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Thread: Yeast efficiency

  1. #1
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    Yeast efficiency

    Fellows

    One of the recuring issue experienced is slow yeast efficency. We are using US-05 & S-04 from Fermentis and we respectively have between 65 & 70% attenuation with US-05 & 60 to 65% with S-04. We have tried fermenting with and without oxygenating the wort as it leaves the HX toward the FV. We are trying to mash at 148*F on most brew with a mash out at 170F for ~10 minutes. We vorlauf for 10 to 15 minutes before transfering to kwt and boil for ~60 min

    Fermentation temp is usually stable at 68F

    Beers are as low as 12P OG and as high as 16.5 P OG

    We usually use 1 pack of yeast for ~10 BBL.

    I am kind of at a loss as to how to increase efficency ?

    Would you have a couple of pointers to help / guide me ?

    Thanks

    Matt



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  2. #2
    Join Date
    Feb 2014
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    west coast
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    Few quick thoughts, not necessarily to be done together

    Rehydrate yeast with recommended nutrients
    Use two bricks of yeast
    When beer is 50% attenuated let the temp rise a few degrees
    Add nutrients at the 50% attenuation mark
    Blow co2 up the cone to rouse yeast
    Pitch more yeast, say 2/3 initially then 1/3 towards the end


    I think maybe this might be some sort of problem with your wort. Dried yeast typically doesn’t have such wide variations in performance in my experience. At that low temp you should be pretty dry and fermentable.

    Possibly your mash temp readings are wrong?
    Possibly incomplete mash conversion?

    Just some guesses here. Good luck

  3. #3
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    Apr 2015
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    I've almost never had a problem with dry yeast not finishing. The only problem I ever had was when our jackets fluctuated too much due to sticking solenoids, causing sharp drops in temp that flocked a lot of the yeast. I had to rouse the yeast pretty firmly, and even then, I lost some attenuation. I don't know how often you check the actual fermentor temp, or if you've verified that your temp probes are accurate.

    I never rehydrated or oxygenated, having been told by the supplier that neither was required due to the freeze-drying process and the amount of cells in each pack. It does sound like you might be underpitching a bit; for 10 bbls of 12P wort, I would use about 600g of yeast. That means breaking into another pack, but another thing I found out about dry yeast is that, properly handled and resealed, partial dry yeast packs last a few weeks with no discernible loss in fermentation quality.

    Finally, just to give the yeast a boost, when groundwater temp allowed (no two-stage HX, sigh), I would chill to a few degrees below my fermentation temp and let the yeast free-rise up to temp. This usually not only ensured proper attenuation, it would often shave at least a day off my fermentation time. I also performed diacetyl rests on most of my beers, which helped push the yeast to full attenuation. Good luck!

  4. #4
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    Flagstaff, AZ
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    I would start with a forced wort test. Then you will be able to determine if it is your mashing or yeast performance.

  5. #5
    Join Date
    Sep 2005
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    Louisville, KY
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    Agree with Pinto. Start eliminating variables. How long is your mash at 148, is your strike water temp killing enzymes as you mash in? Try more mash time yet? I would also add aeration and or oxygen to the wort post HX.
    Joel Halbleib
    Partner / Zymurgist
    Hive and Barrel Meadery
    6302 Old La Grange Rd
    Crestwood, KY
    www.hiveandbarrel.com

  6. #6
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    Definitely do a forced wort test to determine your expected attenuation. I would also look at the fermentation kinetics. Was the lag phase reasonably short? Long lag phase indicates low yeast viability or underpitching. If the beer has long lingering finish to reach final gravity this might indicate a problem with the fermentation environment (poor wort nutrition, temperature fluctuations, etc).
    Lallemand is a global leader in the development, production and marketing of yeast, bacteria and specialty ingredients.

  7. #7
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    Apart from the forced fermentation to determine the attenuation limit, a couple of other thoughts

    I assume you are using 500 gramme packets. If so, I have found at a couple of breweries that you can use this at at half the going rate and still get full attenuation. So, I would suggest a couple of things

    Are you hydrating the yeast properly - warm sterile water or very dilute wort?

    You shouldn't need any additional wort oxygenation if you are using fresh dried yeast every time - only if re-pitching from a previous brew.

