My Dad and I have been homebrewing for many years now and have noticed a trend that we are looking for insight on how to improve. Generally speaking we are never able to achieve the attenuation desired that is well within range of what the yeast is supposed to achieve. We have tried a number of different adjustments over the years but just generally seem to be stumped on how to get that last bit to drop out. Has anyone else experienced similar issues and if so what recomendations might exist for getting the very bottom to drop out? Thanks.
I think you will get a lot of useful answers if you provide a bit more info: are you all grain or extract brewers? What yeasts are you using? Are you making starters? How are you aerating the wort, and how do you regulate fermentation temperature?
Almost exclusively all grain brewing with a variety of different yeast strains as appropriate for the styles. Most of the time a starter is used and the wort is always aerated. Fermentation is controlled via a temperature regulated space. We have essentially tried to cover every last expected variable that might make an impact but nothing has ever really shown any significant changes.
I used to, but then realized my thermometer was 5-6 degrees off, and since switching my beers have been over attenuating. Blanket ways to increase attenuation: 1. Pitch a more attenuative yeast (e.g. Cali Ale versus Cali V ale) 2. Oxygenate with Pure O2 or use aquarium pump with diffusion stone and filter 3. Pitch an adequate amount of yeast (See Mr. Malty or Yeast Calc) 4. Mash Lower (e.g. 148 versus 156) 5. Mash Longer (90 minutes versus 60 minutes; longer mash may also result in less sweetness) 6. Reduce crystal malt or unfermentables in recipe (e.g. replace some crystal malt or flaked grain with base malt) 7. Replace a portion of base malt with Sugar (e.g. remove 5% of base malt and replace with corn sugar; Adding sugar will not lower FG, replacing malt with sugar will) 8. Get an accurate thermometer (See statement before list)
Do you start fermentation with addition of oxygen into the wort? My own attenuation improved when I did this simple and inexpensive change to my system. Edit: man some of y'all are quick
General efficiency is right about 80% and with some simple calculations we know we are always right about where the expected OG should be and where the FG should then come out to based on strain etc. Typically it is a very small difference, say an expected of 12 and an actual of 14 but it is those very last few that would be nice to drop.
My personal perspective of attenuation is that while there are a number of factors (kudos to barfdiggs on his comprehensive list) but the two most important aspects are: · Fermentability of the wort · Attenuation capability of the yeast used So, for an all grain brewer the ‘best’ way to obtain a fermentable wort is to mash at a lower temperature for an extended period of time: mash at 148-150°F for 75-90 minutes. Also, do not use a lot of crystal malt in the grist since crystal malt adds a lot of unfermentable sugars. Select a yeast that is attenuative. An example of a yeast which is highly attenuating (but not applicable for many beer styles) is Wyeast 3711 (French Saison). Wyeast 3711will metabolize almost every type of sugar and if you use this yeast to brew a Saison grist will often end up with a Final Gravity like 1.001. As bardiggs mentioned a very good general purpose yeast that is attenuative is the California Ale yeast; I prefer the US-05 version of this yeast. Cheers!
Efficiency is a measure of the ability of the mash to convert starches to sugars. Having an efficiency of 80% is good. Efficiency does not a measure of the fermentability of the wort. For example, you may get a conversion of starches to sugars of 80% but a significant portion of those sugars may be unfermentable sugars depending on the yeast strain used. Examples of sugars which may be unfermentable are maltotriose (yeast strain dependant) and dextrins. You need to be concerned about how you mash is creating a fermentable wort. Cheers!
I think the most important question is do you like how your beers taste? Everything else is secondary.
Exactly, everything else is secondary. Taste is almost always great and when it is off slightly it isn't due to that. Just working to try to fine tune and really perfect our process to get the exact expected results when possible.
Maltotriose is indeed a sugar that most yeast strains cannot ferment completely. But most strains can ferment maltotriose partially. And it's their relative abilities to ferment maltotriose that's responsible for the varied typical attenuation ranges of each strain. Wort also contains higher long chain 'sugars' (dextrins) that no S. cerevisiae strains can ferment. So, the fermentability of the wort depends largely on the ratio of these dextrins to the fermentable (and partially fermentable) sugars. These unfermentable dextrins include maltotetraose, maltopentaose, and a whole bunch of other things that are a bitch to spell.
1) There's no prize for hitting an 'expected' FG. If you are happy with what your senses are telling you, why in the world would you want to change something just to hit a number? 2) FG predictions by software are not very good, for a number of reasons.
This is perfect and fits with what I had generally expected especially when going back through brewing notes and recipes. Thanks a bunch for all of the input.
I've used these methods and working great. I don't aerate except on transfer and after wort chiller and getting great attentuation 1. Pitching bigger starters 2 Mash Lower (e.g. 148 or 150) think this may have biggest impact 3. Mash Longer (I've been doing 90 & 80 minutes) 4. Using some corn sugar to get dryer beer (1/2 lb for 5-6 gal batches)
As I stated: “Examples of sugars which may be unfermentable are maltotriose (yeast strain dependent) and dextrins.” Cheers!
Yes, you did. Somehow I missed the 'and dextrins' part. Did you edit? Either that or I inadvertently edited you in my quote. Edit: yes you did. There's no way I changed 'are' to 'is.' No big deal. I just added to what you originally said, and so did you.
I would look at a couple of things in your process (since you don't want to post any of it) 1. What's your yeast count? Are you under pitching? mrmalty.com 2. Grainbill. are you using too many crystal malts/adjuncts? 3. Mash temp. Are you too high? Check the calibration of your thermometer in ice water for 10 minutes and check your boil point. 4. Aeration. Are you properly aerating when you pitch? 5. Fermentation temp: Does it fluctuate, or drop down more than a few degrees per day? You might be shocking your yeast. 6. Vocals. When you sing to your beer do you miss or hum words that indicate you forgot the lyrics?
To the OP. Wisdom in this post. Taste is indeed the thing. Chasing a FG target may change your beer in other, less desirable ways. That said, for me making starters and aeration are the two most important keys to having the yeast do what they are capable of. A 2 hour, single infusion mash right around 150 F also seems to make a very fermentable wort.
