Wort Darkening Throughout Boil?

[snoozer]

I brewed last weekend and made a german pils. I used Wyermann extra pale malt and noticed the beautiful pale colour during vorlauf. When boiling on my italian burner I got it going really hard and thought I'd better turn it down at one stage as too much was gonna evaporate. About 45mins into the 90 min boil my mate commented on how it was darker now (I hadn't really noticed) but he was right, I was hoping it was the hot break responsible for the colour but after the boil when it was cool it was crystal clear with shitloads of break underneath but the wort now was noticeably darker. Beersmith tells me my evaporation loss was 16%, so maybe I should turn the heat down next time. I did end up having to add a couple of litres of water to make up the final volume. But would the wort have darkened given a full volume (non diluted) wort? is it possible to boil a full volume wort so vigorously it actually darkens? I know it happens with extract boils where a concentrated wort is boiled, but AG wort?

 

[mika]

Melanoiden reactions and caremlisation of the wort, especially with a thin base pot, could lead to wort darkening. I've seen the same thing, but not consistently. Though it will always darken a bit compared to straight out of the tun.
I forget whether it's 8 or 12% evap rate required to drive off the precursors to DMS, but either way, 16% is going, but it's not ridculous. Reduce your evap rate, reduce how many litres of water you flush thru the grain bed, potentially reduce your efficiency..just as another consideration.

 

[Thirsty Boy]

Wort will always darken during the boil - it is absolutely unavoidable.

Given that, the vigor of your boil has a serious effect on darkening, and turning down the heat will help a lot, as will shortening the boil if you are currently boiling for longer than an hour. Basically more boil equals more colour, whether its more via higher intensity or more via length.

Matti is right - if you adjust you boil vigor so that somewhere between 8 & 15 % of your starting volume boils off during an hour - your boil is vigorous enough to do all the things it is supposed to do. Given that you are somewhere in that range, it is a matter of fine tuning so that you don't darken the wort more than you want.

Brewing is an unfortunately organic process - it takes a bit of art as well as a bit of science to get it right. Keep brewing and you will get there.

TB

 

[SJW]

After 80 All Grain brews with my Italian Spiral Burner and a HP reg I have only just relised the benefits of not boiling to the max and having the wort jumping out of the kettle. Evaporation losses went from 15 or 16% down to 10 or 12%, less (percieved) melanoidin formation and most of all more break material is retained in the trub due to the fact it is not being broken up by a over vigorous boil. As for wort darkening.........................I dont think (IMO) it makes any diff. Sure there might be some slight darkening as the volume reduces but this is minimal and I would argue that caremlisation really happends to any great extent at least when using a 50 litre s/s vessel, not unlike a keg see Mika's post.

Steve

 

[snoozer]

Thanks for your replies guys. So I think I'll try reducing the evap rate a few %, and maybe shorten the boil to 60 mins (for my pale beers at least). I always thought the more vigorous the boil, the better, too Steve but maybe only up to a point?
cheers :icon_cheers:

 

[SJW]

A rolling boil does not mean "jumping out of the pot". I have see many comm ercialkettles boiling in and they appear to only be just boiling with the bubbles coming up on one side of the kettle. Saves gas too.

 

[Fourstar]

A rolling boil does not mean "jumping out of the pot". I have see many comm ercialkettles boiling in and they appear to only be just boiling with the bubbles coming up on one side of the kettle. Saves gas too.

+1 for that

My 3 ring rambo and low pressure reg just gets 30L to the boil/rolling/simmer. Lid 1/2 on and shes almost jumping out of the kettle. The last beer I did (hefeweizen) and almost NO break material in my NC cube . a nice gentle boil but dropped my efficiency as i had a higher post boil volume 1.040 OG

will still be a great beer nonetheless. :chug:

 

[Kai]

On top of the chemical changes your wort is also darker because you've just removed almost 16% of the water from it. Sounds silly, but even that's enough to make a noticeable colour difference in a pale wort.

 

[Thirsty Boy]

+1 for that

My 3 ring rambo and low pressure reg just gets 30L to the boil/rolling/simmer. Lid 1/2 on and shes almost jumping out of the kettle. The last beer I did (hefeweizen) and almost NO break material in my NC cube . a nice gentle boil but dropped my efficiency as i had a higher post boil volume 1.040 OG

will still be a great beer nonetheless. :chug:

Fourstar - your efficiency wasn't changed because you ended up with a higher post boil volume - it was exactly the same, your beer was weaker, but you had more of it. The amount of sugar you created/extracted was still the same no matter what happened in your kettle.

I also blanch a little at the use of the word "gentle" with relation to a boil. I am a big believer that boils shouldn't be too hard... but gentle they also shouldn't be. There has to be a good exchange of wort from top to bottom and there needs to be bubble formation. The physical agitation of the wort has an effect on the chemistry, and a hell of a lot of the chemical changes in wort happen at the surface interface of the bubbles themselves. So there has to be a fairly high amount of both.

so I am uncomfortable with words like gentle & simmer - as I am uncomfortable with the picture of wort boiling so hard its trying to jump out of the pot. Happy, rolling boil medium is what makes me relax.

That and 13 beers at any rate...

TB

 

[MHB]

Although I dont recognise Weyermann extra pale malt among the list of Weyermann Pilsner Malts.

The attached PDF of Weyermann Pilsner shows two colour values, the extract or wort colour and the boiled wort colour, which could be up to 6 EBC, up to 4 EBC darker than the extract.

Milliard reactions always take place during the boil, the more vigorous and more concentrated the wort the more and faster darkening occurs.

As TB said boiling is a very, well varied and complex part of brewing.

One trick I have found that helps is to put the fire off centre under the kettle; this encourages good circulation of the wort at lower heat imputes.
You still get good hop utilisation but you can reduce the heat until you are getting 8-10% evaporation/hour and maintain good wort circulation.

MHB

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