    Are all you temperature probes / thermometers used for mashing absolutely correct? It doesn't take much error to achieve a high WAL

    What are the malts and adjuncts (if any) you are using? Are you using high quantities of difficult to convert grains - poorly gelatinised maize for example? Or are you using malts that really do require decoction or rising temperature infusion mashes rather than isothermal mashes?

    Are you treating the water with sufficient mineral slats or other treatments to get mash pH suitable for the enzyme reactions?

    Are your temperature controls on the FVs causing temperature fluctuations of more than one degree C, which can adversely affect consistent fermentations (one brewery I worked at had many unlagged vessels - so in winter they had lots of periods of low temperatures and slow ferms, along with poor attenuation, and in summer, lots of periods of high temperatures and fast and more fully attenuated ferms.

    Mash consistency? Too thin and you may be killing off enzymes early leading to high ALs
    dick

  8. #8
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    Dick and Eric have all the key questions and considerations there.

    Although I would contend that thinner mashes do not have any scientific reason they would kill the enzymes (?). There are certainly historical styles of beer mashed with very thin mashes.

    Enzymes are very temperature sensitive in most cases, and a thinner mash can easily lead to a higher mash temperature, but provided you are in the range of acceptance to that particular enzyme (or group) you should have no reason for issue. The pH of the mash can be affected by the hydration ratio, and is of major importance to enzymatic activity, but this can be easily adjusted for. Another important factor is the fact enzymes will be further spaced from the actual compounds they act upon due to the thinner consistency. This may require more time and/or gentle mixing to encourage finished reactions, but does not necessarily mean the enzymes are incapacitated in any way. So basically thin mashes require special considerations, but will not lead to killing enzymes.

  9. #9
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    Thank you everybody for all the answers and pointers.

    I will try to answer everybody since you all took your time to guide. Sorry for not answering sooner, production is keeping me very busy this week ! But - Thanks again for your help!

    @brain medicine:
    - Yest Re-hydrate : I have been holding off on that. I've been reading it doesn't help much but I can give it a shot.
    - More yeast and temp increase are good options too. I will do the calculation on yeast cell count to see what's needed
    - I will order yeast nutrients
    - Blowing co2 in cone - I do that to rouse with limited effect
    - Mash reading can be wrong but the external temp reading match the MLT reading (close enough)
    - Mash convertion is complete. I do a test (80% of the time...)

    @spetrovits
    - FV temp is check daily!
    - We have 2 probs on the FV. They are pretty close in temp. Both have been checked as recently as yesterday (knowing that I would answer today!) and both are spot on!
    - I will try to increase yeast cell count. On a side note; we also have this issue when we do a double batch (in 2 days) and have pitched both yeast pack after day one. The intent is to use the first brew has a yeast starter for final double batch
    - Very interesting comment on the pitching temp! I will try this out.

    @pinto21
    - I have never performed a forced wort test. I have researched it a bit and deep dive more to get a good process. If you have recommended material, feel free to share! I will also research on PB forum to see what I can find

    @BrewinLou
    - The mash at 148 last 60 minutes minimum.
    - Our IPA mash at 153F and we have to bring in water at 170F. With the grain temp and heat absorption we get right around 153. Could the 170F water kill enzymes.
    - We have tried mashing for up to 75 min. Should I try longer? We do perform Iodine tincture test for starch conversion verification
    - Ok for the oxygenation recommendation, I will bring it back in the process.

    @ Lallemand Eric
    - Would you happen to have a recommended process for the forced wort test
    - Lag phase is ~ 24 to 36 hours. When I add 2 yeast pack in a single brew (in anticipation of the double batch); it starts in 12 or less hours.
    - I don't think we have a particularly long lingering finish to reach final gravity

    @dick murton
    - Yes, we are using 500g yeast packets.
    - We are not hydrating yeast. We pitch the yeast directly in the FV. Do you recommend doing it? I am conflicted with this as I see a potential risk of infection...
    - Yes, we are using fresh dry yeast everytime
    - Temp prob and thermometers. This could be the issue. Even if - yes - they are calibrated right, the MLT temp prob is not reading accurately and with lot of delay. The brew house supplier is considering sending us a longer prob and they want us to get thermopaste to fill the well. They wonder if the prob may not be touching the end of the thermowell. I am using and handheld thermometer with a long prob to validate mash temp - especially when we increase temp to 170F
    - Our IPA - which we recently keg - had a 64% yeast efficiency and the grain bill is very simple. 13 x 55 lbs of pale malt + 45 lbs of melanoiden malt + 45 lbs of amber malt. Malt supplier is a relatively "big" one here in France. I don't think they are hard to convert grains.
    - Water treatment : we have an RO system and we use brunwater to get guidance on mineral addition. We have a pH between 5.35 et 5.4
    - FV temp is fairly stable. I don't see swings in temp.
    - We do have thinner mash. We had a few stuck mask and we try to now mash at 1.5qt / lb. Last IPA; we were at 290 gal of water for 805 lb of grain + rice husks

