One of the choices that a homebrewer must make is whether they choose to use fresh hops or hop pellets. Both approaches are effective for brewing beer, but they have some key differences that you should understand before using one or the other.
These are versions of hops that are highly processed. The processing means that the hops are more concentrated than fresh hops and all non-resinous material is removed. Hop pellets are frequently made from a blend of different hops, resulting in a specific level of alpha acid and a consistent outcome.
Hop pellets are by far the most common option and the most widely available hop product. Almost all professional brewing companies make use of hop pellets, which is an indication of their effectiveness and reliability. However, there are exceptions to this rule, and some brewing companies do make use of fresh hops instead, Sierra Nevada and Anchor being two of the most well known. I believe that Sierra Nevada uses whole cone in SOME beers, while Anchor uses them exclusively.
Whole Cone Hops
Whole cone hops do not have the level of processing that is found in hop pellets, and their composition means they have less surface area exposed to the wort. As a consequence, whole cone hops are not as efficient at delivering alpha acids, flavor, and aroma to your beer, and more have to be added to get the same outcome as you would from pellets.
However, because fresh hops do not go through as much processing, there is also the potential for more nutrients to be left in the hops. This can have an influence on the overall flavor of the beer used, both positive and negative. Some folks claim that they can taste the freshness of whole cone vs pellet hops in the beer (positive), but using too many to achieve a level of bitterness and aroma you want (in a double IPA for example) could result in grassy or vegetal flavors in your beer.
Wet Hops, Green Hops, Fresh Hops
This is the practice of using hops that have not been dried or processed. There's some debate on whether fresh hopped beers are any different from using any other form of hops. Detractors say that it's a gimmick that dupes the non-informed craft beer drinking into thinking the product is “fresher”, while others say they truly can taste a difference. Still, you can't deny that it's pretty fun to drink a beer that's just a little bit different from what you're used to, even if it's just placebo.
Dry hopping is when you put hops into the wort AFTER it's done boiling. This can be done during fermentation or in the secondary. Pellets, dried whole cone hops, and wet hops can all be used for dry hopping.
Years ago, hop extract was a bit “no-no” because of the chemical methylene chloride they used to extract oil from flowers. Recently however, they've begun to use CO2 to extract the oils, which has no negative flavor on the beer or possibility of chemical contamination. Personally, I've never used it, but according to Hop Tech, it's used for the aroma and flavor, not for bitterness. It's essentially dry hopping but faster and more predictable.
There are also isomerized hop extracts that can be used to add bitterness to your beer (during the boil). If you ever wondered why some hops are added for 60 minutes and some are added at flame-out, this is the reason. The 60 minute boiled hops are “bittering hops”. Most of their aroma and flavor boil off, but the continuous heat on the oils starts a process called “isomerization”. Beyond that it's a bit too sciency for me right now, but I'll update this post later after I've finished reading my For The Love of Hops book.
Choosing Which to Use
Hop pellets are by far simpler to use in the process of brewing, are easy to store and less is needed to reach the desired outcome. For many brewers, these are all the reasons needed to always use hop pellets. Many brewers also feel that whole cone are challenging to use as they soak up the word and clog up ports in equipment. For most commercial brewers, this all relates to the economics of brewing.
Both hop pellets and whole cone hops produce some residue and have the potential to clog up the system, and which one works better is often dependent on the specific system that the individual is using, rather than the inherent advantages and disadvantages in each of the types.
Hop pellets are relatively easy to store because of their small size, and they can be stored for between three and four years without any major issues. In contrast, whole cone hops will last up to a year if stored correctly, but may only last as little as six months. Chalk up another point for hop pellets.
From all my research it really seems that the main reason to use whole cone hops is nostalgia and tradition. Most homeberwers simply don't have access to regular and significant amounts of their favorite (or rare) hop varieties unless they are in pellet form. However, something I do see a lot is using whole cone hops for dry hopping. I don't know if this produces “fresher” hop aroma because the oils have not been processed, but it seems that even in this case, pellets win. The lupulin glands have been ruptured during processing, meaning more aroma can infuse with your beer, while it may take significantly longer with non-ruptured glands in whole cones.
At the end of the day, there are advantages and disadvantages and it is personal preference which is used. In some cases, a particular variety is only available in one of the two forms, which makes the decision making process much easier.
photo credit: duncan