EVAPORATION....WHAT'S IN IT?

[trucker5774]

When we boil our wort we leave the top of the boiler open and lose a fair volume to evaporation.

What is in the vapour that we don't want in the beer. I remember there is a reason..........I just can't remember what the reason is Could we part cover the boiler and have less evaporation?

[booldawg]

I believe the steam drives off unwanted tanins from the hops that would produce a harsh bitterness if allowed to drop back into the wort.

[vacant]

I believe the steam drives off unwanted tanins from the hops that would produce a harsh bitterness if allowed to drop back into the wort.

I wonder if that could be tested by sticking your finger under the lid half-covering the boiler and tasting the condensation? You might kill an urban myth.

[grumpysod]

You don't use a lid as you want to drive off DMS (Dimethyl sulphide) which can cause a cooked cabbage flavour in your beer.

[Capped]

It's only quite recently that I started brewing again after a long break. I boil with the lid totally removed,as per the general consensus of those on here who are more switched on than me! But years back,I kept the lid on but with a large bore (about 1- 1/2 inch) tube jammed in the lid then stuck out the window. It reduced evaporation considerably and there were no dripping-wet walls to contend with. But I have to say,I now realise that the quality was impaired.Grumpysod's 'cabbage' comment does strike a chord - not in every brew by any means,but it has happened.Never had anything like that with the lid removed. Leave it off!

[Minimasher]

I will 'look' out for the cooked cabbage. I boil on the stove with the lid on. The lid is vented so some steam does escape but I reckon (from a comparision with the lid off) I save about 80% evaporation.

If Dimethyl Sulphide is the nasty beast we are trying to rid ourselves of, then this is something to think about...

Wikipedia states that DMS boils at 37C, so I would imagine this is evaporated away through the vent without any danger of it condensing back into the boil - the lid will be well above 37C so I can't see it being able to condense back into the pan at all.

I'd really like to get to the bottom of this one myself because i am a stickler for saving both energy and water. Lid on makes a big difference to both!

Maybe an alternative (if DMS is our only problem?) is lid off for the first 5-10 minutes of the boil then lid on for the rest?

[adm]

I will 'look' out for the cooked cabbage. I boil on the stove with the lid on. The lid is vented so some steam does escape but I reckon (from a comparision with the lid off) I save about 80% evaporation.

If Dimethyl Sulphide is the nasty beast we are trying to rid ourselves of, then this is something to think about...

Wikipedia states that DMS boils at 37C, so I would imagine this is evaporated away through the vent without any danger of it condensing back into the boil - the lid will be well above 37C so I can't see it being able to condense back into the pan at all.

I'd really like to get to the bottom of this one myself because i am a stickler for saving both energy and water. Lid on makes a big difference to both!

Maybe an alternative (if DMS is our only problem?) is lid off for the first 5-10 minutes of the boil then lid on for the rest?

Why do you want to save water? Unless you are on a water meter, I can't see why - it's just going to turn to steam and end up back in the water eco cycle anyway and will only be a few litres.It's not like you're destroying it - just changing it's state for a short while. Different matter with the chiller water flow, and fair enough on the wish to save energy.

But there's probably a reason that breweries through the ages have had big chimneys coming off the coppers....and last time I brewed a stout in the kitchen, once the steam had cleared, there was all sorts of brown gunge left on the walls, so it's not just steam that's coming off the boiler....

[Minimasher]

We are on a water meter. Every little helps.

[adm]

We are on a water meter. Every little helps.

Yeah - fair enough then!

Personally, I think water meters are a crime (and you should dig yours up and bypass it) - especially in a country where it rains so bloody much and we pay heavy taxes. Personally, I think our tax money should be used to pay for basic public services like water, electricity and gas delivered direct to the user.....rather than selling the whole lot of to private sector companies who charge us more for the privilege of using what we've already paid for.

Come the revolution....

[Eadweard]

Wikipedia states that DMS boils at 37C, so I would imagine this is evaporated away through the vent without any danger of it condensing back into the boil - the lid will be well above 37C so I can't see it being able to condense back into the pan at all.

It's not just boiling off the DMS, you want to convert the DMS precursor SMM to DMS and then boil it off, or the SMM may convert to DMS during wort cooling or fermentation and give your beer that delightful vegetable flavour.

[Minimasher]

the SMM may convert to DMS

Good to know, but what is SMM?

I think water meters are a crime (and you should dig yours up and bypass it)

Would you believe we actually opted to get it put in? It costs us half the amount when compated to 'rates' even with a young child. I know where you are coming from regarding the revolution, but even if there was a revolution, the fact that 40% of the worlds population doesn't have access to enough suitable water to maintain even basic health/ hygiene standards makes think this precious natural resource may be a right, but it's also a privilege.

[mysterio]

S-methylmethionine, which is a DMS precurser. It is heat labile, so is degrated when malt is kilned - so Pale Ale malt usually is free of it.

I've had no problems with a 60 minute boil and UK lager malt, I do chill quite rapidly though.