First Ag (biab)

[dpadden]

"Once you achieve a boil, only partially cover the pot, if at all. Why? Because in wort there are sulfur compounds that evolve and boil off. If they aren't removed during the boil, the can form dimethyl sulfide which contributes a cooked cabbage or corn-like flavor to the beer. If the cover is left on the pot, or left on such that the condensate from the lid can drip back in, then these flavors will have a much greater chance of showing up in the finished beer."

John Palmer

 

[Bribie G]

Thanks Crundle and Paddo, thanks for pointing out my lethal typo ... LID OFF LID OFF LID OFF. Sorry about that. In fact if I put the lid on the Birko as I do in the last few seconds of the boil I have to switch it off at the wall quick smart or I get a wicked boil over.

Too many Coronas. Yes Coronas see 'what's in glass commercial' <_<

 

[crundle]

OK, that's sorted out then, lid off for the boil!

Now to work out what to make next....

Crundle

 

[flattop]

Bad news, i sampled my wort today and it has a slight backtaste of maybe Brett or some infection....
I sanitized everything... Anyhow the flavor is not yet strong so maybe it will pass. The wort was otherwise watery as suspected.
It sits side by side with a kit i am doing that's been on for about 5 days, the it tastes fine the AG not too good.
This does not inspire me with confidence for my first AG, an infection on the first batch would just about be a showstopper for me after fighting an infection in my fermenter last year i ended up throwing it out and buying a new one. This new fermenter has only had one previous brew in it which tasted fine and i stored some starsan in it for the last few weeks as well as putting more starsan on it on brew day.
Anyhow it may not be an infection yet.

 

[Thirsty Boy]

Bring your wort to the boil with the lid on - then once its boiling strongly, take the lid off.

You can leave it "partially" over the top to keep your boil vigor up, but you MUST have a portion open to the air. One of the main things that happens in a boil is that volatile off flavour compounds evaporate and escape to the atmosphere. When you have a lid on - the same volatiles are also some of the first things to condense on the inside of the lid and drip back into the kettle.

If you have a reasonable amount of completely "open" kettle, and you are evaporating around 10% of your starting volume (per hour) - you will have largely boiled off the undesirables. With a lid on - the process will almost certainly be either ineffective or at least much less effective.

You guesstimate of your possible boil off was a fair bit on the high side. In an urn you are probably going to be much closer to 10ish% of your starting volume. In other words 2-3L per hour. The easiest way is to do a test boil. Put 25L of water in that urn and get it to a boil - see how much boils off in an hour... use that figure in your future calculations.

(edit - dammit, missed paddo's post there that says everything I just did anyway... sorry)

 

[Mantis]

Flattop, I just brewed my 12th AG biab today and so far 3 of them I have suspected of being infected from FG sample tastings. They have all turned out great.
I suspect there are flavours there that we are not used to with extract brewing .
I think you will be pleasently suprised

 

[troopa]

Agreed with mantis
Just finished off my 7th Biab today and damn its getting easier( managed to clean 3 cartons of bottles, bottle a brew and rack another secondary all while waiting for the mash )

I have had 3 in there with some strange flavours and all 3 came out great

There was a 4th that was fine till about the 3rd last day and that one vinergarised and went down the drain.. since then i also use gladwrap instead of the screw lid as i found mold under the seal of that brew
And amazingly its so much easier
Its easier to clean
Easier to see if the yeasties have taken off and
I find im not opening the wort to air as much as i can just peer in

Although if you had infection of Brett last year you'd know what the onset of the taste and smell is
Still just let it ferment out and see what its like when you rack off to secondary

Tom

 

[flattop]

I did find another solution, i had about 8 litres left in a cube and a spare fermenter with a warped lid so i pitched in Saf 06 yeast and sealed in glad wrap, i will be able to sample that in 2-3 days and see what gives. Worst case both brews get infected, best case both brews are fine and i get an extra 8 litres from that brew day. If the full brew is Brett infected at least i can recover the 8 litre brew and still say i had an ok outcome. Oh forgot to mention in my earlier posts my SG was about 1032 i expected a little more but i never did the calcs on it and had too much water.....

If it is Brett i will be disappointed as i spent a lot of time trying to get rid of it last year. One thing that has made me not tip the whole brew is that the back flavor is relatively weak so either it is not Brett or it is only just starting up. I will be sampling over the next week to decide if i tip it out or not.
One thing about Brett is i made bread on the same day as my AG, which i also did last time i caught Brett maybe there's somehow a link.

Thirsty i now know you are right about the initial boil off value, i guess i used the BIAB instructions to literally and didn't take into account the fact that lid on boil would stop the evaporation. That's why i am aiming for a 25-28 litre brew next time.

Anyhow guys thanks for your replies i was beginning to get a bid disheartened.... I don't want to waste time on another infection....