THP (Tetrahydropyridines)

[RPh_Guy]

I saw this great article and wanted to share:
https://www.goodbeerhunting.com/blo...-is-bad-for-beer-and-what-you-can-do-about-it

Further reading:
http://www.milkthefunk.com/wiki/Tetrahydropyridine
https://www.lambic.info/Tetrahydropyridines

Can we as a community help figure out how to avoid THP?
Do you get THP in some mixed sours but not others?
How long does yours take to age away if it appears?

 

[sweetcell]

THP is evil. i'm particularly sensitive to it and i HATE the taste.

> 1. Can we as a community help figure out how to avoid THP?

i'm resigned to it. nothing i've tried seems to prevent it. i don't think anyone truly understands exactly how THP is produced, so controlling it is going to be hard...

the best explanation that i've heard, and it jives with my experience, is THP is produced (mostly by brett) after the bugs have been in the stressful enviro of a long-aged beer (low nutrient and alcoholic), and then are suddenly exposed to both food and oxygen. during bottling, you are typically adding priming sugar (food) and the beer is exposed to O2 in the bottling bucket, the bottle, etc. - boom, THP.

> 2. Do you get THP in some mixed sours but not others?

i get THP is the vast majority of my sours. in fact, i can't remember a recent one that hasn't had THP. maybe some of my earlier sours didn't have it, but i suspect i just didn't recognize it or wasn't sensitive to it at the time.

> 3. How long does yours take to age away if it appears?

on average, 6-8 weeks. one particular beer took more than 3 months - at first it was undrinkable, later aged out to be one of my favorite sours ever.

some people can't detect THP. i had a fellow beer nerd who had no problem with the above-mentioned 3-monther when i was fresh, while i was drain-pouring mine.

 

[RPh_Guy]

some people can't detect THP.

Those lucky bastards.

Oddly enough, THP is also a common issue in kettle sours.
Is THP ever a problem in Brett beers without Lacto? I've never heard of that happening.
This makes me wonder if THP production has something to do with Lacto cells dying and then some compound(?) oxidizing before or after being modified by Sacc somehow.
It seems some species of Lacto are more prone to producing it.

My own experience is rather limited.
My wild ale (the only Brett mixed sour I've bottled so far) has some after I've bottled it, but more of a bread-like background flavor. Unfortunately the beer was radically different (worse) within a week or two after bottling.
It's still not great 2 months after bottling. I'm hoping it goes away...

Here's the plan to minimize oxygen uptake during my next sour bottling day:
1. Bottle directly from fermenter into primed 22oz glass bottles via bottling wand.
2. Minimize bottle headspace (I have no easy way to purge).
3. Add Premier Cuvee (wine yeast) to each bottle.
4. Activate oxygen-absorbing caps after capping.

Plans for the future:
Experiment with different LAB cultures
LODO sours plus quick bottling.

Any thoughts on this? Successes or failures?

 

[sweetcell]

Is THP ever a problem in Brett beers without Lacto? I've never heard of that happening.

i'm sitting on 5 gallons of proof that lacto is not required: i have a brett-only saison that has it bad. no lacto in the beer. based on what i've read in MTF, brett is the main and most reliable producer of THP in a mixed fermentation.

This makes me wonder if THP production has something to do with Lacto cells dying and then some compound(?) oxidizing before or after being modified by Sacc somehow.
It seems some species of Lacto are more prone to producing it.

possible, the MTF wiki says something along those lines... but i've never done a kettle sour, so can't contribute much there.

Here's the plan to minimize oxygen uptake during my next sour bottling day:
1. Bottle directly from fermenter into primed 22oz glass bottles via bottling wand.
2. Minimize bottle headspace (I have no easy way to purge).
3. Add Premier Cuvee (wine yeast) to each bottle.
4. Activate oxygen-absorbing caps after capping.

of the above steps, #3 will do the most to suppress THP, IMO. i forgot to mention that every time i get THP in my sours, i didn't add sacch at bottling - i let the brett carbonate the beer. adding wine/champagne yeast at bottling = no THP all the time every time. i believe this is due to sacch being so much faster than brett, so there isn't any sugar left by the time the brett wakes up.

 

[RPh_Guy]

Thanks. I guess I'll see how it goes.

 

[dmtaylor]

I like Cheese Nips in my sours. I do not like it in my ciders though.

