Hops main source of flavor and aroma are their oils. More specifically, it is the essential oils that provide the key non-bitter tastes and aromas that hops have. During the boil these volatile compounds evaporate, which is why aroma his are added as close to the end of the boil as possible.
Along with the idea of aroma hops being very late additions to the boil comes dry hopping. This is done primarily for aroma, as there is no boil for the essential oils to evaporate. Dry hopping is primarily done to add aroma and is completed by adding hops to the fermentation vessel directly.
There are three major essential oils in hops. Let’s check them out.
The major essential oils we are talking about here are:
These comprise about 60-80% of the oil in most varieties of hops. Th percentages and composition of oils in hops can vary dramatically from one year to the next, even within the same variety. Let’s take a look at these three major essential oils and see what each does.
Myrcene is a natural organic compound that is classified as a hydrocarbon. It is an essential of of many plants, including bay, wild thyme, parsley, and most importantly, hops. A few other plants that include Myrcene are:
- Lemon grass
All three essential oils listed here are very volatile in air, which means they disperse themselves easily into air. This is what happens when you smell the aroma of anything, especially beer. You are smelling the volatile compounds breaking down. For this reason, Myrcene is actually used in the perfume industry to help as an intermediary in perfume aromas.
This essential oil, which is named after the scientific name for hops, Humulus lupulus, is an isomer of Caryophyllene, and both are often found in a mixture in nature, as they are in hops. Humulene is one of they key parts of hops that give the “hoppy” aroma that so many beer that we love have.
Humulene has been found to possess anti-inflammatory properties. This means it is being studied as a treatment for inflammatory diseases. Just another way that beer, and more specifically hops, can actually help people!
Caryophyllene is a part of many aromatic plants, including cloves, cannabis, rosemary, and of course hops. This is also one of the oils that help to give black pepper it’s spiciness. Much like Humulene, this compound has been seen to reduce inflammation in the lab.
Studies into anti-cancer medicines have been done on Caryophyllene as well. This compound is very promising for the future of cancer and inflammatory medicine. And you thought beer was just for fun!
Caryophyllene is used as a food additive fairly often, giving a strong dry wood, pepper, and earthy flavor. It gives an herbal character to foods it is in, especially in beer. The aroma of Caryophyllene is obvious when you crush a fresh hop between your hands and smell it. If you were to do this, you would notice a spicy, earthy aroma that can even be somewhat sweet. This compound along with Humulene give beer that nice “hoppy” aroma we all love.
Much like Myrcene, Caryophyllene is used quite frequently in the perfume industry to aid in aroma dispersion. Found in foods ranging from ice cream to baked goods, to beverages, this is definitely a work horse of an essential oil!
There are many more essential oils found in hops, around 250 in total. About 22 of these are known to give aroma or flavor, and the three listed above are the key oils. As you can see, these are the reasons we add hops late in the boil and why we dry hop.
I hope this was informative and help you to understand your brewing more. Knowing this information should help you know the WHY behind following a recipe. Knowing why you do the steps you are doing makes brewing a much easier process, since you know what is going on and how to fix issues you may have when you taste the finished product.
Until next time,