exBEERiment | Dry Hop Duration: 12 Hours vs. 7 Days In An American IPA

Author: Steve Thanos

Back in the 18^th century, British brewers learned they could prolong the freshness of beer shipped overseas by tossing in some hops, which had the secondary effect of contributing increased hop aroma and flavor. As modern brewers developed more effective methods for beer preservation, many continued to rely on dry hopping, a term that purportedly stemmed from the fact the hops added post-fermentation hadn’t been boiled and hence were “dry.”

Perhaps due to the longer shipping times of the day, it became accepted practice to leave the beer in contact with dry hops for an extended period, typically around a week or so. However, more recently, some evidence has suggested a reduced dry hop duration leads to a more desirable hop expression in the finished beer with less vegetal notes, which has been backed up by several anecdotal reports. Indeed, IPA expert and professional brewer, Scott Janish, recommends dry hopping for between 1 to 3 days, noting that some compounds are fully extracted after just 24 hours.

I’ve brewed a lot of IPA over the years and started off allowing the dry hops to mingle with the beer for a week or longer, the guiding presumption being that extraction of oils is positively correlated with time. Considering some of the information that has come to light over the last few years about this widely used method, I was curious how vastly different dry hop durations would compare and designed an xBmt to test it out.

| PURPOSE |

To evaluate the differences between an American IPA that was dry hopped for 12 hours and one that was dry hopped for 7 days.

| METHODS |

For this xBmt, I went with my house IPA recipe, which strays a bit from popular West Coast IPA due to the inclusion of crystal malt. My own true version of Midwest IPA that I unabashedly endorse!

Normalize Midwest IPA

After collecting 2 sets of water and lighting the flame to get them heating up, I weighed out and milled the grains.

Once the water for each batch was adequately heated, I incorporated the grains then checked to make sure both were at the same target mash temperature.

While the mashes were resting, I prepared the kettle hop additions.

Once each 60 minute mash was complete, I removed the grains then boiled the worts for 60 minutes before chilling them and taking refractometer readings showed both worts achieved the same target OG

The filled carboys were placed in my chamber and left to finish chilling to my desired fermentation temperature of 68°F/20°C for a few hours before I pitched a pouch of Imperial Yeast A01 House into each.

After a week of fermentation, I added the dry hop charge to one batch while leaving the other untouched for 6 days, at which point I added the same amount of dry hops to it. The following morning, precisely 12 hours later, I transferred both beers to CO2 purged kegs then took hydrometer measurements showing the beer dry hopped for 7 days finished 0.003 SG points lower than the 12 hour dry hop beer.

The filled kegs were placed on gas in my keezer and left to condition for a week before they were ready to serve.

| RESULTS |

A total of 25 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of the beer dry hopped for 12 hours and 2 samples of the beer dry hopped for 7 days in different colored opaque cups then asked to identify the unique sample. While 13 tasters (p<0.05) would have had to accurately identify the unique sample in order to reach statistical significance, 15 did (p=0.006), indicating participants in this xBmt were able to reliably distinguish an American IPA dry hopped for a 12 hour duration from one dry hopped for 7 days.

The 15 participants who made the accurate selection on the triangle test were instructed to complete a brief preference survey comparing only the beers that were different. Just 2 tasters reported preferring the 12 hour dry hop beer, 12 said they liked the beer dry hopped for 7 days more, and 1 had no preference despite noticing a difference.

My Impressions: Out of the 5 semi-blind triangle tests I attempted, I correctly identified the odd-beer-out 4 times. To my senses, the beer dry hopped for 12 hours had quite a bit less hop aroma and flavor than one dry hopped for 7 days, which I highly preferred.

| DISCUSSION |

Dry hopping is a popular method used by brewers to impart beer with desirable hop characteristics, and while it was traditionally believed that a longer dry hop duration yields more oil extraction, many modern brewers have found success with reducing the time dry hops are in contact with beer. Corroboratively, tasters in this xBmt were able to reliably distinguish an American IPA dry hopped for 12 hours from one dry hopped for 7 days.

The results of this xBmt support the idea that dry hop duration has a perceptible impact on beer, and based on the subjective ratings of tasters who accurately identified the unique sample in the triangle test, one might presume extended dry hopping leads to a more preferable outcome. However, it’s possible 12 hours simply wasn’t long enough for adequate extraction of hop compounds to occur, and hence that beer didn’t pack the punch of the beer dry hopped longer.

Over the last few years, I’ve settled on dry hopping for between 4-5 days, and while I preferred the beer dry hopped for 7 days to the one dry hopped for 12 hours, I’ll be sticking to my typical practice, as I feel it yields excellent results. Given my own assessment of these beers, if ever I’m in a pinch for time when making a batch of IPA, I’ll make sure to dry hop for at least 24 hours, as I felt the 12 hour dry hop duration resulted in muted hop characteristics.

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

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