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The hop plant, Humulus lupulus, has been known to humans since Roman times when, according to Michael Jackson, hops grew "wild among the willows, like a wolf among sheep." Their predatory nature, presumably, led to the name lupulus (from lupus, wolf in Latin). Throughout their history, hops have been used in various capacities, from the tanning of leather, to use as shampoo and, notably, as a sedative (hops are related to cannabis). Although hops were cultivated as early as the late eighth century, they weren't used in beer until the 12th. Prior to that time, brewers employed horehound, bark, mugwort, bog myrtle and nearly every other spice as bittering agents (to combat the cloying of the malt). In beer, hops impart three attributes: bitterness, flavor and aroma (apparently superior in these respects to bog myrtle). That hops are used to bitter beer is well-known, but their more subtle qualities of taste and aroma are less well understood. The flavors hops give range widely from peppery spiciness to a grapefruit citrus; the aromas from earthy to floral or cedary. To begin with, the bitterness. Hops contain a chemical known as alpha acid from which comes both bitterness and the preservative quality of hops. (The high hopping rates of India Pale Ales originally came from the intent of English brewers not to make especially bitter beer, but to ensure that it would remain fresh and well-preserved on the long journey to the subcontinent.) The chemical is present in greater or lesser quantities in different varieties of hops, making some better for bittering than others. In beer, these levels are measured by a standardized system and called international bittering units (IBU) or simply bittering units (BU). Roughly translated, bittering units describe the intensity of the bittering, if not the quality, though because of its sweetness, malt affects the perceived flavor. In very malty beers, like stouts or barley wines, it takes far more BUs to achieve a bitter flavor than it would in a pale ale, which may seem just as bitter. Still, a quick look at a beer's BUs can tell a l about it: Industrial canned fare has perhaps 15 BUs; beers start to become slightly hoppy around 30-40 BUs; above 50 the hop bitterness is very assertive. Next come flavor and aroma. Unlike the hardy alpha acids, which need to boil for an hour or more to extract bitterness, the essential oils that give flavor and aroma to beer are volatile. For the purposes of giving beer flavor and smell, brewers add these hops much later in the boil, perhaps in the last minute or two in the case of aroma hops. In beer, the flavor from the hops is distinct from its bitterness and actually much more closely related to the smell. The bittering tends to hit the back of the tongue and linger in the aftertaste. The taste may touch the front of the tongue and be the first note, later to dissipate under the sweetness of the malt. Some descriptions of hop flavors include licorice, pepper, grass, citrus, cedar or pine. Similarly, the aromas hops impart are often delicate and fleeting. It's best to smell the beer first, when the nose is clear and unhindered by the first taste. There are many smells to beer, but the ones from hops will be floral, spicy, citrusy, perfumy, piney and so onfear the skunky, for this is a light-struck beer and not what the brewery intended). Like the flavor of the hops, the aroma may seem to change or evaporate as one drinks the beer. In our neck of the woods, hops have come to be equated with beer. In America hops only grow in Oregon, Washington and Idaho. So characteristic is it for Northwest beers to feature a sharp hop bite that we've begun to create our own regional style. There's more to it than bitterness; many of our hoppy beers have relatively low bitterness but lots of hop flavor and aroma. Still others have a kind of bracing bitterness that's very complex on further analysis. Even some staid lager styles brewed here have begun to creep up the hop charts, certainly flouting German tradition. Of course, there are also plenty of beers on the market that aren't characterized by hops, beers that put the malt first and foremost. I think. I've never tried one myself, but that's what I hear. |
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