Reason for different boil times, all grain vs. extract?

I notice that recipes in "Beer Captured" seem to consistently call for a longer wort boil for all-grain recipes vs. extract + grain recipes. Any idea why?

A typical recipe might say:
- steep specialty grains 30 minutes, sparge
- boil, remove from heat, add extract + bittering hops
- return to heat
- boil 45 minutes
- add flavoring hops, Irish Moss, etc
- boil 10-15 minutes

...so, about an hour boil after steeping


...and the all grain version says to boil the wort from the mashed grains for 90 minutes.

I read a number of recipes that are like this, and I am not confusing boil times with mash/steep times. Any thoughts as to the difference? I would think that once a wort is created, you basically do the same thing in either recipe.

Just curious.

There are chemicals in fresh wort that need to boil off. Also, certain proteins are present that will congeal and drop out (hot break). The process of making the extract has already removed both, so you only need enough time for the hops to convert.

david_42 said:

There are chemicals in fresh wort that need to boil off. Also, certain proteins are present that will congeal and drop out (hot break). The process of making the extract has already removed both, so you only need enough time for the hops to convert.

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I use mostly DME. It's for that reason you mentioned that I have tried that "late"brewing" technique. I've been boiling 1-2 lbs of Extra Light DME for 45 mins and then add the remaining DME with only 15 mins to go.

The beers have been a bit lighter than normal, but I'm still not sold on the technique 100%. I'm not quite sure why either. Logically it makes sense.

Lately I have taken to cutting back my boil times on lower grav. brews (1.035-1.045) to 45 minutes and have not noticed any difference in quality.
I've also cut back mash times to 45 minutes.

The problem with cutting back on boil times is that you have not gotten the proper amount of bitterness out of the hops.

I suppose if you used hop extract you could boil your wort for 15 mins and add it prior to bottling to add the bitterness.

Rookie said:

Lately I have taken to cutting back my boil times on lower grav. brews (1.035-1.045) to 45 minutes and have not noticed any difference in quality.
I've also cut back mash times to 45 minutes.

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Boil time also has an effect on yield at the end. If you collect 7 gallon of wort you'll need a longer boil time than if you have 6.5 gallon of wort.