Theoretical question here.
What happens when wort is boiled? Why do we do it? Why is the process not done at cooler temperatures?
- Maillard reactions, Melanoidin formation, possibly some caramelization
- Isomerization of hop acids
But I'm not confident that's the whole story. I know why #1 is important, I can guess at why #2 is important, and I assume #3 is important because all homebrewing instructions tell you to do it.
The genesis of my question is the discovery of this little beastie: http://www.williamswarn.com/
(I have no intention of buying one. It's just an item of curiosity.)
The kits they sell include LME (presumably pre-hopped) and DME, with dry yeast. The instructional video on the home page show the procedure as putting hot-but-not-boiling water in the machine and then adding the extract and the yeast right on top of it before closing the lid. No boiling of the malts at all. That generates the question: why is wort boiled?
One would presume that these extract kits are pasteurized, removing that part of the boil equation. Digging further in the web site reveals recommendations for doing partial mash; steeping specialty grains and hops (in separate pots) before adding to the machine. There's even a reference to all-grain brewing, assumedly a mash conducted before adding wort to the machine, which led me to the conclusion that the WilliamsWarn is not a brewing machine per se, but rather an automated fermenter with integrated carbonation and serving. But I digress.
So what is the difference in procedure between a normal homebrew process and this machine which allows them to get away without a boil? What purpose does the boil serve us?
Hard facts, assumptions, and wild speculation welcome.