour the liquid off the starter, but I have never tasted it), it was not good or bad, but I definitely wouldn't buy it. It didn't taste like good beer... I read online and it sounded like starter remnants usually don't taste good and if it doesn't make you puke it is ok to use. So, I used it. This one is in secondary now and dry hopped, I'm hoping it is good but a little worried beacuse of how the starter tasted...

The whole washing thing seemed like way to much work, but I could totally santitize the white labs vial and fill it. I really liked that process and it was easy and quick, but it doesn't seem like anyone else does it and I thnk I should catch more yeast when I harvest...so I bought the mason jars...

 

[EarlyAmateurZymurgist]

What would you recommend be a better way to save and reuse yeast? Rack beer to bottles/kegs, swirl cake and rest of what's left on bottom, drain into sanitized jars and pop into the fridge? To be honest if that's the case I'm all for it...

My only caveat is that you should let the heaviest fraction settle after swirling the solids into suspension before decanting the liquid fraction into one sanitized jar. I usually crop between 250 and 300ml from a primary fermentation vessel, which means that I am taking the lightest fraction. Ideally, you want to serially repitch a culture at least once every two to three weeks. Any culture that cannot be repitched within a month should be discarded. Cropped yeast stored in canning jars is not a replacement for a proper yeast bank. Long-term yeast storage is best performed using malt agar slants. Agar slants remain viable for up to two years (however, one should plan to subculture a slant at least once every six months). I kept several cultures alive for ten years on malt agar slants in my old bank. The only reason why they did not last longer is that I lost interest in the hobby.

 

[EarlyAmateurZymurgist]

One more thing: being able culturing one's own yeast allows one to purchase cultures from major culture collections. Few amateur brewers can afford to spend $70.00+ for a yeast culture that is used once. However, several of the cultures in my current bank cost more than $70.00 to acquire. I can afford to spend $70.00+ on a yeast culture because I only purchase it once. After the initial purchase, the culture resides in my bank on slant until I decide that I no longer care to maintain it. Several of the strains in my current bank came from plating commercial beers; therefore, they were basically free because I enjoyed the beer.

 

[theck]

My only caveat is that you should let the heaviest fraction settle after swirling the solids into suspension before decanting the liquid fraction into one sanitized jar. I usually crop between 250 and 300ml from a primary fermentation vessel, which means that I am taking the lightest fraction. Ideally, you want to serially repitch a culture at least once every two to three weeks. Any culture that cannot be repitched within a month should be discarded. Cropped yeast stored in canning jars is not a replacement for a proper yeast bank. Long-term yeast storage is best performed using malt agar slants. Agar slants remain viable for up to two years (however, one should plan to subculture a slant at least once every six months). I kept several cultures alive for ten years on malt agar slants in my old bank. The only reason why they did not last longer is that I lost interest in the hobby.

So, the best method in your opinion would be to swirl, let it rest, decant the top liquid a bit, move the rest into the jars, leave most of the trub and refrigerate? I have been pretty much reusing the yeast in 1-2 weeks in various other brews or ciders so they don't stay too long in the fridge to get nasty.

 

[theck]

Would this be a good resource for yeast culturing?

http://www.realbeer.com/spencer/yeast-culturing.html

 

[05m50dan]

Short answer, no. His information is close, but not quite there. Boiling anything does not STERILIZE it only SANITIZES. There are spores of mold and other microorganisms that will survive boiling temperatures and potentially infect your cultures and then your beer. I believe there is a Forum Sticky on Yeast Banking that I used to learn how to culture. You need a pressure cooker that will get the temps up to 250°F, which will STERILIZE the slants/culture medium so you can make clean cultures.

 

[EarlyAmateurZymurgist]

So, the best method in your opinion would be to swirl, let it rest, decant the top liquid a bit, move the rest into the jars, leave most of the trub and refrigerate? I have been pretty much reusing the yeast in 1-2 weeks in various other brews or ciders so they don't stay too long in the fridge to get nasty.

