In the first post of this series I discussed how American IPAs went through a period where hop aroma, flavor, and bitterness levels progressively increased, culminating in double and triple IPAs that boasted triple digit IBU levels. In recent years the most sought after American IPAs have slowly but surely become less bitter and more aromatic. That doesn’t mean brewers have scaled back on the hops, more than anything it represents a shift in the timing of when the hops are used. In today’s post several Central Ohio brewers share their thoughts on crafting juicy, aromatic IPAs, but before we get to that some background information is in order.
Hop Chemistry 101
Broadly speaking brewers use hops because they contribute compounds that fall into one of the following three categories:
Alpha Acids – These are medium size organic molecules that serve two primary functions. They give beer its characteristic bitter taste, which helps to balance the sweetness of the malts, while simultaneously acting as an antiseptic, inhibiting the growth of bacteria. Common alpha acids found in beer include humulone, cohumulone, and adhumulone.
Beta Acids – Similar to alpha acids but typically present in much lower quantities because they are less soluble in water. They function in many ways like alpha acids, but their bitterness is often described as being harsher than that of alpha acids. Examples of beta acids include lupulone, colupulone, and adlupulone.
Essential Oils – These molecules are primarily responsible for the aromas and flavors we associate with hops. They are more volatile (meaning they evaporate easily) than alpha and beta acids. Their volatility is the key to adding aroma, because you only smell molecules that escape the liquid phase and reach the receptors in your nose. There are far too many essential oils to cover here, but some of the most important include:
- Humulene – Gives spicy, herbal aromas most closely associated with European noble hops,
- Caryophyllene – Imparts spicy, earthy, woody aromas, also found in black pepper and cloves,
- Myrcene – Accounts for 50-70% of the essential oil content of many of the American hop varieties including Cascade, Amarillo and Simcoe. Also found in cannabis, thyme, and bay leaves, it delivers herbaceous aromas that serve as a reminder that hops and cannabis belong to the same family.
The ratio of these compounds varies from one hop variety to another. Bittering hops like Chinook and Magnum are high in alpha acids, while so-called finishing hops like Cascade and Saaz possess high levels of essential oils. Dual purpose hops like Citra and Simcoe are rich in both.
The hop variety is not the only thing of importance, the stage at which the hops are added is critical in determining the final ratio of alpha acids to essential oils. To maximize the concentration of alpha acids brewers add hops at the beginning of the boil. Over time the high temperatures cause the alpha acids to isomerize* into iso-alpha acids, which are more soluble in water thus increasing their concentration in the beer. To maximize the levels of essential oils brewers take the opposite approach, adding hops near the end of the boil, as the beer is cooling from the boil, or best of all after fermentation (dry hopping). If added too early in the boil many of the volatile oils will vaporize or degrade and be lost before fermentation even begins.
In short add hops early to maximize the concentrations of iso-alpha acids and add bitterness, add hops late to maximize the concentrations of essential oils and add aroma.
*In chemistry the term isomerization simply means a change in the way the atoms in the molecule are connected and/or a change in the shape of the molecule. Two molecules that are isomers of each other, like humulone and iso-humulone, contain the same atoms but they are connected differently.
A Point of Reference – Ruination IPA
To calibrate the makeup of a modern IPA we need a point of reference. What do the hop additions look like in one of the 100+ IBU hop bombs that were so popular 5-10 years ago? Let’s take a look at the hop schedule for one of my favorite beers from that era, Stone’s Ruination IPA.
Below is the hop schedule from a homebrew recipe for Ruination IPA that I found in Beer and Wine Journal. I’m assuming that the recipe is fairly authentic because it was contributed by Stone brewmaster Mitch Steele. I’ve scaled the hop additions up to a batch size of 30 gallons to be comparable to the 31 gallon barrel (bbl) recipes that brewers use.
- Add 1.3 lbs (21 oz) Magnum hops at the beginning of the 90 minute boil
- Add 0.6 lbs (9 oz) Centennial hops and 0.2 lbs (3 oz) Chinook at knockout (the very end of the boil) or in the whirlpool
- Dry hop for not more than 7 days with 1 lb (16 oz) Centennial hops
If we break the hop additions down into percentages 43% of the hop bill is added at the beginning of the boil, 24% at the knockout stage, and 33% at the dry hop stage. Keep that ratio in mind as you read the comments of Central Ohio brewers that follow.
Hop Additions in the Heart of Ohio
Having a point of calibration I was curious to find out how the hops are used in some of my favorite Central Ohio IPAs. I reached out to several brewers and asked if they could give us a peek behind the curtain without giving away too many trade secrets. Most were gracious enough to send me candid responses.
