Whirlpooling vs. Flameout (Knockout)

Question

I'm new to adding different hop additions after the boil. I'm not sure of the difference between recipes that cite add hops (whirlpool) and add hops (flameout). What's the difference? With flameout it seems I would simply add the hops after the boil, let it sit for 30 min or so, then chill. Is whirlpool the same, or do you actually add hops and create a whirlpool effect? And, if so, how do you actually create the whirlpool and for how long?

As an aside, with only 4 brews under my belt (2 all-grain, 2 partial extract), this seems to raise a red flag over the post boiled wort being exposed to the air. All of the books and articles I've read stress to chill the wort as fast as possible to pitch before any airborne bacteria can get into your wort. Sometimes it seems different brewing techniques contradict one another.

Answer 1

These two hop addition timings are quite similar. Your guess about flameout is mostly correct, adding the hops right after you turn off the heat.

Whirlpool refers specifically to a strategy to transfer wort into a fermentation vessel that is meant to leave behind most of the trub. BYO has a more detailed description of how it works for professionals and homebrewers. In short, stirring the wort in one direction quickly, and allowing the wort to settle before transfering will leave a significant amount of the solids behind. Whirlpool would be to add the hops just before beginning to create the whirlpool.

Your instincts about wanting to chill the wort quickly are correct. In addition to avoiding contamination, when adding hopes at either of these timings it is not expected for the hops to steep for long. They are meant to extract delicate oils and flavors from the hops that can destoryed by high heat and/or overpowered by other hops flavors.