No, the top liquid is what you want to collect. The rest should be discarded. If you are waiting until supernatant forms, you are waiting too long after swirling to take your crop (supernatant is the clear liquid that sits on top of the heavier materials). The goal is to swirl, wait a couple of minutes (like less than 5), wipe the pouring edge of the fermentation vessel 91% isopropyl or grain alcohol (think about what a nurse or doctor does before giving you an injection), and decant the thinnest fraction. You are still going to carrying some trub over from the fermentation vessel, but your cropped culture should be at least 50% yeast.

Cropping isn't about building up a huge reservoir of yeast to use in the future. Cropping is about collecting yeast for the next batch of beer. Ideally, a brewer should limit cropping activity to his/her house strain(s). Strains that are used infrequently should be kept on agar slants or purchased when needed.

 

[EarlyAmateurZymurgist]

Would this be a good resource for yeast culturing?

http://www.realbeer.com/spencer/yeast-culturing.html

No, that process is flawed. All media should be autoclaved (a.k.a. pressure cooked at 250F/121C). Liquid cultures should be plated for "singles," which are then used to inoculate slants. I documented the process in another thread that took a strange tangent.

See: https://www.homebrewtalk.com/f163/conflicting-advice-lhbs-hbt-447056/index6.html#post5736825

 

[theck]

No, the top liquid is what you want to collect. The rest should be discarded. If you are waiting until supernatant forms, you are waiting to long after swirling to take your crop (supernatant is the clear liquid that sits on top of the heavier materials). The goal is to swirl, wait a couple of minutes (like less than 5), wipe the pouring edge of the fermentation vessel 91% isopropyl or grain alcohol (think about what a nurse or doctor does before giving you an injection), and decant the thinnest fraction. You are still going to carrying some trub over from the fermentation vessel, but your cropped culture should be at least 50% yeast.

Cropping isn't about building up a huge reservoir of yeast to use in the future. Cropping is about collecting yeast for the next batch of beer. Ideally, a brewer should limit cropping activity to his/her house strain(s). Strains that are used infrequently should be kept on agar slants or purchased when needed.

The trub is just dead yeast right, so if you collect that no hard no foul, correct... it will just drop to the bottom of the current batch?

 

[curtw]

I found that my confidence in harvesting a yeast cake after fermentation is much lower than just doubling the yeast I've just bought.

So when I buy a vial of White Labs yeast, I make a 1.5L starter, cool, decant, and pour into two vessels. One I pitch with, and one I save in the fridge.

Then when I want to use the same strain again, I'll make a big starter (maybe with two steps, if it's been in the fridge for a while), decant, split, and repeat.

Seems cleaner to me than dealing with trub, dry hopping, etc.

 

[EarlyAmateurZymurgist]

The trub is just dead yeast right, so if you collect that no hard no foul, correct... it will just drop to the bottom of the current batch?

Trub is mostly coagulated protein. The trub that you carry over will sink to the bottom of your primary fermentation vessel.

If you crop correctly, you should not get more than 100mls of trub in a 300ml crop. That's a less than half of a cup of trub. The amount of trub that you carryover will be dependent on how much fluid is left in your primary fermenation vessel after racking. IF you adopt a 5.25 to 5.5 gallons goes into the primary rule, you should have enough liquid to limit the trub carryover to 50mls or less.

 

[EarlyAmateurZymurgist]

Seems cleaner to me than dealing with trub, dry hopping, etc.

That's why I recommend using a secondary fermentation vessel when dry hopping. The threat of oxidation is somewhat overblown on this forum. The miniscule amount of oxidation that may occur during racking is going to more than offset by the hops.

 

[theck]

I found that my confidence in harvesting a yeast cake after fermentation is much lower than just doubling the yeast I've just bought.

So when I buy a vial of White Labs yeast, I make a 1.5L starter, cool, decant, and pour into two vessels. One I pitch with, and one I save in the fridge.

Then when I want to use the same strain again, I'll make a big starter (maybe with two steps, if it's been in the fridge for a while), decant, split, and repeat.

Seems cleaner to me than dealing with trub, dry hopping, etc.