    @UnFermentable
    - Thanks for your comments.
    - You mentioned gentle mixing - In an effort to avoid stuck mash (!!!) we recently stopped mixing the mash. We mix just the first few minutes...

    Thanks again for all the guidance and feedback

    Matt

  10. #10
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    The yeast suppliers recommend hydrating the yeast before adding to the FV. I know not everyone does, and I have just sprinkled yeast on the wort in FV myself without any major issues, but it does seem to get going better if you hydrate beforehand.

    Unless brewing very high gravity beers - say 18 Plato or higher, you shouldn't have to oxygenate the wort - see the Fermentis yeast sheets - so all your beers should be OK, though you might want to increase the pitching rate slightly for the 16.5 P beers.

    Search for the fermentis sheet "Yeast Tips & tricks". I'll send you a copy if you can't find it if you PM me with your email address

    If double batching on successive days - pitch sufficient yeast for both brews into the first brew - you get more consistent fermentations and flavour that way.

    Don't bother adding 170 degree water after you have mashed in. 170 sounds very high for initial mashing in anyway - it won't be doing the enzymes much good

    You should be able to get much better than 64% extract efficiency. I would be looking for 90 % or more. What is your malt grind like? If it is too coarse this will give you low extracts, and possibly affect the AL - though this latter should only be very minor. If you are beating all the air out of the mash by over-stirring, you are likely to get channelling and poor extracts unless you have a decent lauter tun set up with properly design rakes, numbers of rakes and reliable control of speed and height. A normal mash tun without rakes - don't agitate. Just get mashed in evenly and leave until sparging.

    If your lag phase is 24 to 36 hours, this suggests underpitching or wort too cold. 12 hours for an ale, 24 hours absolute tops, and that is in a large brewery using the minimum amount of yeast it can get away with.

    Mash pH is a bit high - try adding more CaSO4 or CaCl2. You could use lactic acid, but with RO water calcium salts should be all you need.

    PM me, and I will send you some guidance from Murphys in Nottingham on salts addition - it dows work and is simpler than Brunwater - no offence to half these guys, but a lot of these water calculators are, I sometimes think, an exercise in spreadsheet calculations rather than observing what works in practice. I used to do something similar, but find the Murphys calculations work pretty well and are simpler to do, concentrating on just a couple of key minerals that affect flavour and pH.

    You have a thin mash, more suitable for lauter tuns and mash filters at 3:1. Try reducing to 2.5 :1 liquor to grist.

    I assume you are covering pre-heating the mash tun and covering the plates with liquor before you start mashing in. The 2.5:1 ratio is once you have pre-heated and covered the plates, and only counts once you start actually adding the grain to the liquor.
    dick

  11. #11
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    Quote Originally Posted by Mattieu View Post
    Thank you everybody for all the answers and pointers.

    @ Lallemand Eric
    - Would you happen to have a recommended process for the forced wort test
    - Lag phase is ~ 24 to 36 hours. When I add 2 yeast pack in a single brew (in anticipation of the double batch); it starts in 12 or less hours.
    - I don't think we have a particularly long lingering finish to reach final gravity
    Seems like your kinetics are fine, doesn't suggest low yeast viability.

    For a forced wort test, in general you want to pitch a small volume of wort with about 10x the normal pitch rate (i.e. 5-10g pitched into 1L of wort). You do not have to be precise here, just make sure you add enough to get a very fast fermentation, a few days faster than your main fermentation. After the fermentation settles down, measure the density and calculate the apparent attenuation. If the attenuation is low but equal to the forced wort test, then this suggests that your wort fermentability is low. If your forced wort attenuation is greater than your main fermentation then you might have other issues with wort nutrition, poor aeration, premature flocculation, etc.
    Lallemand is a global leader in the development, production and marketing of yeast, bacteria and specialty ingredients.

  12. #12
    Join Date
    Nov 2018
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    Amboise, France
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    Quote Originally Posted by Lallemand Eric View Post
    Seems like your kinetics are fine, doesn't suggest low yeast viability.