 

[DrKnow]

Acid shock starters for bottling yeast (search milk the funk wiki under “packaging”) have eliminated THP in my bottled sours. Or coincidentally I haven’t had THP develop since I began using the technique a couple years ago. I have even had some beers fully carbed and ready to drink in as little as 5 days. It’s some extra work in the days leading up to bottling, but it really seems to pay off in the long run.

 

[RPh_Guy]

Acid shock starters for bottling yeast (search milk the funk wiki under “packaging”) have eliminated THP in my bottled sours. Or coincidentally I haven’t had THP develop since I began using the technique a couple years ago. I have even had some beers fully carbed and ready to drink in as little as 5 days. It’s some extra work in the days leading up to bottling, but it really seems to pay off in the long run.

What yeast do you use for bottling?

Do you use the procedure described in the wiki, with multiple steps? Or only one acid step like the rare barrel?

 

[NBBC13]

Those lucky bastards.

Oddly enough, THP is also a common issue in kettle sours.
Is THP ever a problem in Brett beers without Lacto? I've never heard of that happening.
This makes me wonder if THP production has something to do with Lacto cells dying and then some compound(?) oxidizing before or after being modified by Sacc somehow.
It seems some species of Lacto are more prone to producing it.

My own experience is rather limited.
My wild ale (the only Brett mixed sour I've bottled so far) has some after I've bottled it, but more of a bread-like background flavor. Unfortunately the beer was radically different (worse) within a week or two after bottling.
It's still not great 2 months after bottling. I'm hoping it goes away...

Here's the plan to minimize oxygen uptake during my next sour bottling day:
1. Bottle directly from fermenter into primed 22oz glass bottles via bottling wand.
2. Minimize bottle headspace (I have no easy way to purge).
3. Add Premier Cuvee (wine yeast) to each bottle.
4. Activate oxygen-absorbing caps after capping.

Plans for the future:
Experiment with different LAB cultures
LODO sours plus quick bottling.

Any thoughts on this? Successes or failures?

not much experience, just starting sours about a year ago, just my two cents as organic chemist.
from what I can find, the mousy flavors come from 2-ethyltetrahydropyridine and N-acetyltetrahydropyridine (as well as 2-acetyl-1-pyrroline). N-acetyl THP is oxidized form of 2-ethyl THP. THP itself is the hydrolyzed version of N-acetyl THP.

Studies have shown that N-acetyl-THP is produced from Lacto. comes from precursors such as lysine and requires fructose and ethanol as well.
THP is not an oxidative by-product, it's actually a reductive by-product in the final step. However, the previous step in the biosynthetic pathway is driven by conversion of NAD+ to NADH (oxidation). One paper I read stated the process requires iron (maybe in the bacteria). my guess is that the iron is chelating oxygen and delivers it into the metabolic cycle. bottom line, process could be a metabolite from oxygen driven metabolism in lacto, so removing oxygen might slow down this metabolic pathway

 

[sweetcell]

Acid shock starters for bottling yeast (search milk the funk wiki under “packaging”) have eliminated THP in my bottled sours. Or coincidentally I haven’t had THP develop since I began using the technique a couple years ago. I have even had some beers fully carbed and ready to drink in as little as 5 days. It’s some extra work in the days leading up to bottling, but it really seems to pay off in the long run.

this makes sense to me: you're adding sacch at bottling, thus preventing brett and/or lacto from consuming the sugar and producing THP. if this is the case, then the acid shock pre-treatment isn't suppressing THP per se - it's just setting up the sacch for success.

 

[DrKnow]

What yeast do you use for bottling?

Do you use the procedure described in the wiki, with multiple steps? Or only one acid step like the rare barrel?

I’ve used ec-1118 mostly. But I have used other random wine yeasts that were in my fridge and even us-05. I follow the “low-tech/homebrew method laid out in the MTF wiki. So it’s a multi step process with more steps depending on the volume you are bottling.

 

[DrKnow]

Not 100% related to THP but something else i’d like to add since we’re talking about off flavors and undrinkable beers: if you have a long term mixed culture beer that you plan to rack onto fruit or otherwise kick up a re-fermentation, it helps tremendously to add a super active fresh yeast culture at that time (sacch or Brett, pick your poison). You can even hit your fruit with the fresh yeast a day or two before you rack the beer onto it to really get things going. This might be a little “off topic” for the thread, but since we are discussing ways to avoid off flavors I figured I’d throw it out there. I’ve ruined a couple very expensive fruited sours by depending on the old tired yeast/bugs that are present in the aged beer to re-ferment the fruit.

