Looking for basic explanation of longer boils

[dr0506]

Hey All,

Just a very general question as to why some beers are boiled for 90 or even 120 minutes as opposed to 60.
Is it to only develop a more complex hop flavor or does it correlate to having a higher OG? Or is the reason something totally different?

 

[Yellowirenut]

I am not sure I have seen hop additions longer that 60 min.
But many brewers boil the wort for 90 or 120 then add the bittering hops when they have 60 min left. I have been told longer wort boils can produce deeper malt flavors and also raise the OG as you are boiling off more water. - not sure if it is true.

 

[titansvol]

The main reason for a 90 minute boil is to drive off DMS precursors. This is not necessary for extract brewing.

 

[dr0506]

So is DMS dependent on the type of grains used then? I have boiled a few dubbels for 90 minutes for that exact reason, but does that process continue in a 120 minute boil?

 

[MXDXD]

Drive DMS, get a better hops isomerisation, kettle caramelization and longer boil due to more sparging due to high OG brew.

 

[titansvol]

https://www.homebrewtalk.com/extend-the-boil.html

Here is a good article on extended boils.

 

[rhys333]

Caramelizafion for sure, if the recipe calls for it. Regular two-row based beers typicalls require only 60 minutes to drive off DMS, but a pilsner base may need 90 minutes or more.