smell identity?

[Gurgeh]

There's a whiff I've occasionally found when AG-ing, which I didn't get as an extract brewer.

In my current brew I have it - it seems to be related to the muck i've skimmed off at the start of fermentation. i've now skimmed three times since pitching and the smell seems to be abating. the trub i took away reeked of it.

On my first ever AG i remember that I didn't skim at all and the smell lingered - the taste was awful. I (wrongly) put it down to infection and tipped it.

I had it last time i did this brew:

20L

5KG MO
300g chocolate malt
60g black malt

225g black treacle
60g x 60mins Brewers Gold.


The smell and taste went altogether last time (about 6 weeks), and it ended up being astonishingly good.

so i've done it again yesterday and the smell is back!

so what is the taste/smell - it could be described as 'meaty' (think a pungent overcooked roast beef or a sort of gacky beef stock - i just can't put my finger on it) and what is the generally accepted term for describing it (i.e. diacetyl is 'butterscotch').

I'm hesitant to think it's just hop bitterness as that first brew i binned had only 40g brewers gold for 60mins and 20g brewers gold for 15 mins.

bearing in mind that with time the smell & taste will entirely disappear, is this just 'green' and if so why do other recipes have different green-ness?

This one really does vex me

[steve_flack]

How do you cool your wort and what yeast do you use? Is is the same for extract and AG batches?

[Gurgeh]

How do you cool your wort and what yeast do you use? Is is the same for extract and AG batches?

I use an IC, and the smell is the same regardless of whether the yeast is SO4, charles wells or crouch vale...

The update is that the smell has pretty much cleared from my current fermentation, so skimming the top has had a massive effect. an that skimming has been made a damn sight easier by leaving the lid off the FV for the first time ever!