[Pawtucket Patriot]

If I'm using pils malt, I'll go 90 minutes to drive off the DMS. I also use a 75 minute boil with non-pils grain bills as well, just so that I have 15 minutes to get the hot break before I add any hops, reducing the risk of boil-over.

+1

If pils is 50% or more of my base malt, I'll boil for 90 minutes to alleviate DMS concerns. Otherwise, I boil for 70 minutes (10-minute hot-break period).

[Will's Swill]

Yes, you need to remove enough water for the temperature to get hot enough for the sugars to caramelize.  We never reach that point with wort.  For example, maltose doesn't caramelize until over 350F.  Glucose around 320F.  Wort - 212F.  Your wort might hit 215F though Fred.

<edit>I found this cool boiling point calculator.  Enter the brix, it tells you the bp.
http://www.sugartech.co.za/bpe/index.php

Do you not get carmelization at the bottom of the pot?  I would think the bottom would get much warmer than boiling, but not sure how much more...

[tschmidlin]

Yes, you need to remove enough water for the temperature to get hot enough for the sugars to caramelize.  We never reach that point with wort.  For example, maltose doesn't caramelize until over 350F.  Glucose around 320F.  Wort - 212F.  Your wort might hit 215F though Fred.

<edit>I found this cool boiling point calculator.  Enter the brix, it tells you the bp.
http://www.sugartech.co.za/bpe/index.php

Do you not get carmelization at the bottom of the pot?  I would think the bottom would get much warmer than boiling, but not sure how much more...

Maybe.   The pressure won't be sufficient to cause the temperature rise, and it's the sugar that has to be hot enough, not the kettle.  I don't the physics well enough to know for sure.

[Will's Swill]

What would happen to fermentability if it did carmelize?  I was recently trying to brew a very small batch to do some mash experiments, and while I used a very low boil, I nevertheless reduced the wort to sludge.  It didn't look or smell burned, but the gravity was off the scale of both my hydrometer and refractometer.  Perhaps I actually made extract.    So I diluted it back to a reasonable gravity and pitched.  But no fermentation.  If I thoroughly carmelized the wort, would that remove the fermentables?

[tschmidlin]

What would happen to fermentability if it did carmelize?  I was recently trying to brew a very small batch to do some mash experiments, and while I used a very low boil, I nevertheless reduced the wort to sludge.  It didn't look or smell burned, but the gravity was off the scale of both my hydrometer and refractometer.  Perhaps I actually made extract.    So I diluted it back to a reasonable gravity and pitched.  But no fermentation.  If I thoroughly carmelized the wort, would that remove the fermentables?

Fermentability goes down as the sugars caramelize.  I really can't say for sure what you did though.

[sharg54]

Ninety minutes produces about the maximum isomerization potential for alpha acids in wort according to work by Malawicki and Shellhammer.  Beyond that time, the isomerized alpha acids are broken down to a slight degree and the bittering actually decreases.  In terms of energy efficiency of converting alpha acids to iso-alpha acids, a boil time in the 60 minute range is better than 90 minutes. 

Longer boils tend to darken the wort and there are maillard reactions taking place producing more melanoidins that enhance the maltiness of the wort. Not to mention increased hop isomerization or enhanced hop bitterness. The longer boil also concentrates these flavors that are created during the boil. Driving off DMS is probably one of the biggest reasons to boil longer but these other attributes also come into play as well.

Ok this is a bit over my head so if this don't come out right what can I say. So can I assume if I employ a longer boil of 90 minuets to bring out the flavors of the malt and don't start adding the hops until the last 60 minuets of the boil I can have the best of both worlds?

[tschmidlin]

Yes, you can boil as long as you like.  Some historical brews have even boiled overnight.  But if you boil the hops too long you can get a veggie taste, so save them for the last 60-90 minutes.  I don't go over that length, but have never tested it.

[bluesman]

Ninety minutes produces about the maximum isomerization potential for alpha acids in wort according to work by Malawicki and Shellhammer.  Beyond that time, the isomerized alpha acids are broken down to a slight degree and the bittering actually decreases.  In terms of energy efficiency of converting alpha acids to iso-alpha acids, a boil time in the 60 minute range is better than 90 minutes. 

Longer boils tend to darken the wort and there are maillard reactions taking place producing more melanoidins that enhance the maltiness of the wort. Not to mention increased hop isomerization or enhanced hop bitterness. The longer boil also concentrates these flavors that are created during the boil. Driving off DMS is probably one of the biggest reasons to boil longer but these other attributes also come into play as well.

Ok this is a bit over my head so if this don't come out right what can I say. So can I assume if I employ a longer boil of 90 minuets to bring out the flavors of the malt and don't start adding the hops until the last 60 minuets of the boil I can have the best of both worlds?

Yes.

Longer boil = Maillard reactions = enhanced flavor (maltiness)

Follow a calculated hopping schedule to achieve desired bitterness, flavor and aroma.

[SpanishCastleAle]

I've heard/read the 'no caramelization' in the boil before and it all seems to make sense.  But then what is happening when we do a 'kettle caramelization' of the first runnings a la Strong Scotch Ale?  It definitely changes the flavor; a lot, and also changes the mouthfeel; a lot.  It kind of tastes like caramel.  So what happened?

blatz tasted my SSA in the Hurricane Blowoff.  That was just base malt and a little roasted barley for color.  All the 'caramel' flavor and a lot of the mouthfeel was from kettle 'caramelization'.

[hopfenundmalz]

Caramelization happens at elevated temps.  This only happens when you have boiled off most of the water.  It starts at 230F and must go higher for some of the larger sugar chains, > 300F.

So if you boil down first runnings in the kettle or a pan you can caramalize.  If you boil all the wort at ~212F, you don't caramelize.  Are there elevated temps at the metal-liquid interface that can cause small amounts of caramelization?  That I don't know.

[weithman5]

would you get some carmalization during a decoction ie if you basically fried the pulled part?  and are any of the sugars carmalized during kilning at high temperatures?

[bluesman]

would you get some carmalization during a decoction ie if you basically fried the pulled part?  and are any of the sugars carmalized during kilning at high temperatures?

I would love to test the kettle caramelization theory someday.

Can a decoction be thick enough to enable the caramelization mechanism to occur?  I believe it's possible but the grain may get scorched.  

I believe the decoction would have to be really thick almost to the point of a doughball to enable the sugars to caramelize.

[stlaleman]

  and are any of the sugars carmalized during kilning at high temperatures?

That is how crystal malts are made. Wet malt is heated before drying to create the caramel/toffee flavors.

[ccarlson]

would you get some carmalization during a decoction ie if you basically fried the pulled part?  and are any of the sugars carmalized during kilning at high temperatures?

I would love to test the kettle caramelization theory someday.

Can a decoction be thick enough to enable the caramelization mechanism to occur?  I believe it's possible but the grain may get scorched.  

I believe the decoction would have to be really thick almost to the point of a doughball to enable the sugars to caramelize.

IMO you carmelization with a thick decoction.

[bonjour]

  Are there elevated temps at the metal-liquid interface that can cause small amounts of caramelization?  That I don't know.

Without doubt there are elevated temps at the metal-liquid interface.  I have not been able to determine what these temps are/will be.  Without a doubt the liquid wort/water will be at boiling temp, approx. 212F, in the kettle.  Without doubt there is no caramelization there.  There are issues commercially  with removing heat with liquid from metal-liquid interfaces, and they have been in the news recently (the reactors in Japan).  Different application but some of the same thermodynamic issues.
Scientifically it has never been proven that caramelization occurs in beer production. If it does it occurs on a micro level, and as I said there is no proof that this occurs.