 

[RPh_Guy]

Good advice, that makes a lot of sense.
Thanks again!

 

[couchsending]

I’d had never tasted it until last week when I had some beers two days in a row that had it, both homebrews. First one wasn’t bad, second one was so overpowering I couldn’t believe the guy served it to anyone. A total THP bomb.

I’ve bottled maybe 6 mixed ferment beers that are generally sacch primary and three or so months of Brett secondary. I always reyeast with either CBC-1, 1118, or T-58 at bottling. I haven’t experienced any THP yet. My process is to close transfer through purged lines to a very well purged keg. Once full I’ll unscrew the PRV and add sugar/yeast through that, reattach PRV and purge headspace, then bottle with a bottling gun off the keg.

Got a few more beers coming up on 9 and 12 months that I’ll be bottling soon. Interested to see if it rears it’s ugly head with those beers.

 

[Qhrumphf]

All my mixed ferms, and Sacch primary/Brett secondary ferms have aged so long prior to packaging that I never picked it up that I can recall. I recall picking up notes early on with 100% Brett beers (Brux and Lambicus at the time but I think nomenclature has changed) I didn't recognize at the time but now I can say was possibly THP (Cheerios was about right) but aged out after a few months. Had a wild (spontaneous) cider exhibit a nasty mousey note (again didn't know it at the time but again sounds like THP) between 1-3 months (racked off lees around that first month) that had aged out when packaged month 5 or 6. All my small scale kettle sours have exhibited it to one degree or another, not major but noticeable.

I'm not familiar with the mechanisms behind it and I don't mind the cereal expression if it, but the mouse/hamster cage character is gross.

 

[NBBC13]

Not 100% related to THP but something else i’d like to add since we’re talking about off flavors and undrinkable beers: if you have a long term mixed culture beer that you plan to rack onto fruit or otherwise kick up a re-fermentation, it helps tremendously to add a super active fresh yeast culture at that time (sacch or Brett, pick your poison). You can even hit your fruit with the fresh yeast a day or two before you rack the beer onto it to really get things going. This might be a little “off topic” for the thread, but since we are discussing ways to avoid off flavors I figured I’d throw it out there. I’ve ruined a couple very expensive fruited sours by depending on the old tired yeast/bugs that are present in the aged beer to re-ferment the fruit.

So, by "super active fresh yeast culture (sacch or Brett)", is there a simple one you use from LHBS or do make a starter out of dregs? Or could you use the same strain you threw in after fermentation. e.g., I used Belgian Sour Mix WLP655 after transferring the fermented wort to our barrel. that strains contains lacto and Pedio on top of the brett and sacch

 

[DrKnow]

The important thing is you are looking for a healthy YEAST culture to ferment out the sugars from the fruit. It can be as simple as a pack of US05. If you want to use a liquid culture, I would do a starter.

 

[NBBC13]

The important thing is you are looking for a healthy YEAST culture to ferment out the sugars from the fruit. It can be as simple as a pack of US05. If you want to use a liquid culture, I would do a starter.

thx, that's helpful.

 

[toddo97]

Not 100% related to THP but something else i’d like to add since we’re talking about off flavors and undrinkable beers: if you have a long term mixed culture beer that you plan to rack onto fruit or otherwise kick up a re-fermentation, it helps tremendously to add a super active fresh yeast culture at that time (sacch or Brett, pick your poison). You can even hit your fruit with the fresh yeast a day or two before you rack the beer onto it to really get things going. This might be a little “off topic” for the thread, but since we are discussing ways to avoid off flavors I figured I’d throw it out there. I’ve ruined a couple very expensive fruited sours by depending on the old tired yeast/bugs that are present in the aged beer to re-ferment the fruit.

