Dear Mr. Wizard,
I’ve been doing all-grain brewing for about a year now and noticed considerable more break material in the kettle than when I was brewing with extracts. I cool with an immersion chiller and siphon directly from the kettle to the fermenter, just as I had before, stopping the siphon before drawing any break material. My all-grain batch size has been coming in typically 0.5–1 gallon (1.9–3.8 L) shy of my target volume. Then I realized, that I’m leaving that “missing wort” in the kettle mixed with the break! My question is, what’s the best way to obtain the most wort from the kettle without a lot of break?
Mr. Wizard replies:This is really a straight-forward and easily addressed problem if you simply add a few more minutes and one additional step to your brew day — namely whirlpooling. And I’m not suggesting that you run out to the spa for a dip in a hot tub! The whirlpool method is used in nearly all commercial breweries these days to separate trub and often times pellet hops from wort in an effort to minimize wort loss. Typical wort losses in a whirlpool are less than 5% or less than 1 quart (~1 L) in a 5-gallon (19–L) batch.
Hot wort is usually whirlpooled by pumping wort out of the kettle and into a whirlpool vessel tangentially near the bottom third of the vessel. Some kettles are designed so that the kettle also serves as the whirlpool vessel (a pump and tangential inlet are installed for this purpose and the pump is later used for pumping to the wort chiller). This causes the wort to spin while trub and hop pellets collect in the center of the whirlpool. Most brewers wait for the wort to stop spinning before removing the wort from the whirlpool, either from a valve installed on the perimeter of the tank or by simply racking the wort with a racking cane.
In your case you are using an immersion chiller and these things disturb the wort currents that make the whirlpool method effective. There is nothing wrong with chilling the wort and then spinning it simply by stirring the wort with a spoon, allowing the rotation to stop and then racking to your fermenter. Since cool wort won’t kill bacteria or wild yeast, you need to be careful with the cool wort in an effort to minimize the risk of contamination. The spoon used to stir should be sanitized before use and the kettle should be covered while you wait for the wort to stop spinning.
This is an easy method and you will know if you are stirring fast enough by the way the trub settles in the center of the kettle. Commercial brewers shoot for an inlet velocity to the whirlpool of about 5 feet per second to get the desired result. If a trub pile does not form in the center of the kettle, try stirring a little faster to get the wort moving and smoothly remove the spoon while stirring so that it does not impede movement. Good luck!