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 or Fresh Hops, Pellet Hops, or Plugs?
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:
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:
Using a Hop Back
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.
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.
Hops Reference Guide
Fermenting in a Keg
If you find this site helpful, please link to us!