Excess Trub In Fermentation

[marky_mark]

Hey Guys,
I've been deliberating for a while now over the root cause of some mild yet noticeable rancid vegetal flavours and aromas that I have in at least two batches now. I am still open to possibility that it could be an infection or DMS, however I am less and less inclined to think the former. Mainly because it does not seem to be getting appreciably worse, in fact the opposite over time and as I vent the kegs.

Since I bought a shiny new plate chiller from Craftbrewer several months ago I have been forced to let the hot wort sit in the kettle post flame out while the whirlpool settles the trub into a nice firm cone. After this I run off through the chiller into the fermenter. The wort only sits hot for around 5-15 min and I do a 90 min boil on beers with a large portion of pilsner malt in the grist. So I am starting to think it is not DMS, despite those hallmark rancid vegetal flavours. With the beers in question I had noticed that the resulting layer of trub in the fermenter was quite thick. Additionally, these beers included more hops that most.

My question is has anyone experienced any rancid vegetal type aromas or flavours from letting their beer ferment on a large amount of hop and break material, particularly with lagers which will naturally spend more time in primary fermentation?

 

[crundle]

Not sure about lagers in particular, as I haven't brewed any, but I BIAB, which generates a fair amount of break material, and I no chill cube, putting all the cube contents (including cold break) into the fermenter to ferment. I haven't experienced these flavours you speak of, so I would say it isn't the cold break, and I am assuming that your whirlpooling is not allowing much hot break to get through either. The extra trub in the bottom of the fermenter sounds like cold break. Does it start off fairly 'fluffy' and take up quite a volume of the fermenter, then compact over the fermentation?

Do you use a hop bag, or throw them directly into the wort? The vegetal flavours may come from hop material that is making its way through, especially if it is a late hop addition (but perhaps not rancid smelling).

If the problem has been around for several batches, can you think of anything in your process that may have changed at the time, such as sanitation or your procedures?

Crundle

 

[muckanic]

My question is has anyone experienced any rancid vegetal type aromas or flavours from letting their beer ferment on a large amount of hop and break material, particularly with lagers which will naturally spend more time in primary fermentation?

I have always noticed more sulphides in the ferment whenever some hot break has made it through. Not, however, with cold break. Most of it usually scrubs out. This is all from an ale perspective, nb.