Dip hopping further explained
Q: (QUESTION 1): Your video about dip hopping (available at www.byo.com/video/dip-hopping) is intriguing and has piqued my interest. When making the slurry, what ratio of water-to-hops is recommended? This seems like an important detail. And the other curious thing to me is the information on 2M3MB. What are the parameters on the chart? the comparison and reduction of 2M3MB clearly shows on the chart but what is the actual difference, quantitatively? Is it significant?
— Warren Wilson • via email
(QUESTION 2): After reading the “Techniques” column “Dip Hopping: Maximize the Best Hop Aromas” by Drew Beechum and Denny Conn in the November-December 2024 issue and doing a bit of research, it looks like I should be boiling the wort for a short time before transferring the dip hop portion out. Why would this need to be done as opposed to just transferring and reserving it directly from the kettle before it even reaches a boil?
— Chris Campbell • Bordentown, New Jersey
A. It’s not often that we receive two questions related to the same topic at roughly the same time. Seems that the stars are aligned, and inquisitive brewers are again interested in our recent discussions about dip hopping. So, I am lumping my answer to these two questions together.
For those readers new to this topic, dip hopping was developed by Kirin Brewing in 2012 and reportedly reduces the concentration of unpleasant aromas associated with 2-mercapto 3-methyl butanol (2M3MB), an onion-like aroma that develops during fermentation, and myrcene from dry hopping, while simultaneously preserving linalool and other pleasant hoppy aromas from dry hopping.
The dip hop method originally described by Kirin uses an agitated tank to mix hop pellets with water, followed by the injection of this slurry into the cool wort stream as wort is cooled en route to the fermenter.1
OK, so the first question related to dip hopping comes to us from Warren Wilson who saw this topic discussed on the BYO+ video series. Warren, unfortunately I am not able to find any specifics about the slurry concentration used to hydrate the hop pellets. Based on Kirin’s data showing the change in wort gravity in three different trials (no dip hops, dip hops prepared in ambient water, and dip hops prepared in 203 °F/95 °C water), it appears that the water used for hop hydration was essentially part of the wort recipe because all trials began at the same wort gravity.
Dip hopping is believed to work its “magic” by adding nucleation sites to wort prior to fermentation. These nucleation sites reduce dissolved carbon dioxide in fermenting beer, increase peak cell density by easing growth inhibition related to dissolved carbon dioxide, shorten fermentation time, and reduce the concentrations of 2M3MB and myrcene (dip hop versus dry hop). In my opinion, slurry concentration is not critical. In fact, some American craft brewers have used a variant of dip hopping where hop pellets are simply added to an empty fermenter prior to filling with wort. Because many commercial breweries do not have an easy way of adding hop pellets to fermentation tanks, it’s likely that Kirin adapted their dip hopping method to existing equipment in the brewery.
Your next question, Warren, is a very good catch. The data related to 2M3MB concentration during fermentation shown on the poster presented by Tsuchiya, Ota, Yoshimoto, Kobayashi and Inadome at the 2018 Brewers Summit is missing the scale on the y-axis.1 They do show that the units for 2M3MB concentration are µg/L, which sheds a bit of useful light. The aroma threshold for 2M3MB is reportedly 0.17 µg/L. It appears that the 2M3MB concentration is 0 µg/L before fermentation and rises to 4 “ticks” in the dip hopped trial and 8 “ticks” after 7 days of fermentation. Making assumptions about the scale is frustrating. However, if one “tick” is greater than 0.1 µg/L, the concentration of 2M3MB in both the dip hopped and control trials were above threshold at the end of fermentation. It is also clear that the concentration of 2M3MB in the dip hopped trial was about half that of the control. This difference in concentration explains why the dip hopped beers are described as having a more desirable aroma.
The Kirin study also measured the concentration of H2S (hydrogen sulfide), or rotten egg aroma, in the control and dip hop trials, where the dip hop trial contained about 9 ppb of H2S versus 14 ppb of H2S in the control. The aroma threshold of H2S in beer is about 10 ppb.
On to the second question from Chris Campbell, relating to a variation on dip hopping described by Drew Beechum and Denny Conn in their recent column. In their article, they call for removing a portion of wort after the boil begins for use in their spin on dip hopping. After the wort is removed, the remainder of the wort is boiled as usual and the wort with the dip hops is later reunited in the fermenter. Boiling the wort before use is just good brewing practice to kill off bacteria that are almost always present in wort — an exception to this rule is in very long mashes used to produce historical, no-boil beers where the long and hot mash effectively pasteurizes the mash.
I’m a big fan of dip hopping for two main reasons. The first is that it offers some improvements to beer aroma without having to invest in new equipment, a new hop product, or find an obscure hop variety. The second reason is that the data supporting how the method works are clear and pass the sniff test. Not to throw shade on other brewing methods, but there are several that don’t hold up well under scrutiny. Three cheers to dip hopping. Dip, hop, hooray! Dip, hop, hooray! Dip, hop, hooray!
