Uniquely identifiable characteristics

Distinguishing Feature : The aromatic light-green cones that hang downwards after flowering.

Not to be confused with: Hop Trefoil [a plant with similar name belonging to a different family]

Hop is a climber without tendrils, it climbs by wrapping itself clockwise around a supporting branch or stem of any other plants nearby aided by the stiff short backwardly directed spines on the stems. This mode of climbing is represented by the word bine; therefore it should be known as Hop bine, rather than Hop vine. Vines climb by the use of tendrils and suckers, which Hop bines lack.

The hops themselves are actually the female flowers or seed-cones (more accurately strobiles). They are extremely light in weight for their size. Hops are aromatic if crushed.

The stems are angled, with very short rough spines facing one way which helps it to cling on to whatever stems it is climbing up.

Hops are used as the main aromatic flavouring element in ales, beers, lagers, stouts, entires, porters and some other alcoholic drinks. It is hops which impart the bitterness to bitter. Fresh green cones are usually used for the best beers. There are many varieties grown commercially, especially in Kent, but also in other parts of the world especially for lagers.

Hops have been used as the bittering component to flavour beers since the 8th or 9th century. They also exhibit an anti-biotic and anti-septic effect which helps preserve the beer. Before hops were used, a wide variety of other herbs were used to flavour 'beer', such as Dandelion, Horehound, Burdock root, Marigold, Ground Ivy, Heather, Bog Myrtle, Spruce, Bogbean, Broom, Stinging Nettle, Yarrow, Wood Sage, Mugwort, Horehound (the Marrubium vulgare type of Horehound rather than Black Horehound which smells repugnant!), and many others. It is still possible to obtain Spruce Beer in parts of Scandinavia and America, but, un-like hops which have a soporific effect reducing one to sleep before drinking too much, spruce has an up-lifting effect, and is probably more dangerous from a point of view of alcohol poisoning.

Other adjunct herbs such as Henbane, Deadly Nightshade!!, Juniper berries, Ginger, Caraway seeds, Aniseed, Bergamot, Horse Mint, Rosemary, Nutmeg or Cinnamon were sometimes added for extra flavouring, and indeed some are still used for speciality beers, although the author would prefer not to drink any brewered using Deadly Nightshade! [some of the above are probably outlawed now].

The following is a list of all hop varieties grown commercially for the brewing trade: Czech Saaz, US Saaz, Tettnanger, German Tettnanger, Cluster. Styrian Gold, Suoper Styrian, Strisslespalt, Spalt Select, US Spalt, German Spalt, Kent Golding, US Hallertau, Perle, Progress, Liberty, US Hersbruck, German Hersbruck, Lublin, US Fuggle, British Fuggle, German Mittelfruh, Galena, Mt. Hood, Cascade, German Tradition, Huller, Willamate, Crystal, Challenger, Target, Pacific Gem, Brewer's Gold, Pride of Ringwood, Northern Brewer, Northern Brewer Hallertau, Columbus, Centennial, Nugget, Eroica, Chinook and Bullion. All have differing proportions of the main flavour components, both good and bad, many of which are shown below.

Along with Hemp, Hop is the only (UK) member of the Hemp Family.

Myrcene is an olefin monoterpene that is contained in plants of Genus Myrcia (with no representation in the UK), Verbena, Hop, Hemp and Bay Laurel. It has a pleasant odour and is used in perfumery. Although myrcene has a high presence in hops, up to 30%, it is highly volatile and does not usually survive in the finished beer, although its degradation and oxidation products such as linalool, Geraniol and geranyl isobutyrate do. Linalool is a terpene alcohol with a floral slightly spicy smell found in many plants including the peel of citrus fruits and especially in Lavender and used as a scent in perfumery, soap and toiletries, and as an insecticide for fleas and cockroaches. Farnesene is a green sesquiterpene found in the skin of Apples and is responsible for their greenness and odour. Damage to the fruit results in the release of Farnesene contained within cells, the subsequent oxidization of which turns the fruit brown. It acts both as an insect repellent and pheromone. Potatoes and other similar species synthesize Farnesene as an insect repellent. Farnesene is also volatile and degrades into innumerable other compounds during brewing. All three are present in Hop and Hemp.

Humulene otherwise known as alpha-Humulene, is a caryophyllene, this time a mono-cyclic sesquiterpene. It is present in Hop and Hemp, contributing to their aroma, taste and bitterness. humulene has a greater percentage in noble hops than myrcene, but it too degrades during the boiling process in beer production, the oxidation products of which survive, imparting several desirable characteristic flavours to the finished beer.

Caryophyllene, otherwise known as beta-caryophyllene is a bi-cyclic sesquiterpene found in Hop, Hemp, Rosemary, Cloves, Caraway, Origano and also contributes to the spiciness of Black Pepper. Amounting to between 5% and 15% in hops, caryophyllenes oxidation products contribute to the herbal spicy flavour of beer.

