Kathy Folio from North Central Distributing forwarded me an email newsletter from Merchant du Vin, Importer of such wonderfull brews as Samual Smiths, Ayinger, Rochefort, and Westmalle among others. The newsletter contained this wonderful article on hops. Of course, many beer geeks may already know this stuff, but I think this article will be very informative for someone learning the ins and outs of beer. So enjoy.

Beer starts as water and grain - barley, usually - but almost every beer is seasoned with a traditional spice: hops, the flower of a fast-growing perennial vine. This wonderful, bitter seasoning balances the deep richness of malt flavors, and also adds aroma and flavor notes that can range from elusive to outrageous.   Hops were included in Pliny the Elder's "Natural History" encyclopedia of the first century AD, and they have been cultivated for 1000 years, with the first records coming from Bavaria's Hallertau region.

The part of the hop vine that brewers use is the flower of the female plant.  This flower, which looks like a small, soft green pine cone, has an aromatically herbal aroma and a bitter flavor.  Brewers add some hops as their kettle comes to a boil, because the bitter component of the hops is  not very water-soluble: it takes time in the boil for the bitterness to get into the liquid. Because the boil drives off some of the nice herbal aroma, brewers who want that aroma in the beer add more hops close to the end of the boil: those hops aren't in long enough to add much bitterness, but the aroma isn't boiled away.

Hops added early are called "bittering" or "kettle" hops, and those added close to the end of the boil are called "finishing" hops, or sometimes "aroma" hops if they are added right at the end.  Dry hopping?  That's adding hops to the finished (fermented) beer, either in a keg or in a conditioning tank just before bottling.  Dry-hopping provides freshest hop aroma, and doesn't add bitterness.

While there are many many varieties of hops, they all can be analyzed two ways:

First, how much bitterness does a specific hop variety provide?  Bitterness in beer comes from the "kettle" hops, and it is one of the "basic flavors" that our tongue can sense. The bitterness of a hop variety can be measured as a percentage of alpha acids by weight and can range from 2% all the way up to near 20%.  To increase bitterness in beer, brewers can use more hops, or use a "higher-alpha" hop, or boil the hops longer.  The final bitterness level is a number: International Bittering Units, or IBUs.  For reference, a yeast-forward beer style or a light American lager may have 10-12 IBUs; many craft beers and imports range around 25-45 IBUs; and some styles - particularly from American craft brewers - can surpass 70, 90, or even more IBUs.  It is important to note that a super-bitter beer is usually backed up with lots of malt and alcohol flavors for balance.  A super-roasty imperial stout at 9% abv and 90 IBUs may taste less bitter than a medium-bodied India Pale Ale with 65 IBUs.

The second way to analyze hops applies mainly to hops used for finishing: beer tasters use wonderfully subjective adjectives like "citrusy, earthy, noble, spicy, barnyardy, zippy, musty, grapefruity, fresh, herbal, or piney," and the list goes on.