Not surprisingly the way hops are utilized depends on the type of IPA being brewed. The response of Jamie Feihel, head brewer at Land Grant Brewing, is enlightening. For their session IPA Greenskeeper, where the malts are pretty restrained, he forgoes bittering hop additions altogether, whereas for their flagship Stiff Arm IPA he opts for an approximate ratio of 1:3 between the bittering hops and the late addition hops. Still far short of the bittering additions found in Ruination IPA.
Jamie Feihel (Land Grant): For Greenskeeper all of the hop additions come in the last 20 minutes. This allows us to pick up some bitterness, but mostly flavor and aroma. In my opinion this allows the Greenskeeper to be ‘hoppy’ but not overly bitter, as there is a difference. For Stiff-Arm about 1/4 of the total hop bill is added near the beginning of the boil, and the final 3/4 added within the last 30 minutes. This will give Stiff-Arm more of a bitter punch than Greenskeeper but still allows it to maintain good hop flavor and aroma.
A 1:3 ratio between the bittering hops and late addition hops also shows up in the recipes of aromatic IPAs brewed at Ill Mannered and Actual Brewing.
Tom Ayers (Ill Mannered): We have several schedules depending on the beer and the profile we are going for, super aromatic, bold bitterness, smooth bitterness and how that might blend with each hop bill. Our very aromatic IPAs like Powell! Right in the Kisser and Bitter Ex are aggressively late hopped with about 75% of the hop weight going in the kettle at whirlpool or dry hop. The other 25% is in the bittering addition.
Fred Lee & Jonathan Carroll (Actual): Our IPA, Magnon, features a 75 minute boil. We start with Columbus hops at the beginning of the boil. They have a high alpha acid content (14-16%), and being based in Columbus they seem like the obvious choice. Nothing much happens for the next 55 minutes and then we start adding Eureka! and Lemondrop hops every minute for the last 20 minutes of the boil. We experimented with a homebuilt continual hopping apparatus, but we couldn’t control the ratio of the two hops the way we wanted. So we went the old school way with 20 separate manual hop additions to layer in a complex hop profile. The ratio of bittering hops to late addition hops is approximately 1:3.
Hoof Hearted brewmaster, Trevor Williams, was pretty succinct in his response to my question, but his answer leaves little doubt that among local breweries he is pushing the envelope in terms of late hop additions.
Trevor Williams (Hoof Hearted): At this point I’d say 99% of the hops aren’t added during the boil. A teensy bit before and a whole lot after.
First Wort Hopping
Next I asked each brewer what they thought about a technique called first wort hopping (FWH), which entails adding hops to the wort at the end of the mashing stage, when the wort is roughly 150-160 °F, before raising the temperature to boiling. First wort hopping gives more IBUs than bittering hops added at the beginning of the boil, which makes sense because they are exposed to the hot wort for a longer period of time. Paradoxically many professional and home brewers believe that FWH delivers a smoother perceived bitterness, for reasons that do not seem to be well understood. As you will see the opinions of local brewers on FWH span a broad spectrum.
Fred Lee & Jonathan Carroll (Actual): We use first wort hopping for all of our beers. Although it’s hard to pin down the science behind FWH, the chemical reactions that happen as the wort is heated to boiling somehow give a smoother bitterness than hops added at the beginning of the boil.
Jamie Feihel (Land Grant): We have first wort hopped a few beers. The stories go that you will pick up about an extra 10% IBU and more of a ‘late addition’ flavor from FWH. Unfortunately, we don’t have the space or man power right now to do proper tests on these different methods. Hopefully, that will change with our new pilot system.
Tom Ayers (Ill Mannered): We use first wort hopping in some of our beers. I believe that it can help to give a beer a well-rounded smooth hop bitterness. I think this is a big part of what makes Powell! Right In The Kisser and Hopracha such a drinkable IPAs.
Angelo Signorino (Barley’s): I first wort hopped when I brewed an IPA in 1998 at Bunky’s Brewing in Newark. When it closed in 2001 I brought that maneuver to Barley’s.
Sam Hickey (Smokehouse Brewing): First wort hops: eh, I do them for some of the recipes I inherited, but I don’t really see the point. I actually have done one beer with and without FWH. For the one beer I experimented with I found more flavor in the batch made without FWH. But, yeah go for it if you want to I guess.
Approaches to Dry Hopping
When it comes to adding aroma no weapon in the brewer’s arsenal is more powerful than dry hopping. For those not in the know, dry hopping refers to the practice of adding hops to the beer after it has finished primary fermentation (or in some cases during fermentation as we will see). It’s an old technique, in fact the original English IPAs were generously dry hopped to preserve them for the long sea voyage to India.
