This week I take a closer look at whirlpool hopping techniques, hop stands, what whirlpool hops bring to a beer and how you can maximize your hop aroma and flavor using this technique.
The Whirlpool Hopping Technique
The term Whirlpool Hopping is named after the whirlpool stage in commercial brewing that takes place after the wort has been boiled, but before the wort is transferred to a fermenter. On many commercial systems after flame out (or steam off), hot wort is circulated rapidly in the kettle creating a rotational flow that allows solids including grain bits, hop particles, proteins and polyphenols to gather in a tight cone and settle to the bottom of the vessel.
Wort is pumped from the outer edge of the whirlpool through a chiller (or heat exchanger) to cool the wort and then into the fermenter. This allows the sediment, often called the hop cone or trub in the center of the boil vessel so it does not all make its way to the fermenter.
As brewers came to a better understanding about the volatility of hop oils as covered in this article and also this one, the idea of adding hops in the whirlpool stage where temperatures are below boiling came into fashion. The advantage of the whirlpool stage is that the wort is still hot enough to promote absorption of many aroma oils but not so hot that volatile aroma oils evaporate.
Whirlpooling at a Homebrew Level – The Hop Stand
Most homebrewers do not have a pump and extraction system set up to create a rotational whirlpool flow in their boiler. However many of us do use whirlpool hop additions by simply allowing the boiler to sit for a period of time after flame out, called a “Hop Stand.” We then add our whirlpool hops at an appropriate time and temperature to achieve the desired result. So for example we might add hops when the wort chills down to 80 or 90 C (175-194 F) and leave the hops for 20 minutes while the wort chills slightly before siphoning or pumping it through a chiller to the fermenter.
Those using an in-the-boiler chilling coil might leave the wort hot during their whirlpool addition and then chill at the end of the desired exposure time before transferring to a fermenter.
Whirlpool Considerations
Whirlpool hops also add some bitterness to the beer because hop alpha acids continue to isomerize at typical whirlpool temperatures. While this is not typically the purpose of adding whirlpool hops it can be a benefit if you are looking for a bit more bitterness in the beer. The decision of how hot your wort should be when whirlpooling as well as the total exposure time of hops in the whirlpool will drive bitterness added, though it also affects aroma as whirlpooling at lower temperatures can aid in retaining aromas oils.
There is no hard and fast rule with regards to how hot or how long to whirlpool hops. Higher temperatures clearly promote more bitterness, but higher temperatures also run the risk of volatilizing fragile aroma oils. Longer time periods can aid in getting more aroma oils into the wort, but there is typically no good reason to whirlpool for hours. I would say those focused on aroma oils will choose temperatures in the 60-70 C (140-158 F) range with exposure times of typically 20-40 minutes. There is usually little benefit to going longer than that.
Choice of hops for the whirlpool is important. Yakima Chief Hops famously did a study a few years back on survivable hop compounds and they showed that some hops did much better than others at surviving the whirlpool and fermentation process than others. Different hops transfer their aroma oils into the wort at different rates, and also the act of fermentation includes CO2 gas as a byproduct that can strip many aromatics. Since preserving aroma oils is the main goal of whirlpool hopping, you want your hop choice to be one from the “survivable” list. In particular popular hops like Ekuanot, Centennial, Talus, Idaho 7, Mosaic, Chinook, Citra and Simcoe preserved a high percentage of the aroma oils like Geraniol, Linalool, and many thiols. Other hops like Galena, Comet, Willamette, Cascade, Amarillo and Crystal did not survive as well from the whirlpool and are likely better candidates to use for dry hopping.
The use of alternative hop products in the whirlpool as well as hop waste is another major consideration. Unfortunately even pellet hops used either for whirlpool or dry hops leave a thick trub behind that ultimately results in beer loss. Concentrated hop pellets like Lupomax from Haas, Cryo Hops from Yakima and CGX hops from Crosby remove a lot of the vegetal matter but are designed to preserve the majority of the bittering and aroma oils. For even less waste you can use supercritical extracts either with alpha acid like Incognito or Dynaboost designed for whirlpool applications.
Finally some new hop extract products can directly add aroma oils either in dry hopping or in a finished beer, reducing waste substantially and negating the need for whirlpool hops. Popular names include Spectrum from Haas, Subzero Hop Kief from Freestyle Hops, Hyperboost from Yakima and Abstrax Quantim as well as Euphorics from Haas. These products cost more than regular hops but the reduction in waste and ease of use can compensate for it. I cover some of the most popular new products in my article here.
I hope you enjoyed this week’s article on whirlpool hopping. Thanks for joining me on the BeerSmith Home Brewing Blog. If you want to take the guesswork out of brewing, please try my BeerSmith recipe software from BeerSmith.com. Be sure to sign up for my newsletter or my podcast (also on itunes and youtube) for more great tips on homebrewing.
