Fermenting in the kettle on all the trub?

[nallum]

I thought I'd be a lazy ******* out of curiosity and ferment on all the trub in my kettle after chilling to pitching temperature. Did a little literature review and it seems trub is actually nutritious for brewer's yeast and can even act as flocculation nuclei to aid clearing during conditioning. Obviously, commercial brewers don't do this because they soon need the kettle for boiling the next batch of wort to stay in business. I started to believe there might actually be something in this for home brewers, though. Why not?

So I reasoned the best way to assess things was to make a simple recipe I’m familiar with that’s difficult to hide faults. A simple lager. Pilsner malt 100%, Magnum for bittering and some late Saaz. Fermentation proceeded as usual with expected FG reached on time. The only differences I noted were lots of hoppy-looking debris on top of the yeast head and, after fermentation, clearing seemed to take longer than usual. So much for the ‘flocculation nuclei’.

I did a side-by-side comparison using the same batch of pilsner malt, hops and freshly harvested lager yeast. The only difference being it got transferred off the kettle trub into an FV, as per standard method, the day before. Otherwise I’m confident the procedure was comparable for both brews.

Both beers were transferred to kegs and lagered for 4 weeks at 2℃ +/- 1℃.

From the time of kegging, which I delayed for a few days hoping the beer fermented in the kettle was going to clear more, there was a noticeable difference between the two. The kettle fermented brew was more opaque with a heavier mouthfeel and a weird subtle ‘manure’ like aroma. It was too early to conclude anything though, beer changes dramatically during conditioning over a week or so.

Four weeks later, I had two bright and nicely carbonated lagers. But the kettle fermented brew was noticeably different. Not a drain pourer by any means, but not the expected nice crisp lager. It still had a heavier mouthfeel, a subtle hint of ‘manure’ (biased by my senses’ memory?*) and left a sense of a coating on my teeth. I’m guessing there was a shedload of additional protein or something else in the kettle fermented beer relative to the beer transferred to an FV.

Conclusion: personally, it’s not something I’ll be aiming to do again.

*I brushed my teeth, just to be sure.

[IPA]

Most interesting.
Thanks for sharing the result

Ian

[guypettigrew]

Fascinating. Thanks for taking the risk and posting your result. Good to know the lager is drinkable and won't need throwing away!

Guy

[nallum]

Good to know the lager is drinkable and won't need throwing away!

Bottled it and gave it away. Kept the good stuff.

[PeeBee]

Fascinating. Thanks for taking the risk and posting your result. Good to know the lager is drinkable and won't need throwing away!

Guy

Fascinating? Add me too!

I've long considered leaving the beer in the boiler to ferment (do you - "nallum" - leave it to cool naturally or rapidly with a cooler or like?), but I've never been brave enough to try it myself.

Bit disappointed the beer don't turn out as good done like that. Ah ... poo. ("Mashbag" isn't going to be happy ... he's always trying to get us doing it).

Thanks for trying it out, writing it up, and saving me the trouble (I don't need "curiosity" to make me "a lazy ******* "). But "bottled it and gave it away" ... I wouldn't want to be doing that either! ... Ah, is that why "Mashbag" wants us all doing it?

[nallum]

Here’s a pic I forgot to add of the hoppy debris on top of the krausen.

IMG_0565.jpeg (2.02 MiB) Viewed 1967 times

Looks more like a compost heap.

[guypettigrew]

Oooh, wonderfully horrible!!

Guy

[clarets7]

Didn't Mashbag promote this idea a few years ago? Mind you, a lager style might not be as forgiving as an ale.

[MashBag]

MashBag does this all the time

In fact it's hard method to get away from.
But it is more than just fermenting it in your kettle.
It did require more than one go to get right, and I have never tried it with Lager par se. I have also never binned one.

The observation I will make is I would never leave it 4 weeks. Was that an oversight?
Thinking about it I would genuinely expect that to get a "heavier mouthfeel and a weird subtle ‘manure’ like Aroma" or to bin it. Tbh I think you got lucky.

Beer doesn't stop changing, just cos the yeast has finished. And you have a lot of other stuff in there. Trub, Lees, sediment call it what you will, but its all still 'going' in some way. It does compost in effect.
Timely racking is a must (pardon the pun) for all beverages.
Racking it off & accurate temp control (+/– 0.3°c) are important flavour controls.

@nallum If you want to do it again I am happy to help, I would genuinely like to prove you can make a quality lager. I make a summer ale, which is very close.

[MashBag]

Here’s a pic I forgot to add of the hoppy debris on top of the krausen.
IMG_0565.jpeg
Looks more like a compost heap.

Is that a braumeister?

[nallum]

Fermentation took 5 days at 12*C, after oxygenating wort with pure O2 then pitching freshly harvested Diamond Lager yeast at the same temperature (12*C). OG was 1.044 and finished at 1.008 early day 5. Cooled to 5*C for 2+3 days to clear for kegging. The extra 3 days were added because the green beer had too much suspended solids. Although I was unable to observe it here, I suspect residual yeast activity in the sediment bed was kicking up more trub compared with the same beer fermented from wort separated from kettle trub.

I don’t plan on trying it again, but if I did I’d perhaps use whole hops and a hop spider to remove the hops from the fermentation stage. Intuitively, it just doesn’t seem to be good practice to have so much spent hop debris present in a fermentation for a week or two. The subtle ‘manure’ aroma could be described as ‘vegetal’ I guess. It’s not a character I like or want in my beers, tbh. I’m not a fan of drop hopping either. The closet I get to dry hopping, even for IPAs, is a post-boil hop stand at 80*C for 15 minutes or so. My beers are probably far too balanced and boring for new age hop heads.

[nallum]

Is that a braumeister?

Yes, it is a Braumeister.

IMG_0596.jpeg (2.31 MiB) Viewed 1868 times

The fermentation itself proceeded very well, the Braumeister coming into its own with the onboard PID temperature control and cooling jacket. I was quietly surprised, tbh. It was the most precisely controlled fermentation temperature I’ve ever seen. 12.0*C +/- 0.1*C then, as the PID solved the environmental puzzle, settled at a continuous 11.9*C.

IMG_0574.jpeg (3.04 MiB) Viewed 1867 times

If I didn’t have a temp controlled ferm chamber it would be worth the extra effort to rack off the wort from the kettle trub, rinse the Braumeister then transfer the wort back. Definitely.

[MashBag]

...... if I did I’d perhaps use whole hops and a hop spider to remove the hops from the fermentation stage.

My bad, I missed that.
You absolutely cannot leave the hops in.
I use pellets and a spider. These must be out even before chilling. That explains a lot.

[MashBag]

Ooo a popper new shiney one.

That will defo do it. Designed by braumeister to do it.

Mine was a handme down BM from Noah, which I modified and gave them the ideas.

Did you get the chiller pack too?

[nallum]

I did wonder about the hops. My initial plan was to use whole hops in my hop spider then remove them, but, for the recipe used, I only had hop pellets to hand and my spider mesh is no good for pellets. I might give it another go then.

No, I didn’t get chiller pack. Works fine with cold tap water to chill wort from the boil and a keg of very cold water in my fridge for fermentation, even without an insulation jacket on the BM, water use was very low to maintain fermentation temperature. And I didn’t get all that excessive condensation glycol chillers often promote.

In fact, I’ve decided to give it another go. I’ve got some English Lagers to brew for the summer and loads of whole Goldings hops to use up. Hopefully a more successful attempt.