Imperial IPA is one of the most popular styles among craft beer enthusiasts today. An unapologetic celebration of hop bitterness, flavor, and aroma, Imperial IPA showcases all that Humulus lupulus has to offer and induces what Russian River Brewmaster Vinnie Cilurzo terms a “Lupulin Threshold Shift.” But brewing such a big, bold beer at home can challenge even the most dedicated homebrewer. Imperial IPA is bitter, but your brew day shouldn’t be. By attending to a few key matters, the glorious elixir of the hops plant can be yours.
Don’t complicate matters
Many of the highest-rated Imperial IPAs are light in body and easy to drink, with a crisp, clean finish. To achieve this effect with your homebrew, design your recipe with the bulk of the grist either basic pale malt or 2-row malt and use specialty malts sparingly. It’s probably best to avoid dark crystal, Munich, and other highly kilned or roasted malts that can detract from the hops and make your beer taste flabby and overly sweet. If you’re looking for a little more roast flavor, either stick with a small quantity of light crystal malt (less than 5 percent of the malt bill), or choose a flavorful base malt such as Maris Otter. Extract brewers should use an extra light extract and add flavor with a small amount of crystal malt steeped in the brewing liquor.
One of the pitfalls that many homebrewers encounter when brewing their first Imperial IPAs is actually making them too alcoholic. Ethanol accentuates body and sweetness, which can distract from the hops you’ve so lovingly packed into your masterpiece. To let the hops really shine, consider keeping it under 10 percent ABV.
Many homebrewers struggle with attenuation when making high gravity beers, but full attenuation is critical for Imperial IPA. The final gravity should be in the neighborhood of 1.010 to 1.016 so that the finished product goes down easily.
Take it from John Fiorilli, director of brewing operations at the Mountain Sun Pub & Brewery in Boulder, Colorado, whose Hop Vivant Imperial IPA won Hopunion’s 2009 Alpha King Challenge. “Under-attenuated Imperial IPAs detract from the hops bitterness and overall hops presence in the finished beer,” says Fiorilli. “They give the impression of sweetness instead of maltiness, but maltiness is different from attenuation.”
All-grain brewers can encourage full attenuation by mashing like you’d barbecue—low and slow. A 90-minute mash at 150°–152°F (65°–67°C) will produce nicely fermentable wort that has enough body to support truckloads of hops.
And all-grain and extract brewers alike should consider including simple sugars such as dextrose in the malt formulation. Dextrose is 100 percent fermentable and will both lighten the body and help your yeast ferment to a lower terminal gravity than it might with comparable all-malt wort.
Speaking of yeast, you need lots of healthy cells to get the job done for a high-octane brew like Imperial IPA. Use brewing software or an online calculator to compute the pitch rate, and do your best to fully oxygenate the wort. Use a diffusion stone with pure oxygen if you can, or aerate the wort with a sanitized whisk. (The handles of many inexpensive whisks fit comfortably into the business end of a power drill.)
Hop like you mean it
If ever there is an appropriate time and place for the phrase, “Go big or go home,” this is it. Imperial IPA features huge, aggressive American hops flavor, so don’t be afraid to push the limits. As long as you aim for an original gravity north of 1.070, you’ll have plenty of flexibility with your choices of hops.
You can use any hops you wish, but classic varieties couple high levels of alpha acids with citrusy, resinous flavor and aroma. The usual suspects include Amarillo, the “C hops” (Cascade, Centennial, Chinook, and Columbus), Simcoe, and Warrior. But newer varieties like Citra, Galaxy, Mosaic, Meridian, and Nelson Sauvin are also finding their way into Imperial IPAs and can offer the unique complexity of tropical fruit and spice.
A 90-minute boil helps extract the most from your bittering charge, while large late kettle additions of high-alpha varieties will contribute both bitterness and flavor. The only quantitative goal is achieving enough IBUs to balance the malt, so aim for a bitterness ratio (theoretical IBUs divided by gravity points) of 2.5 or higher. Beyond that, you have a great deal of flexibility in choosing the amount and timing of flavor and aroma hops.
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But, of course, it’s not an Imperial IPA without dry hops. Russian River uses a double dry-hop regimen in their Pliny the Elder, which took Gold at the 2005 and 2006 Great American Beer Festivals. About two weeks before packaging, Pliny gets hit with dry hops and then gets a second dose with about five or six days to go. Cilurzo’s Pliny the Younger is taken even further and features an incredible four dry-hop additions.
Mountain Sun’s John Fiorilli agrees with the multiple dry-hop approach. “Many brewers are using smaller but more frequent dry-hop additions (e.g., two or three small doses every three to five days instead of one large addition). The theory is that it takes only a few days to infuse the aromatic oils into the beer, but after several days the beer may be exposed to some undesirable hops compounds.”
When you employ such a large quantity of hops, you’ll lose quite a bit of liquid to absorption. Many homebrewers consider this the fee they pay for hops flavor, while others adjust their recipes to account for the loss. The volume you lose will depend on your particular recipe and brew system, but it’s not unheard of for hops to steal one gallon of a 5-gallon batch. Some homebrew stores sell pure hops extract for bittering, which can help reduce the quantity of vegetal material left in the fermentor.
As with all big beers, fermentation can quickly get away from you if it gets too warm. The optimum temperature depends on your chosen yeast, but most American ale strains should do well in the 64°–68°F (18°–20°C) range. If you don’t have a temperature-controlled environment, choose the coolest spot you can find and try not to let the temperature exceed the upper 60s. Slowly raising the temperature to around 70°F (21°C) toward the end of fermentation can encourage full attenuation. Using a blow-off tube is frequently a necessity for Imperial IPAs.
Freshness above all else
Ultimately, the most critical piece of the puzzle for optimum hops flavor is freshness. Much like a French reduction that concentrates the flavors and aromas of the original sauce, Imperial IPA focuses malt and hops into a single, powerful experience. Only use hops that have been kept cold in vacuum-sealed or nitrogen-flushed packaging for maximum effect.
When it comes to drinking your Imperial IPA, another challenge may rear its head. While it may be tempting to lay down a few bottles for later, resist this urge. Hops don’t age well, and unlike imperial stout or barleywine, Imperial IPA won’t get better with time.
“For me, this is one of the trickiest decisions when brewing and serving Imperial IPAs,” notes Fiorilli. “Due to the alcoholic strength, these beers need some aging time to mellow out the 8–10 percent ABV. However, hops character always tends to fade during extended aging processes, so we strike a delicate balance between giving it enough aging time and serving it while hops aromas are still assertive.”
So enjoy your Imperial IPAs young and often. And before long, you can experience that transcendental Lupulin Threshold Shift for yourself.