    For a forced wort test, in general you want to pitch a small volume of wort with about 10x the normal pitch rate (i.e. 5-10g pitched into 1L of wort). You do not have to be precise here, just make sure you add enough to get a very fast fermentation, a few days faster than your main fermentation. After the fermentation settles down, measure the density and calculate the apparent attenuation. If the attenuation is low but equal to the forced wort test, then this suggests that your wort fermentability is low. If your forced wort attenuation is greater than your main fermentation then you might have other issues with wort nutrition, poor aeration, premature flocculation, etc.
    Thanks! Sounds like easy enough! I’ll get on that test right away!
    Thanks again
    Matt


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  13. #13
    Join Date
    Nov 2018
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    Quote Originally Posted by dick murton View Post
    The yeast suppliers recommend hydrating the yeast before adding to the FV. I know not everyone does, and I have just sprinkled yeast on the wort in FV myself without any major issues, but it does seem to get going better if you hydrate beforehand.

    Unless brewing very high gravity beers - say 18 Plato or higher, you shouldn't have to oxygenate the wort - see the Fermentis yeast sheets - so all your beers should be OK, though you might want to increase the pitching rate slightly for the 16.5 P beers.

    Search for the fermentis sheet "Yeast Tips & tricks". I'll send you a copy if you can't find it if you PM me with your email address

    If double batching on successive days - pitch sufficient yeast for both brews into the first brew - you get more consistent fermentations and flavour that way.

    Don't bother adding 170 degree water after you have mashed in. 170 sounds very high for initial mashing in anyway - it won't be doing the enzymes much good

    You should be able to get much better than 64% extract efficiency. I would be looking for 90 % or more. What is your malt grind like? If it is too coarse this will give you low extracts, and possibly affect the AL - though this latter should only be very minor. If you are beating all the air out of the mash by over-stirring, you are likely to get channelling and poor extracts unless you have a decent lauter tun set up with properly design rakes, numbers of rakes and reliable control of speed and height. A normal mash tun without rakes - don't agitate. Just get mashed in evenly and leave until sparging.

    If your lag phase is 24 to 36 hours, this suggests underpitching or wort too cold. 12 hours for an ale, 24 hours absolute tops, and that is in a large brewery using the minimum amount of yeast it can get away with.

    Mash pH is a bit high - try adding more CaSO4 or CaCl2. You could use lactic acid, but with RO water calcium salts should be all you need.

    PM me, and I will send you some guidance from Murphys in Nottingham on salts addition - it dows work and is simpler than Brunwater - no offence to half these guys, but a lot of these water calculators are, I sometimes think, an exercise in spreadsheet calculations rather than observing what works in practice. I used to do something similar, but find the Murphys calculations work pretty well and are simpler to do, concentrating on just a couple of key minerals that affect flavour and pH.

    You have a thin mash, more suitable for lauter tuns and mash filters at 3:1. Try reducing to 2.5 :1 liquor to grist.

    I assume you are covering pre-heating the mash tun and covering the plates with liquor before you start mashing in. The 2.5:1 ratio is once you have pre-heated and covered the plates, and only counts once you start actually adding the grain to the liquor.
    Thanks for your answer. I’ll increase yeast cell count on 16P beer! This won’t help.
    170 F is the strike water temper to actually mash at 153.
    As we speak, I am brewing an American amber (batch 2/2) and strike water temp was 165F to mash at 148. We mashed a bit too cold yesterday when strike water was 162. Today we are spot on - on both temperature prob reading)
    We start mash in cold MLT. I might start lower strike temp and preheat the MLT.

    our malt grind is:
    78% > 1mm
    10 % > .5 mm < 1mm
    12 % < .5 mm
    Our rake is on until all the grain is in the MLT - at 20% of it speed. Then it is off until wort is in KTW
    Do you recommend a mash out or sparge after worlauf? I have been mashing out and I am reconsidering this step...

    I am would be thrilled to get different salt addition guidelines - I will PM you!

    Ok for 2.5 : 1 ratio. I just hope I won’t get a stuck mash (happened a lot in the past )

    MLT is not pre-heated. But we do bring the grain once the false bottom has 1 inch of water above it.
    The 3:1 is total water so I might be close to 2.5 ; but I’ll double check on next week brews!

    Thanks again!

    Matt




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