Death to secondary fermentation!

[Singletrack]

As long as the fermentation completes and proper attenuation is achieved then why do I care how much faster the ferment is with the trub in there. I'm not running a production line.

My takeaway from that study is a big yawn, what I really wanted to know is a quantitative study of leaving the beer on the trub for say a month or more. Will the off-flavors caused by the trub disappear over time if left on the trub, will they stay the same or will they increase for one or more reasons, like autolysis of the yeast. Does anyone know if such a study has been done (other than the one by brulosophy)?

The study seems to be discussing the effects of BK (wort) trub on primary fermentation. There is no discussion of fermentation trub and its effects, which is why I mentioned that this may be off topic. Whether or not you use a secondary vessel, the effects of wort trub during fermentation will be the same.

It is possible that leaving the beer on the trub, instead of racking to a secondary, could impact the off flavors that resulted from fermentation of the wort trub, but this study is silent on that subject, as you said. (...so I'm not sure why you posted it to begin with, but I'm glad you did.)

The only off flavor mentioned in the study is fusel alcohol. (Depressed esters are another effect, but not really an off flavor.) My understating is that, once formed, fusel alcohols cannot be cleaned up. I'm guessing that means leaving the beer on the trub makes no difference. Esters are unlikely to be impacted by more time on the trub too, I think.

I don't know of other studies about the effects of leaving the beer on the fermentation trub, but there is a lot of anecdotal evidence suggesting it doesn't have a significant impact whether you leave the beer in the primary for one week or four.

I have continued to use a secondary for dry hopping, but that doesn't seem necessary either.

 

[jethro55]

Yep I agree. It doesn't address 'how slow can I make a beer with all the trub and not affect flavor'. But it does say that trub affects flavor. And that more trub is a negative flavor impact in production brewing. Barely relates to the idea of secondary.

Dry hopping in secondary is a choice - not a requirement.

 

[hopbrad]

No way hopbrad !! That's the best thing that you can do ! The best thing that I can do is mash hop a heavy load of my fresh homegrown centennials and add a heavy load of fresh hop tea (done ever so carefully) at bottling time.

Touchee!

 

[RM-MN]

Results indicated that trub stimulated yeast activity, and subsequently, the rate of fermentation. In addition, elevated trub levels depressed the formation of esters and slightly increased production of fusel alcohol. Flavor analyses of the finished product demonstrated a preference for beers produced from clarified worts. The relationship between trub and fermentation kinetics appeared to be related to high lipid and zinc contents in the trub, which may have contributed important growth factors to the yeast.

We tend to think of off flavors in our beer being related to the excess production of esters which we call "banana" or "bubblegum". Fusel alcohol is usually considered separately from "off flavors" . This study says that the beer fermented on trub has less esters which should mean a cleaner flavored beer but then it says that flavor analyses of the finished beer demonstrated a preference for beers that were produced with clarified worts.

OK, which is it? Do we prefer beers with less esters or more esters or is the presence of fusel alcohols overwhelming the presence of esters? The meat of the study and the conclusions seem to be at odds.

 

[jethro55]

Fusel alcohol flavors I have perceived in barely finished beers before bottled. Not sure if it was chemistry, but it seemed that the harshness disappeared after a few days.

I think that production brewing, even for craft beer, needs to be exact when it comes to flavor. It comes down to getting so many people used to a good flavor (so much subjective) and repeating it. Being of 'good' taste and consistently the same is repeat business.

The study said that the amount of trub affects the rate of attenuation. That makes sense with our temperature control issues and experiential flavor results in homebrewing

 

[jethro55]

One could assume from the findings that a full kettle dump fermented at lower temps is the same flavor as a cleared dump fermented at higher temps. It's a stretch of info admittedly.

 

[huckbof]

The study seems to be discussing the effects of BK (wort) trub on primary fermentation. There is no discussion of fermentation trub and its effects, which is why I mentioned that this may be off topic. Whether or not you use a secondary vessel, the effects of wort trub during fermentation will be the same.

Maybe/maybe not, some of us rack off the trub to secondary just after high krausen, in cases like that using a secondary could minimize some of the effects of the trub on taste because it was on the trub for such a short period. Look at my #7 post.

"Worts with high trub content were produced by omitting clarification treatment altogether" this suggests to me that the wort trub goes into the fermentor and thus becomes fermentor trub. Since the response variable is taste it makes sense that fermentation trub was also present in all cases but not a significant factor because they did not relate it to taste, at least not what is in the abstract, the actual study may say different.

My understating is that, once formed, fusel alcohols cannot be cleaned up. I'm guessing that means leaving the beer on the trub makes no difference.

I don't think I would make that conclusion, if trub caused fusel in this study then it may be reasonable to assume that the longer the beer is in contact with the trub, the more likely you are to form more fusels. And if the fusels don't clean up then the argument that leaving the beer in primary for 4 to 5 weeks or more in order to clean up the beer is false when it comes to fusels.
Check out this link that says "it is possible for fusel alcohols to arise from oxidation or from leaving the beer sitting on the trub in the fermenter for a really long time."

http://drinks.seriouseats.com/2013/12/homebrew-troubleshooting-off-flavors-from-yeast-how-to-fix-phenols-solventy-flavor-diacetyl-sanitizing-tips.html

This study was from 1982, surely there are more recent/relevant studies, are there any members of the ASBC out there that can comment or point us to other information sources?

 

[MattyIce]

Here is an interesting tidbit from the book "Yeast"



I rarely transfer to a seconday. It usually is something that will age for a long time, like my Brett beers and sours. I do this mostly to get them out of the buckets for aging. I have many 5 gallon carboys that I can set aside and age for a long time and not miss them.

Even those beers that have been tranferred and aged for months never have any problem carbing up.

I learned a lot from that book!