why do we boil the wort

[mm707]

Hi,

New to AG and just wondering why we actually boil the wort and why does it need to boil for so long ?

Thanks

 

[RobWalker]

60 mins extracts hop bitterness and boils off DMS which causes buttery/sweetcorn flavour, unwanted in most styles. your 60 min additions will only add bitterness, sometimes a 90 min boil is used (or 3 hour simmers for some other styles) but anything above 60 will only add a little more bitterness whereas the difference between 45 and 60 minutes is quite big. that's also why your 10 minute additions won't extract much bitterness at all, but add a lot of aroma :thumb:

 

[wigwamheed]

Exactly this ^. Also it will effectively sanitize the wort, killing any bacteria in it. Also helps to coagulate proteins which could cause hazing. Mostly for the isomerization (think its the right word) of the acids into the bittering hops which aren't very soluble in water.

 

[graysalchemy]

The boil is also essential for sterilising the wort and to secure the hot break. This is the point at which unwanted proteins in the wort precipitate out of solution during the boil, but you then need kettle finings and chilling in order to get them all precipitate out. Without the boil you would get cloudier beer. :thumb:

 

[mm707]

many thanks :thumb:

 

[craigite]

All of the above :thumb: plus Long boils also caramelise sugars in the wort so changing the flavour.

 

[jonnymorris]

Plus it'll concentrate the wort... i.e. higher SG.

 

[joe1002]

Plus it smells nice :lol:

 

[mm707]

Plus it smells nice :lol:

ha ha , the thought of stinking out the neighbours does appeal :)

 

[Stihler]

That is a question that frequently shows up on the BJCP Exam.

The following is from the BJCP Study Guide (http://www.bjcp.org/docs/BJCP_Study_Guide.pdf):
Boiling wort is normally required for the following reasons:

1) Extracts, isomerizes and dissolves the hop alpha-acids

2) Stops enzymatic activity

3) Kills bacteria, fungi, and wild yeast

4) Coagulates undesired proteins and polyphenols in the hot break

5) Evaporates undesirable harsh hop oils, sulfur compounds [DMS precursors], ketones, and esters.

6) Promotes the formation of melanoidins and caramelizes some of the wort sugars (although this is not desirable in all styles)

7) Evaporates water vapor, condensing the wort to the proper volume and gravity (this is not a primary reason, it's a side effect of the process)

- Scott