Drying hopping is a brewing technique that some breweries brag about. But rarely are details provided describing the dry hopping process, and its affect on beer.
Normally, hops are added when the wort (beer) is boiling. The heat from the boil extracts bitter oils from the hops, making the beer bitter. However, boiling causes the more aromatic qualities of the hops to evaporate. To add more hop aroma to the beer, hops are boiled for a shorter period of time (from 1 to 5 minutes). However, the heat from the boil still causes some of the hop aroma to evaporate.
To add the most possible aroma, hops are added to the beer after it is done fermenting. Since there is no heat, none of the aromatic qualities of the hops are lost. The hops sit in the beer for 3 to 14 days (or longer), and their aromas seep into the beer. None of the bitterness of the hops is added to the beer because there is no heat to extract the bitter oils. Dry hopping does not increase bitterness, it only adds aroma.
Dry hopping is very common in beers that want to highlight the taste and aroma of hops, namely India Pale Ales and American Pale Ales. Drying hopping can add very strong smells of grapefruit, pine, flowers, spice, citrus or herbs depending on the type of hop being added to the beer.
How to Dry Hop Your Beer
1. Decide if you want to dry hop your beer: Not all beer styles should be dry hopped. While I completely encourage going crazy with experimentation, sometimes the aroma of the malt or yeast might clash with the aroma of the hops. Dry hopping an IPA is a good place to start, because you can’t really go wrong. Some might argue an IPA must be dry hopped to be considered a good IPA.
2. What hops are you going to use: This very must depends on what aroma you are going for. American hops like Cascade, Columbus and Centennial will add a strong citrus aroma to your beer. English hops like East Kent Golding or Fuggle will add an earthy herbal characteristic. Noble (German) hops like Saaz, Mt. Hood or Crystal will add floral and spicy aromas. Smell the hops to determine which aroma you prefer. You can always combine different types of hops to create a wide spectrum of aromas in your beer. I generally like a blend of a citrusy hop like Cascade with a more floral hops like Crystal to create a sweet and fruity aroma with a bit of spice.
Also, don’t mess with hop pellets for dry hopping. Only use whole hops. They are the most aromatic. If you’re going to dry hop, do it right. Kick those hop pellets to the curb.
Be aware that the AA% of the hops does not matter because dry hopping does not add bitterness.
3. Quantity of hops: More hops means more aroma. For a 23 litre/6 gallon batch of beer, 1-2 ounces of hops is generally enough to get a nice aroma. If you want a more subtle aroma to compliment other aspects of the beer, add an ounce or less. If you want to tear people’s nostrils a new one, go all the way up to 4 ounces. I normally add 1 ounce of Crystal and 1 ounce of Cascade to my IPAs.
Be aware, hops absorb some of the beer, so the more hops you add, the less beer you will have at the time of bottling.
4. When to dry hop: Dry hopping should occur after primary fermentation. If you add the hops during the primary fermentation, the carbon dioxide from fermentation will carry away most of the aroma, resulting in an un-aromatic beer. Here’s a schedule I generally follow for dry hopping:
7 days in the primary fermentation tank
7 days in the secondary tank without hops
7 days in the secondary tank with hops
Total of 21 days fermenting, with 7 days dry hopping
I only dry hop for 7 days because hops can give off grassy flavours if they sit in the beer too long (though I have let hops sit in beer for 3 weeks and I generally haven’t noticed any bad flavours). Furthermore, I haven’t really noticed any benefits of letting hops sit in the beer for any longer than 7 days; most of the aroma seems to be extracted within 7 days of adding the hops. People who use kegs instead of bottles often add the hops directly to the keg instead of the secondary tank. This is very convenient. Jamming 3 ounces of hops through the narrow opening of carboy (secondary tank), however, is not very convenient. Perhaps I should invest the money into kegging.
5. Bottling: When transferring the beer from the secondary tank into the bottles, the hops will still be sitting in the beer. This means it is possible to have hop seeds and hop leaves end up in your bottles. This adds a certain natural quality to the beer, but tends to freak out big wusses. You can use a hop bag to avoid having hops just floating around carefree in your beer. Hop bags can be used both during the boil and dry hopping.
Hop aroma does decrease with time, so don’t age your dry hopped beer too much.