Author: Matt Del Fiacco

Kettle hop additions are typically split into three categories– beginning of the boil for bitterness, halfway through for flavor, and end of the boil for aroma. A part of this arguably old school mentality is based on the fact that certain compounds in hops react differently based on time and heat. For example, the isomerization of alpha acids that leads to bitterness is widely accepted as requiring hops be in contact with boiling wort for a certain duration, during which volatile oils that impart desirable flavor and aroma are purportedly driven off, hence later kettle additions are made to preserve those delicate oils.

Brewers these days seem to be favoring later kettle hop additions while paying little mind to the “classic” approach when it comes to bittering, a trend influenced by the rise in popularity of hazy IPA, which is known to lack the more assertive bitterness of its west coast counterpart. While this can be achieved by using less hops early on in the boil, many brewers have begun reducing their total boil length and skipping the early bittering addition altogether, relying solely on late kettle hop additions.

I’ve always been a bit skeptical of the contributions that are placed around mid-boil additions and have tended to favor later kettle additions to impart more hop character. It wan’t until I read The New IPA: Scientific Guide To Hop Aroma and Flavor by Scott Janish that I began to wonder what I might be missing by leaving out those earlier hop additions. Curious to see for myself, I set out to challenge my own judgement!

| PURPOSE |

To evaluate the differences between beers bittered to the same IBU with the same hop with either 60 minutes or 30 minutes left in the boil.

| METHODS |

Wanting to make sure any impact of the variable was readily apparent, I went with a simple Blonde Ale that received a single hop addition for this xBmt.

Timing Is Everything

Recipe Details Batch Size Boil Time IBU SRM Est. OG Est. FG ABV 5 gal 60 min 23.9 IBUs 4.1 SRM 1.038 1.009 3.8 % Actuals 1.038 1.01 3.7 % Fermentables Name Amount % Pale Ale Malt (Muntons) 7.5 lbs 100 Hops Name Amount Time Use Form Alpha % Lemondrop 31 g 60 min Boil Pellet 5.5 Yeast Name Lab Attenuation Temperature Independence (A15) Imperial Yeast 74% 60°F - 72°F Download Download this recipe's BeerXML file

I made a couple starters of Imperial Yeast A15 Independence a couple days ahead of time.

Having collected and adjusted the brewing water the night before, I started my brew day by setting the controllers to warm each batch to strike temperature.

As the water was heating, I weighed out and milled the grain for each batch.

With the water properly heated, I added the grains, kicked the pumps on, then checked to make sure both hit my intended mash temperature.

Following each 60 minute mash rest, I removed the grain baskets and let the drain while the wort was heating to a boil.

While waiting for the wort to heat up, I weighed out the kettle hop additions, each amount determined by the predicted IBU based on the point in the boil at which they would be added.

Both worts were boiled for 60 minutes with one batch receiving the hop addition as soon as a boil was reached while the other was hit after the wort had boiled for 30 minutes.

With each boil complete, the wort was transferred through a plate chiller on their way to sanitized Anvil fermentation buckets.

Hydrometer measurements revealed both worts achieved the same OG.

The fermenters were placed in chambers controlled to my desired 65°F/18°C pitching temperature and allowed to finish chilling overnight, after which I pitched the yeast starters.

I noticed bubbling in the airlocks later that day. With no signs of activity after 8 days, I took hydrometer measurements showing both had reached the same FG.

I proceeded with racking the beers to kegs then placing them in my kegerator where they were burst carbonated and allowed to cold condition for a week before being served to participants.

| RESULTS |

A total of 22 people of varying levels of experience participated in this xBmt. Each participant was served 1 sample of the beer hopped with 60 minutes left in the boil and 2 samples of the beer hopped with 30 minutes left in the boil in different colored opaque cups then asked to identify the unique sample. A total of 12 tasters (p<0.05) would have had to identify the unique sample in order to reach statistical significance, which is precisely the number who made the accurate selection (p=0.033), indicating participants in this xBmt could reliably distinguish Blonde Ales bittered to the same IBU at either 60 or 30 minutes left in the boil.

The 12 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. A total of 4 tasters reported preferring the beer bittered at 60 minutes, another 5 said they liked the beer bittered at 30 minutes more, and 3 had no preference despite noticing a difference.

My Impressions: Having failed a similar experiment done by Basic Brewing Radio, I didn’t go into this xBmt with much confidence. However, out of 5 triangle test attempts, I chose the unique sample 4 times, which is pretty consistent. To me, the beer bittered at 60 minutes had a more restrained hop aroma with a more present crackery malt sweetness, while the 30 minute batch had subtle yet more noticeable lemon and pine notes. My preference was for that batch bittered at 30 minutes, as I enjoyed the lemony hop character.

| DISCUSSION |

The idea that hop additions made early in the boil are solely for bitterness while those made later impart flavor and aroma has been around for a long time, and there’s little question most brewers have been influenced by this rule of thumb. As anyone who has brewed a delicious Helles with a single early boil hop addition likely knows, some hop character does seem to come through along with the bitterness, though not as strong a later kettle additions. The fact tasters in this xBmt were able to tell apart beers hit with a bittering charge with either 60 or 30 minutes left in the boil when IBU is controlled suggests time of addition may have an impact.

However, it’s also possible the difference in the amount of hops used in each batch is responsible for tasters’ ability to tell them apart. Then again, the 60 minute addition beer only received 9 grams less, which really isn’t that much. Seeing as the goal was to control for IBU, using more hops for the 30 minute addition batch was arguably a function of the variable, and anyone employing such a method would conceivably increase the hop amount to make up for lower IBU.

In follow-up conversations with tasters who completed the survey, some noted making their decision based on aroma alone while others commented on differences in flavor profile. I agree with the former and felt the 30 minute addition beer had slightly more hop character overall, though I didn’t perceive much of a difference in regards to bitterness. Having brewed several successful Short & Shoddy beers where all of the bitterness came from hop additions made in the last 30 minutes of the boil, I was somewhat surprised with the findings of this xBmt. Overall, my thinking about kettle hop timing has certainly been influenced by these results, in fact I think I’ll go back and adapt some old recipes to include typical “flavor” additions, perhaps that’ll bring them into their own.

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

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