Rapidly cooling wort from boiling down to room temperature or lower is no small task. But it's a very important one. A fast temperature drop is critical for several reasons:
- Risk of contamination: There are plenty of airborne yeasts and bacteria that would love to feast on your freshly boiled wort when it’s in the range of 80-160°F (27-71°C). You want to be in this zone as briefly as possible.
- Protein coagulation: A rapid cool-down knocks proteins out of suspension and results in clearer beer in your glass.
- More predictable hops utilization: Hops continue to contribute bitterness even at sub-boiling temperatures. Letting wort remain too hot for too long extracts additional bitterness you may not want.
The most popular ways to chill wort are ice baths and wort chillers. And of the latter, you have a few choices, all of them excellent.
Most of us start out using an ice bath, and it’s not a bad choice if you’re cooling down only three gallons or so for a small batch or concentrated boil. Simply fill a kitchen sink or bathtub with cold water, dump in as much ice as possible, and add the pot of hot wort.