Hops provide the balance to the sweetness given by the malt. They give beer bitterness – yes bitterness. Remember the mega brewery's ad campaign of “Don’t drink bitter beer”? Well even their beers have hops in them – very little. Bitterness can be a wonderful flavor. In fact, the craft brew scene has become overwhelmed with bitter and overly bitter beers, and people love it! Of all the beer in the US, only 8% by volume is “craft beer”. Yet, over 60% of the aromatic hop varieties on the marker are utilized by these brewers. [40% of all hops grown are the aromatic type] They use a lot of hops and we cannot get enough. Every year the IBUs (International Bittering Units) are pushed higher and higher and we say, “is that all you got?”
Hops come from a flower of a bine not a vine. There are over a hundred varieties and counting. They are categorized by aroma, bittering or dual purpose (both). Most U.S. hops are grown in Washington, Idaho, or Oregon. The flavors and aromas of these hops are quite varied: floral, resinous, grassy, various kinds of citrus, passion fruit, pineapple, piney, etc. and any combination of those.
Noble hops are primarily from Europe. They are low in bitterness and alpha acids but very fragrant. They include:, Hallertauer, Spalter, Saaz, and Tettnanger. There flavor and aroma profiles are: spicy, floral, herbal and fruity.
Hops are primarily used in the boil and fermenter, but rarely in the mash. There are 3 profiles that hops can give to beer. The first is bitterness. Hops that are added to the beginning of the boil and remain there for the 60 or 90 minutes add bitterness. The alpha acids in the hop oils have to isomerize (become soluble) in order go into the wort. It takes at least 30 minutes of a boil for this to significantly happen. The alpha acid’s molecules break down and are better absorbed into the wort. These hops lose their flavor but contribute bitterness due to the long boil.
The second profile that hops give is flavor. To bring out the flavor, hops need to be added and boiled between 10 and 30 minutes with the peak being around. 15- 20 minutes. This is where we get the varietal flavor. When you hear people talk about citrus, passion fruit, pine, and resin etc., this is the part of the boil that provides those flavors. If hops are added at the 20 minute point then decided that you have to boil longer, then these flavor profiles will start to fade. This is especially true for the third profile of hops – aroma.
Hop aroma dominates in the last 10 minutes of the boil. The peak is thought to be 1-5 minutes. These are the most delicate oils in the hop flower. They are so delicate that the hoppiest of beers lose some of their aroma in seconds! If you ever get a chance to try Heady Topper by the Alchemist in Vermont, it says to drink right from the can because some of the aroma is lost if poured.
The way to add hop aroma to your brew is done in several ways. Hops can be added in the last 1-10 minutes of the boil which is the easiest way. They can be added at “flamout” (0 minutes), whirl pooled and left in the kettle with the lid on for 20 minutes, or dry hopped - the hops are added to the fermenter, usually in a nylon bag, once most of fermentation is done.
Dry hopping requires more attention to detail than the other methods. Because the hops are added to the fermenter, there is an increased chance of infection. However, it is slight. The pH has lowered and the alcohol has risen to a level that is difficult for bacteria to take hold. However, it is important that the hop bag be cleaned and sanitized first. As for the introduction of oxygen, it is not a problem provided fermentation is not 100% complete. The remaining yeast activity will scrub out the extra O2.
Hops and yeast do not get along well. The compounds in hops provide chemicals that do not favor bacterial or fungus. Since yeast is a fungus - you see the problem. When dry hopping, add the hops after the yeast has flocculated. This will help maximize the clearing of the beer.
There are 2 types of acids in hops: alpha and beta. We are mostly concerned with the alpha acids because they are predominant in fresh hops. The beta acids dominate after a long aging period – one to two years and have a different flavor profile usually found in sour beers.
Hops can be purchased in three forms: whole, plug, and pellet. Most homebrewer’s prefer the pellets. They are easier to handle, contain more alpha acids ounce per ounce, have a longer shelf life, and are a lot less messy. One drawback is that they can be hard to separate from the wort.
Hop plugs are more rare, but have very similar attributes to pellet hops
Whole hops are more of a purist ingredient. The hops have not been processed and are believed to have a slight flavor and aroma advantage over pellets. A slight adjustment up or down of the pellets can compensate for the difference. Whole leaf hops require 10% more by weight than pellets to provide the same bitterness, flavor, and aroma. There are, however, some techniques and equipment that can only be used with whole flowers such as a “hop back” or “hop rocket”. These devices act as a sort of filter when transferring wort from kettle to fermenter. The hot wort leaves the boil kettle and is funneled through this device, which is full of whole leaf hops, pulling hop aroma and some flavor away and into the wort. Pellet hops cannot be used with this device because they would clog it up.
So how do we know how many ounces of hops to use in our brew? Recipes are a good starting point, but they are adjusted for that brewer’s equipment. I find that software is the only way to go. There are many equations out there which you can learn. Personally, I would rather brew than worry about my numbers being right in an equation that may not consider my equipment or efficiencies.