Boiling
After mashing, the beer wort is boiled with hops (and other flavourings if used) in a large tank known as a "copper" or brew kettle - though historically the mash vessel was used and is still in some small breweries. The boiling process is where chemical and technical reactions take place, including sterilization of the wort to remove unwanted bacteria, releasing of hop flavours, bitterness and aroma compounds through isomerization, stopping of enzymatic processes, precipitation of proteins, and concentration of the wort. Finally, the vapours produced during the boil volatilise off-flavours, including dimethyl sulfide precursors. The boil is conducted so that it is even and intense - a continuous "rolling boil". The boil on average lasts between 45 and 90 minutes, depending on its intensity, the hop addition schedule, and volume of water the brewer expects to evaporate.
At the end of the boil, the hopped wort settles to clarify in a vessel called a "whirlpool", where the more solid particles in the wort are separated out.
Read more about this topic: Brewing
Famous quotes containing the word boiling:
“Most people hew the battlements of life from compromise, erecting their impregnable keeps from judicious submissions, fabricating their philosophical drawbacks from emotional retractions and scalding marauders in the boiling oil of sour grapes.”
—Zelda Fitzgerald (1900–1948)
“‘Twas like a Maelstrom, with a notch,
That nearer, every Day,
Kept narrowing its boiling Wheel”
—Emily Dickinson (1830–1886)
“Unmeasured power, incredible passion, enormous craft: no thought
apparent but burns darkly
Smothered with its own smoke in the human brain-vault: no thought
outside; a certain measure in phenomena:
The fountains of the boiling stars, the flowers on the foreland, the
ever-returning roses of dawn.”
—Robinson Jeffers (1887–1962)