Dry Hopping Tips and Techniques

One way to dry hop!

Dry Hopping Overview

Dry hopping most likely originated in England where brewers would add hop plugs just before shipping out the casks of beer to their customers. The beer would arrive with wonderful hop aromas that the brewers just couldn't get from kettle hop additions.

Most hops are added during the boil to extract the alpha acids that account for the bittering that balances the malty sweetness of beer. These hop additions usually take place at the beginning of the boil.

For flavor and aroma, brewers add hops to the boil during the last 5-15 minutes to preserve as much of the volatile oils as possible. But even these late additions will lose a huge amount of these flavor and aroma compounds. That's where dry hopping plays a huge role in preserving the aromas of the fragile oils normally lost during the late boil.

Dry hops are added in the fermenter or in the keg, typically at the rate of 1/4 to 1/2 oz per gallon. They are allowed to soak and macerate in the beer for up to several weeks. The result, a huge burst of hop aroma that defines many of today's beer styles, especially American beer styles.

Which Hop Varieties to Use

Most dry hopping is done with hop varieties that have low to medium alpha acid levels, generally 6% or less. It really depends on the hop variety however, because there are several higher alpha acid hop varieties the make very good choices for dry hopping.

Often, these are the "dual purpose" hops. Look for this term in the description if you are considering using one of these higher alpha acid hops for flavor and aroma. Many homebrewers dry hop with Centennial and Chinook hops. I used Simcoe when dry hopping my Gnarly Barleywine and the results were spectacular. That beer won first place in it's category in the MCAB in 2008.

The majority of dry hopping is done with hops that are labeled as flavor and/or aroma hops. These hops have a higher percentage of the volatile aromatic oils needed for flavor and aroma. You just get more "bang for your buck" when using these hops with more aromatic oils and less AA. Varieties most often used are Cascade, Crystal, East Kent Golding, Fuggle, Saaz, Hallertau, Tettnanger, and Willamette.

You can mix and match varieties as well. American varieties that tend to mix well are the 4 "C's",Centennials, Columbus, Chinooks, and Cascades. While each brings its own character to the beer, they all have an overall "citrusy" character that mixes and combines well, especially in American Pale Ales and IPA's.

There are other American hop varieties that work well when combined, Willamette, U.S. Fuggle, Yakima Golding, and Mt. Hood. Newer varieties that work well together are Liberty and Mt. Hood, which can be used in both ales and lagers.

Continental hop varieties of Hallertauer (Hersbrucker, Mittelfrüh, and Tradition), Tettnang, Spalt, and Northern Brewer all combine well.

British hops that work well together include Fuggle, East Kent Golding, Target, Challenger, and Northdown. Any of these English varieties can be mixed and matched to produce any English ale, whether brown ales, bitters, or an ESB. Styrian Golding (a Fuggle of British ancestry grown in the Slovenian Republic) are also very complementary in ales with other English hops.

Whole Fresh Hops

Whole or Fresh Hops, Pellet Hops, or Plugs?

The decision on which type of hops to use is much the same as the decision on the type to use in the boil. The difference being the size of the opening, whether you want the hops to float or drop, whether you want to use a bag and the cleanup.

Many of us still use glass carboys to ferment our beer in. So, I think you can see the problem right away...the size of the opening. You will often find that it's easy to get the hops in, but a heck of a job getting them back out. Here are the characteristics of each type when used in a typical glass or PET carboy:

Whole or Fresh Hops-must be weighed. They go into the neck easily but are difficult to get out when used in a bag after they have absorbed beer, and they absorb a lot of beer. So much so that you have to account for the volume lost when formulating your recipe.

Fresh hops float on top of the fermenting beer and thus you may have to perform some kind of agitation to get more surface area in contact with your beer.

These are probably best when used with one of today's wide mouth fermenters, especially when you want to put them in a bag.

Wet Hopping vs Dry Hopping

The process of using fresh hops for "Dry Hopping" is called Wet Hopping. All of the principles still apply but you must account for the extra water in the "wet hops". Generally, fresh hops will weigh 4 to 6 times more than the same dry hops. So, when you weigh out your fresh hops to use, simply take your normal dry weights and multiply by say, 5, to split the difference.

As an example...if you normally add 1 oz of pellet hops to the secondary fermenter, you would now add 5 ounces of fresh hops. (This probably varies by location and variety, so experiment and adjust accordingly). Congrats, you are now "wet hopping".
Pellet Hops-must be weighed as well. They are the easiest to get into the neck of the carboy but once they hit the fermenting beer, they break apart immediately. This can and often does cause an explosion of foam when they are added to the primary due to the increased nucleation sites (probalby in the thousands) available for CO² to attach to and come out of solution.

Once they are in the carboy though, they tend to flocculate along with the yeast or when added early on in the primary, they tend to stick to the sides as part of the krausen.

They work well in bags but you must use a bag designed for pellet hop, one with super fine mesh. You also have to be aware that pellet hops swell when exposed to beer and the volume that went in will be at least double coming back out.
Plug Hops-don't have to be weighed. They conveniently come in 1/2 ounce plugs. They fit well in the carboy neck if cut into smaller pieces. Once they are in the fermenter, you should treat them just like whole hops because they will quickly break apart once they become wet.

Dry Hopping with Whole Hops

Primay or Secondary Fermenter?