Great advice--that's a 'why didn't i think of that' thing, but something I'll keep in mind from now on

 

[sweetcell]

Not 100% related to THP but something else i’d like to add since we’re talking about off flavors and undrinkable beers: if you have a long term mixed culture beer that you plan to rack onto fruit or otherwise kick up a re-fermentation, it helps tremendously to add a super active fresh yeast culture at that time (sacch or Brett, pick your poison). You can even hit your fruit with the fresh yeast a day or two before you rack the beer onto it to really get things going. This might be a little “off topic” for the thread, but since we are discussing ways to avoid off flavors I figured I’d throw it out there. I’ve ruined a couple very expensive fruited sours by depending on the old tired yeast/bugs that are present in the aged beer to re-ferment the fruit.

alternative: a week or two before i fruit my sours, i add a little boiled sugar. i then wait for the brett to become active again before racking on to the fruit.

I’ve ruined a couple very expensive fruited sours by depending on the old tired yeast/bugs that are present in the aged beer to re-ferment the fruit.

interesting - how did those beers taste? can you describe the off-flavor?

even before i started adding sugar to wake up the brett, my sours have always kicked up upon fruiting without fresh yeast and have fermented out the fruit.

 

[DrKnow]

How did those beers taste? Anywhere from acetic acid to 80’s sporting goods store. A giant pile of tires on fire, while someone is throwing plastic and styrofoam on the top to keep that good black smoke going. You know, the type of thing that’s probably not going to age out. Mostly just “weird but not in a good way” type of flavors. Not the pleasant kind of funk by any stretch of the imagination. More the kind that would scar the uninitiated for life. Just terrible stuff that I had to dump down the drain while I was alone so no one ever knew it existed. All the while feeling the shame of spending $50-$60 on fruit to put into a beer that was “exceptional” before I messed with it. So I adopted the practices of:
1. Fresh yeast of some kind when you add fruit/sugar
2. Acid shock starters when bottling
Anecdotal evidence perhaps. But I haven’t dumped any beer that has survived the aging/packaging process in a few years (and I make a lot of sour/funky beers). So it works for me. Fresh yeast certainly isn’t going to hurt your cause.

 

[RPh_Guy]

I got a small taste of your pain, from laughing so hard!

That's a real bummer though, I'm sure it wasn't funny at the time. Thanks again for the tip.

I'm thinking I want to just use lactic acid for my acid shock starter, rather than using my sour beer to acidify it. I'd much rather get out my pH meter rather than disturb my little friends.

 

[505-Brewer]

alternative: a week or two before i fruit my sours, i add a little boiled sugar. i then wait for the brett to become active again before racking on to the fruit.


interesting - how did those beers taste? can you describe the off-flavor?

even before i started adding sugar to wake up the brett, my sours have always kicked up upon fruiting without fresh yeast and have fermented out the fruit.

Mine too. Never had an issue but often I fruit a new blend so there’s likely newer beer w yeast around to do the work. Might have to try this approach next time.

 

[goodolarchie]

Some very interesting outcomes here. This year I wanted to try experimenting with the existing Brett vs pitching Champagne yeast (ec-1118), initial results vs over time.

So I've done that, twice now. Consistently the wine yeast beer is quite nice after only 3-4 weeks. Certainly no THP. The Brett makes a better pour and lasting head, mouthfeel in my opinion, but the THP is there. Over time my hunch is that the Brett bottles will prove to be a better expression, more complex, etc. EC-1118 is a killer strain through so the real question is does that prevent any meaningful bottle conditioning of Brett.

Bottom line is if I was bottling for a competition (my equivalent of packaging for consumers) that was a month away, I'd use wine yeast and not bat an eye.

I also recently spoke with a pro who stopped using Brett in primary for their flagship table saison, only when priming for bottle conditioning. Not just to avoid THP but the Brett contribution was greater and cleaner than co-fermentation. Orval does this too, for what it's worth.

My goal next year is to identify a great Brett strain for bottling, maintain enough of it isolated that it can always go in kegs or bottles for conditioning clean and quickly.

 

[couchsending]

Killer factor of Sacch only has an affect on other Sacch strains, not Brett or any other species of yeast.

 

[RPh_Guy]

The Brett makes a better pour and lasting head, mouthfeel in my opinion, but the THP is there. Over time my hunch is that the Brett bottles will prove to be a better expression, more complex, etc.

The only way to determine the effect of a variable is with a blind tasting. With THP present, it makes more subtle comparisons unblinded.