All four of the above compounds, humulene, caryophyllene, farnesene and myrcene are present to various percentages in hops and contribute to desirable flavours, aromas and sensations in ales. These compounds constitute the major constituents of the essential oils of hops, of which there are over 300, including the terpene alcohol linalool at 1%. Linalool is used in perfumes, such as eau-de-cologne.

Related to Humulene and Farnesene are the Alpha-acids which is why Humulene is sometimes referred to as Alpha-humulene, whereas the Beta-acids are related to Caryophyllene, sometimes called Beta-caryophyllene for much the same reason. The alpha- and beta-acids are the resins in hops, as opposed to the essential oils mentioned above.

Alpha-acids	Beta-acids
The alpha-acids humulone, cohumulone and adhumulone are present in hops. They are not very soluble in water, but during the wort boiling phase of brewing are and are converted to the much more soluble and bitter compounds cis-isohumulone and trans-isohumulone. The cis- and trans- forms of isohumulone are in chemical equilibrium and contribute much to the bitterness of beers.	The beta-acids lupulone, colupulone and adlupulone are also present in hops but are much less bitter than their alpha-equivalents, tend to precipitate out in the wort and are partially oxidised in the brewing process to become delta-acids (hulupones). The products of oxidation of beta-acids do influence the taste and aroma of beer but to a much lesser extent, and are not present in hops themselves so have no representation here.

Both cis- and trans-Isohumulone are formed in the brewing process, and are the result of boiling the largely insoluble (in water) humulone. Isohumulone is much more soluble in water and contributes much to the desirable bitterness to beers. Note that humulone has a six-membered ring, whereas the product Isohumulone has a 5-membered ring. Rather unfortunately, Isohumulone is very susceptible to cleavage into a pair of radicals when subjected to light in the presence of Riboflavin, a chromphore present in beer. These radicals then react with Cysteine, an amino acid which is also present in beer, to form a most un-desirable product, 3-methyl-but-2-ene-1-thiol, which is a sulphurous mercaptan (prenyl mercaptan) which imparts an un-pleasant and un-desirable musky flavour and aroma to the beer. The use of brown glass bottles prevents this, but not green. Beer sold in clear bottles is usually specially made using hydrogenated hop extracts which prevent this reaction occurring. Prenyl Mercaptan is a musky smelling chemical and highly undesirable product in beer that has been exposed to light for extended periods and is one of the reasons why beer is supplied in brown bottles. It has an intense sulphurous, leek or onion-like odour and is responsible for the so-called 'sunlight' flavour of beers exposed to light. The aroma threshold is exceedingly low, being detectable by smell at concentrations of only 0.05ppm.

Prehumulone, Posthumulone, prelupulone and postlupulone are also acids found in hops. All the acids are fairly weak acids, having a pH of around 5.

minor Alpha-acids	minor Beta-acids
Prehumulone and Posthumulone are minor-constituent alpha-acids that still contribute towards the taste of ales.	Prelupulone and Postlupulone are minor-constituent beta-acids.

Xanthohumol is a prenyl chalconoid and yellow-coloured substance that is present in the yellow pollen grains to be within the female hop flowers (the hops) inside the glands near the centre. It is also present in the beer, and has anti-oxidant, anti-bacterial and anti-fungal effects. It is claimed to have health benefits.

The sesquiterpenes Cardinene, Muurolene and Selinene, which are present in hops, may also contribute to the flavour of beer in ways not fully understood.

Hop varieties with a high α-acid content (which are used for cheap beers) include Cluster, Chinook, Eroica, Galena, Nugget, Yeoman, and Brewers Gold. Hops with a lower α-acid content (which have a stronger aroma and flavour qualities) include Fuggles, Hallertauer, Saaz, Tettnanger and Goldinds.

Hops deterioate in storage. However, lambic brewers do what to most brewers would be anethema: they age the hops for several years before use, which changes the flavour profile and alters the bitterness profile. Lambic brewers use these aged hops primarily for their preservative properties.

AROMA & TASTE PROFILES OF ALES The aroma profile of beers is multi-dimensional and attempts to measure the various proportions (on a sliding 0-4 scale) of the following: Alcohol/Solvent, DiMethylSulphoxide (DMS), Other Sulphur, Cereal/Grainy, Malty, Woody, Fresh Hop, Grassy, Herbal, Spicy, Floral/Scented, Pear/Apple, Citrus Fruits, Soft Fruits and Tropical Fruits aromas. The taste profile of beers is also multi-dimensional, attempting to determine the various proportions (on a sliding 0-6 scale) of the following tastes: Alcohol/Solvent, DiMethylSulphoxide (DMS), Other Sulphur, Cereal/Grainy, Malty, Woody, Fresh Hop, Grassy, Herbal, Spicy, Floral/Scented, Pear/Apple, Citrus Fruits, Soft Fruits, Tropical Fruits as well as extra items not in the aroma profile: Linger, Body, Astringent, Mouthcoating, Sour, Bitter and Sweet. Various characteristics are undesirable, such as 'DMS' or 'Other Sulphur' smells. Woody I like! Some beers taste a little like oak-matured whisky. Excellent! Strange no mention of Peaty. I like peaty too!

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