exBEERiment | Hop Stand Temperature: 150°F/66°C vs. 200°F/93°C In An American IPA

Author: Martin Keen

While offering consumers an option with a bit higher strength and flavor, American IPA is most known for packing a hoppy punch, which brewers achieve through the use of myriad techniques. One such method is referred to as the hop stand, which involves adding a hefty charge of hops to wort once the boil step is complete then allowing it to steep for a bit before transferring to the fermenter. When employing a hop stand, modern brewers often consider the temperature of the wort, as it’s widely believed to have a substantial impact on the ultimate hop character of the finished beer.

Hops are made up several terpenes that contribute unique characteristics to beer, and each one has a fairly limited temperature window at which it volatilizes. This is important, as the presence of these terpenes is precisely what brewers rely on to impart pungent aroma to beer. For example, whereas the spicy, woody, and earthy caryophyllene has an approximate boiling temperature of 505˚F/262˚C, the classic citrus and piney notes of myrcene volatilize around 331˚F/166˚C. Moreover, isomerization of alpha acids is positively correlated with temperature, meaning additions made to cooler wort result in less isomerization. As such, many brewers of hop-forward styles intentionally pre-chill their wort before making the final post-boil kettle addition as a way to increase hop character while keeping the bitterness restrained.

I enjoy hoppy IPA and have made many batches over the years, often tossing in heaps of hops at various points during the brewing process. Like many, I started off by making “whirlpool” or “flameout” additions immediately after cutting the heat, when the wort was still close to boiling temperature, though after learning that some of my favorite commercial breweries were chilling the wort to specific temperatures first, I began experimenting with that technique. Curious of the impact this hop stand method was actually having on my beer, I designed an xBmt to test it out!

| PURPOSE |

To evaluate the differences between an American IPA that received a 20 minute hop stand at 150°F/66°C and one that received the same addition at 200°F/93°C.

| METHODS |

I went with a simple American IPA recipe for this xBmt in hopes any impact of the variable would be easily perceived by tasters.

Shoulders Of Giants

After collecting identical volumes of water for each 5 gallon/19 liter batch, adjusting them to the same desired profile, and heating them up, I incorporated the milled grain and set the controllers to maintain my desired mash temperature.

When the 60 minute mash rests were complete, I removed the grains and boiled the worts for 60 minutes with hops added at the times listed in the recipe.

Once the boils were complete, I rapidly chilled one wort to 150°F/66°C while the other was chilled to 200°F/93°C, at which point I threw the same amount of the same hop varieties into each wort then turned the pumps on to gently whirlpool during the hop stand.

After 20 minutes, I finished chilling both worts before taking refractometer readings showing a slight difference in OG.

At this point, I transferred identical volumes of wort to separate fermenters and pitched a fresh pouch of Imperial Yeast A15 Independence into each one.

The filled fermenters were connected to my glycol system set to 68°F/20°C. Given the variable in question, I decided to skip dry hopping and let them ferment for 2 weeks before transferring to CO2 purged serving kegs that were placed on gas in my keezer, where they were allowed to condition for a week before the beers were ready to serve.

| RESULTS |

A total of 29 people of varying levels of experience participated in this xBmt. Each participant was served 2 samples of the beer where the hop stand occurred at 150°F/66°C and 1 sample of the beer where the hop stand occurred at 200°F/93°C in different colored opaque cups then asked to identify the unique sample. While 15 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, just 13 did (p=0.13), indicating participants in this xBmt were unable to reliably distinguish an American IPA that received a 20 minute hop stand at 150°F/66°C from one that received the same addition at 200°F/93°C.

My Impressions: Out of the 5 semi-blind triangle tests I attempted, I correctly identified the odd-beer-out every time based purely on aroma. To me, cool hop stand beer had a slightly fresher hop aroma, while I perceived the warm hop stand beer as having a mild vegetal note. While the difference wasn’t terribly vast, I did have a preference for the beer where the hop stand occurred at 150˚F/66˚C.

Clawhammer Supply Impressions: I thought it would be fun to get some additional data on these beers and sent samples to our friends from Clawhammer Supply who were aware of the variable being tested. Kyle was confident in his selection based solely on aroma, and he did choose the odd-beer-out; however, Emmet and Libby chose one of the two identical samples.

| DISCUSSION |

IPA is one of the more costly styles of beer to brew due to the large amount of hops they require to achieve their quintessential character. As such, brewers have come up with various ways to extract as many oils out of the hops as possible, one of which is the hop stand where hops are added to the wort after the boil step is complete. With the understanding that many hop terpenes volatilize at temperatures around boiling, many brewers have adopted the practice of chilling the wort prior to making their hop stand additions. Interesting, tasters in this xBmt were unable to reliably distinguish an American IPA that received a 20 minute hop stand at 150°F/66°C from one that received the same addition at 200°F/93°C.

The volatilization temperatures for the various terpenes found in hops is well established, which makes results this difficult to explain, as the 50˚F/27˚C difference in wort temperature at the point of the hop stand additions is vast enough to have been expected to have a perceptible impact. While it’s fair to assume actual terpene levels between the beers were different, it’s possible that difference simply wasn’t enough to be easily perceived, and that both beers possessed some amount of the same terpenes.

This was one of those odd times where my semi-blind triangle test performance did not align with the blind tasters, as I could tell these beers apart based on aroma alone. However, it’s not like the difference was crazy, these beers were far more similar than they were different, but I did feel the batch where the hop stand occurred at 150˚F/66˚C had a slightly fresher hop character that I happened to prefer. Despite the non-significant results of this xBmt, my personal experience being what it was, I’ll likely continue chilling my wort a bit before making hop stand additions.

If you have any thoughts about this xBmt, please do not hesitate to share in the comments section below!

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