Thanks for experimenting like this. I'm glad to hear another case where the wine yeast is having a beneficial effect with regard to THP. I'd love to hear the results of a blind comparison once the THP is undetectable!

I also recently spoke with a pro who stopped using Brett in primary for their flagship table saison, only when priming for bottle conditioning. Not just to avoid THP but the Brett contribution was greater and cleaner than co-fermentation. Orval does this too, for what it's worth.

My goal next year is to identify a great Brett strain for bottling, maintain enough of it isolated that it can always go in kegs or bottles for conditioning clean and quickly.

Flavor:
Micro-aeration easily explains the increased Brett contribution in bottles. Brett needs oxygen exposure, and bottles let in a fair amount (unlike commercial primary stainless steel vessels). As homebrewers we have the option of using plastic fermenting vessels, which provide a healthy amount of oxygen for relatively rapid flavor development in bulk.

Bottling with Brett:
I routinely add Brett at bottling, but only to batches that also had Brett in primary. It takes 3-4 months for the flavor to really develop after bottling. I keep my bottles 65-70°F.
My last batch I split it into 12 smaller batches, each with a different Brett culture.

Yeast ranching:
I maintain a ranch of mixed cultures and isolates in mason jars at room temp. At bottling I simply add couple drops of the sediment to each bottle using a sanitized dropper. It doesn't need to be recently propogated.

Every 3-6 months I stir, remove 80-90%, and replace with fresh wort. These cultures are loaded with THP so I really don't want to add a lot of it to the batch anyway.

Killer factor of Sacch only has an affect on other Sacch strains, not Brett or any other species of yeast.

Exactly. The bottling yeast in no way inhibits the Brett or bacteria.

 

[goodolarchie]

The only way to determine the effect of a variable is with a blind tasting. With THP present, it makes more subtle comparisons unblinded.

That's the goal (triangle test early next year), but I want a few of my sour beer friends to be there, and a bit more time for the THP to fade. I've heard keeping the bottles slightly above cellar temp is the conventional wisdom for fastest improvement. Not sure why room temp wouldn't work too.

I hope we see some results from the Allagash / Creature Comforts studies on this soon.

My last batch I split it into 12 smaller batches, each with a different Brett culture.

That was my exact plan too! Take a modest mixed-ferm beer, prime, pipette a few mL of slurry from each of several experimental brett isolates I have going, then compare. What were your results there, any standouts?

 

[RPh_Guy]

My 4-month tastings are still ongoing. I can't really sit down and drink a 12-pack of sours while picking out flavor nuances.

Unfortunately I really dislike the Brett strain I used for the most recent base beer: TYB Lochristi Blend. It tastes like overripe strawberry (not in a good way), and strong sweat (also not in a good way). Sacc was WLP644, which always performs well, giving nice tropical pineapple and mango. Also it's pretty sour since I used no hops, for the sake of experimentation.

WY Belgian Lambic blend has given my consistantly great results when used as primary and when added at bottling. It gives nice classic Brett esters and aroma and pleasant vanilla-like phenols.
I like the dregs from Pretentious Barrel House; they give nice tropical fruit flavor.
Three Floyd's Deesko dregs are nice too. Good classic Brett fruity esters and this most recent batch I'm getting a finish a bit like cotton candy.
Jolly Pumpkin dregs give really dominant barnyard character quickly, if you're into that. Leather, wet hay, horse blanket, sweat.

On the other hand I'm getting really poor results from Jackie O's Hockhocking dregs. A little vegetal like olive or celery. A lot of their Brett beers taste like olive, so....

I'm happy to ship dregs for the cost of shipping and materials, or exchange instead.

If you're adding Brett to individual bottles, you definitely don't need a few mL; a couple drops is good, like 0.1mL, and a dropper makes it really easy.

Cheers

I hope we see some results from the Allagash / Creature Comforts studies on this soon.

What studies?

 

[goodolarchie]

Well keep sharing the results... I have most of TYB brett isolates ready to test as well.

What studies?

It was in your original GBH post, which I also found when I first googled THP. There was mention of "the next few months" but I haven't seen anything from either brewery in that time.

 

[RPh_Guy]

It was in your original GBH post

Sorry, I don't know to what you're referring.

I have most of TYB brett isolates ready to test as well

That's cool. I have a couple more interesting-sounding TYB cultures in the fridge that hopefully aren't dead. So little time for brewing.