Great idea I'll be doing that next time. How long have you let the spare sit before using? How long after pitching do you separate?

 

[negativereaction]

I found that my confidence in harvesting a yeast cake after fermentation is much lower than just doubling the yeast I've just bought.

So when I buy a vial of White Labs yeast, I make a 1.5L starter, cool, decant, and pour into two vessels. One I pitch with, and one I save in the fridge.

Then when I want to use the same strain again, I'll make a big starter (maybe with two steps, if it's been in the fridge for a while), decant, split, and repeat.

Seems cleaner to me than dealing with trub, dry hopping, etc.

This method is what I use, and really seems to be the happy medium between trying to wash the junk that comes out of your primary, and doing real frozen yeast banks with pressure cooker sterilization, and all that that entails.

I've yet to have any trouble reviving my yeast starter 'forks', even after a 6 mo stint in the fridge. I use tiny mason jars, and it's always nice clean yeast that I start with. It's almost like you're simply starting with a small vial of brand new yeast.

Prior to that, I always had mason jars in the fridge full of 'washed' yeast, full of various levels of junk and I was always unsure how much was yeast and how much was trub, hop particles, etc.

 

[theck]

This method is what I use, and really seems to be the happy medium between trying to wash the junk that comes out of your primary, and doing real frozen yeast banks with pressure cooker sterilization, and all that that entails.

I've yet to have any trouble reviving my yeast starter 'forks', even after a 6 mo stint in the fridge. I use tiny mason jars, and it's always nice clean yeast that I start with. It's almost like you're simply starting with a small vial of brand new yeast.

Prior to that, I always had mason jars in the fridge full of 'washed' yeast, full of various levels of junk and I was always unsure how much was yeast and how much was trub, hop particles, etc.

You guys letting the starter sit for a good 24 hours too?

 

[negativereaction]

You guys letting the starter sit for a good 24 hours too?

How do you mean? I have my starter on a stir plate for at least 2-3 days, crash for probably 24 hours, decant the liquid, then throw it back on the stirplate at the start of brew day to get it warmed up and mixed up again. I'll then steal a portion for my mason jar for future usage just prior to pitching the rest into my wort.

 

[theck]

How do you mean? I have my starter on a stir plate for at least 2-3 days, crash for probably 24 hours, decant the liquid, then throw it back on the stirplate at the start of brew day to get it warmed up and mixed up again. I'll then steal a portion for my mason jar for future usage just prior to pitching the rest into my wort.

Got ya. I do a starter 24 about hours before I pitch. I don't have a stir plate.

 

[negativereaction]

Ah. It's best to try and get the starter going a couple days prior to pitching. 24 hours isn't really enough to get the maximum value out of whatever wort you have in your starter vessel; you'll at least know if the yeast is alive, but they won't have had the full window of time to reproduce. A couple days at least is better.

 

[curtw]

I finally broke down and bought a stir plate (Hanna). It's pretty awesome, and, according to all the calculators, I should be ending up with at least 50-75% more yeast cells then I did by occasional swirling.

 

[05m50dan]

FYI, splitting a starter, though not a bad idea, may not leave you with the right amount of yeast for your fermentation. You should always check a yeast pitch rate calculator to make sure you are pitching the right amount of yeast.

For example, a 1.050 OG 5.25gallon batch of wort should get a full 1 Liter starter on a stir plate according to mrmalty.com. If your OG is higher, you'll need more. By splitting a 1.5 Liter batch in half, your underpitching by about 25%. Plan ahead and make a bigger starter, or only decant into your mason jars the amount above what you need for the batch you are making. I would also portion out the amount while the starter is fully stirred up...once you cold crash it, you'll not be as able to portion off accurate volumes of yeast...i.e., make a 1.5 Liter starter with stir plate. When ready to pitch, pull off stir plate, use magnet to hold stir bar, and then decant 1 liter into your wort, saving in the flask (or whatever vessel you are using) the other 0.5 Liter. Then you can cold crash, decant, and save just the slurry. The 1 Liter of starter will not affect your beer significantly, especially since you'll have that much in trub after your done fermenting.