There has always been some debate on whether you should dry hop in primary. For the most part, you shouldn't add anything with delicate flavors and aromas (such as some fruits or herbs) in the primary because they will often get "scrubbed" away during a vigorous fermentation.

Hops, however, don't fall into the category of "delicate flavor and aroma". Some find that there is not much of a loss of flavor and aroma, as there is a change in flavor and aroma. What happens at the chemical level during a fermentation to aromatic oils is not fully understood, but I don't think that oils can be carried off by CO². So what remains is the question of whether the flavors and aromas you get from dry hopping during primary fermentation are the flavors and aromas you were looking for. This is something you will have to decide for yourself and some experimentation is definitely in order.

For those who feel that too much aroma is lost during primary, adding dry hops during secondary is definitely the way to go. Most homebrewers do dry hop during secondary fermentation. Before dry hopping in the secondary, rack off the trub in the primary to remove as much yeast mass as possible. Here are some tips:

Try to keep your beer as cool as possible while dry hopping. In the low to mid 60's °F (16-20°C) is best.
Since we are now past the aerobic phase of fermentation, make sure to minimize the amount of oxidation to your beer. I like to put a layer of CO2 over the surface of my beers when doing any type of manipulation after the primary.
And dry hopping definitely falls under the "manipulation" definition. We are not trying to keep oxygen from the beer as much as we are trying to keep oxygen away from the hops, although minimizing oxygen ingress at any stage will be helpful in maintaining the freshest flavors in your homebrew.

We definitely don't want to oxidize the hop compounds here. Here are a few tips you can use to keep oxygen out of the equation:
      1. You can Vacuum seal the hops to remove as much air as possible     before adding them to the vessel.
      2. Or, you can soak the hops in sterile degassed water (degas by boiling for 15 minutes then crash cool before adding the hops), drain and then add the hops to the vessel.
      3. One last thing you can try would be to add your hops when the fermenting beer still has a few gravity points to go to final gravity. The active yeast will help absorb some of the oxygen introduced from adding the hops.

This is probably overkill but when you are trying to fine-tune a recipe for competition, even the small things can make a difference between a Best-of-show or not.
After you finish dry hopping in secondary, and just like you normally do before you rack from secondary to a serving keg, crash cool the vessel you are dry hopping in to between 32-36° F (0°-2°C) to drop the hop mass and get as clear of a beer as possible.
You will get better extraction if you can stir the beer (without adding oxygen) to keep the hops in contact with more of the beer in your vessel, especially if you are using hop plugs or whole or fresh hops.
To reduce the hop mass, you may want to use a hops bag, especially if you are dry-hopping with pellet hops or dry hopping in a keg.

Using a Hop Back

One final method of adding enhanced hop aroma to your finished beer is the hop back. It is not really considered dry hopping, but some feel that the flavor and aroma added by this method is not as "raw" as that obtained from dry hopping.

A hop back is a small vessel (such as Blichmann's HopRocket) which will hold between 2 and 3 ounces of whole hops (pellet hops are not recommended here). The hop back is placed after the boil kettle and before the chiller. Beer is normally gravity fed to the hop back and can be pumped to the chiller (with some adjustment of the flow).

The hot wort coming out of the kettle will extract more hop oils than you can get from dry hopping. The added benefit for many is the fact that the hops are sanitized by the hop wort and this eliminates the worry of contamination.

Some believe that the cooling of the wort immediately after it has run through the whole hops preserves as much of the hop oils as would be released from dry hopping in the fermenter. Some also believe that the resulting flavor is more refined, subtle and less "raw" in comparison to a beer that has been dry hopped.

Many commercial breweries use a variation of the hop back, including Sierra Nevada (theirs is called a Torpedo) and the beer they brew is the Torpedo Extra IPA.

Concerns:

Some people worry about contamination when adding un-sanitized hops to green beer. DON'T. That's why hops became such a popular bittering component in beer. They have always added antibacterial properties to beer and thus provide a very poor substrate for bacteria to grow on.

Others worry that adding pellet hops that have been compressed under great pressure will not add as much aroma oils as other methods. I believe that the jury is out on this concern and most people can't tell the difference between beers dry hopped with pellets and those dry hopped with the other methods.

Adding too much hops will cause the beer to taste grassy or oily. This can happen, but it normally happens when you dry hop for too long of a period and is not dependent on how much hops you use. Most brewers dry hop for less than two weeks so this is not normally an issue. But if you plan on adding hops to a keg that won't be consumed soon, you may want to add your hops in a bag so you can remove them in a timely manner.

Another issue with adding dry hops to a keg is that the hop material can and often does clog up the entire system. This is another good reason to add your dry hops in a bag when adding them to your kegs.

References: Information for this article was adapted from the Brew Your Own Magazine article by Donald Million entitled Dry Hopping: Techniques online date of August 26, 2003, the book Homebrewing: Volume 1 Beginner Basics to Creating Your Own Award-Winning Recipes, by Al Korzonas, the paper in Chem. Educator 2000 entitled Beer: An Ancient Yet Modern Biotechnology written by Charles Bamforth, Department of Food Science and Technology , UC Davis and for the dry hopping tips, Advanced Dry Hopping Author: Dave Green, Brew Your Own Magazine, Issue: December 2014, Brewing Better Beer: master lessons for advanced homebrewers written by Gordon Strong.

Recommended Articles:
Hops Reference Guide
Fermenting in a Keg