The dry hopping stage is all about extracting essential oils that add aroma and flavor. In the calculations brewers use to estimate IBUs it’s assumed that dry hopping doesn’t contribute any bitterness. The temperatures are too low to isomerize alpha acids into the more soluble iso-alpha acids. However, I recently read an article by Scott Janish suggesting that dry hopping can lead to the extraction of the oxidized form of alpha acids. Apparently these molecules, which are called humulinones, pack 2/3 the bitterness of iso-alpha acids and are soluble enough to be extracted during dry hopping. He goes onto brew a beer that should be 11 IBUs based on the quantity of hops added during the boil, but turns out to be 44 IBUs, with the extra 33 IBUs coming from the dry hopping. So the conventional assumptions about bitterness and dry hopping may be antiquated. Thanks to Tom Ayers for pointing this article out to me.
When it comes to dry hopping the length of time is an important criterion. If the contact time is too short not all of the desired essential oils are extracted. If it’s too long the beer pulls out too many oils and you start to introduce “vegetal” aroma and flavor. So I asked brewers not only for their general thoughts on dry hopping, but also about the length of time they dry hop.
Angelo Signorino (Barley’s): We dry hop for between 4-7 days. When we started dry hopping in 1993, we dry hopped for closer to two weeks. In order to keep up with production demands and in the interest of experimentation, we tried dry hopping for a week or less and I really liked the results. I perceived the aroma and flavor to be at least as prominent and maybe less vegetal.
Colin Vent (Seventh Son): We dry hop most everything we do here, even a few beers that wouldn’t traditionally be dry hopped see a small addition. As I understand it, there isn’t any proper IBU increase with a dry hop, but there is the potential to extract quite a bit of hop polyphenols during the dry hop addition that can add an additional perceived bitterness, although it’s not true isomerized alpha acids.
Jamie Feihel (Land Grant): The dry hop amounts differ between ¼ lb per bbl up to 2 lbs per bbl depending on the beer. One thing I am always cognizant of is making sure the majority of the dry hops do not remain in the fermenter for more than a week. This can be difficult with some beers, Gravity Wave in particular, which has three separate dry hop additions. Once each addition has been in the tank for the desired amount of time, we try to drop most of the hops before the next addition is added.
Tom Ayers (Ill Mannered): This depends on the beer and the hop variety. Some as short as three days others as long as seven days or so. We learn what we like through experimentation and are still adjusting as we play with new hops and new beers.
Sam Hickey (Smokehouse Brewing): Dry Hopping varies depending upon the beer. For our imperial IPA, IBU UBME, I dry hop twice. This allows for the hops to really shine through with aromatics. Generally speaking dry hopping runs for 6-9 days.
Fred Lee & Jonathan Carroll (Actual): Dry hopping is an essential step in brewing any IPA. We typically dry hop for 7-10 days.
Standard brewing technique dictates that dry hopping occurs after primary fermentation is complete. This approach is not followed by purveyors of the über hazy, highly popular New England style IPAs like Trillium, Tree House, Tired Hands, and our very own Hoof Hearted. Dry hopping during active fermentation changes the taste, aroma and appearance of the beer in a surprisingly dramatic fashion. It seems to disrupt flocculation of the yeast, presumably by coating the surface of the yeast cells in way that prevents them from agglomerating and falling to the bottom of the fermentation vessel. Hence they stay in suspension and the result is a very hazy beer that is somewhat divisive among consumers and brewers alike. To get some perspective on this approach I asked Hoof Hearted brewmaster Trevor Williams for his thoughts on dry hopping.
Trevor Williams (Hoof Hearted): We are more aggressive in our dry hopping schedule than most breweries. Dry hopping starts before fermentation is complete and is repeated after it’s done. The haziness of many of our beers seems to come largely from starting the dry hopping before fermentation is complete. For example we use London Ale yeast in beers like Konkey Dong and Everybody Want’s Some. That’s normally a very flocculent yeast, but something about adding hops while primary fermentation is still going on confuses the yeast and makes it difficult to crash out. They aren’t the prettiest beers, but we’ll take a hit on the looks to get the delicious fruity flavors and aromas that come from the synergy between the hops and the yeast.
When I asked Fred Lee about dry hopping during primary fermentation he was less effusive.
Fred Lee (Actual): Dry hopping during primary fermentation is like throwing money away. Aroma hops aren’t cheap and the levels of CO2 that are produced when fermentation is active carry away some of the essential oils that you are trying to get into the beer.
Fred may have a point but there is no denying that Hoof Hearted’s IPAs are like no others being made in Ohio. What is it about the aggressive dry hopping schedule that changes the aroma and flavor of the beer? Is the difference due to the presence of suspended yeast/hop matter in the finished beer? Does exposure to high levels of CO2 preferentially carry away some oils and leave others behind, changing the aroma/flavor profile? Maybe being coated with hops stresses the yeast in such a way that they produce more fruity esters. I’m not sure anyone knows the answers to these questions. I certainly don’t and if Trevor knows he’s not saying.
Well that’s it for today’s post. Come back on Monday for the third and final post in this series when we talk about how brewers are using some of the new varieties of hops, and how certain combinations of hop varieties work synergistically to make the whole greater than the sum of the parts.