Good Day, I found a WIKI article, and cut/pasted, and added Chemisty Data with brief desciption of Hop oils.......
http://www.homebrewtalk.com/wiki/index. ... _chemistry
Added "world" Temperatures
The alpha acids are the hop components most familiar to home brewers. Every package of hops sold to homebrewers indicates the alpha acid percentage to allow the brewer to calculate the bitterness he or she wants in the finished beer. The alpha acid percentage represents the amount of the hop, by weight, that is composed of alpha acids.
Humulone (R=isovaleryl) is the primary alpha acid occurring in most hops. It is thought to give a desirable "soft" bittering to the finished beer.
Melts above 153F/67C, Never boils off
Cohumulone (R=isobutyryl) has been considered to add a harsh, unpleasant bitterness to beer, and so low-cohumulone varieties were considered more desirable for brewing purposes; most noble hops have relatively low cohumulone. For this reason, cohumulone is often the only alpha acid identified specifically by hop producers. Cohumulone is indicated as a percentage (by weight) of the total alpha acid content of a hop.
Melts above 158F/70C, Never boils off
Adhumulone (R=2-methylbutyryl), which usually occurs in relatively small amounts. Its effect on bitterness and flavor is not well understood.
Melts above 208F/96C, Never boils off
Each alpha acid has a corresponding iso-alpha acid. The iso-alpha acid isohumulone, the isomerized form of humulone, is important to brewers because it reacts with riboflavin in the presence of light to form MBT to form a skunk-like flavor and odor.
While alpha acids contribute most of the bitterness to beer, most of the hop flavor and aroma is contributed by volatile essential oils. Hop producers generally indicate the total percentage of essential oils by weight in a given hop, and sometimes identify specific oils by percentage of total oil.
Because hop oils are highly volatile, traditionally the aroma and flavor characteristics of hops were obtained by late hop additions or dry hopping, allowing the oils to be absorbed into the wort but not leaving them in the boil long enough to boil off. Traditionally flavor additions were made in the last fifteen minutes or less of the boil, while aroma additions were made with five minutes or less of boil remaining. However, recently home and craft brewers have been experimenting with the recently rediscovered technique of first wort hopping, which allows hops added early in the brewing process to survive the boil and lend flavor and aroma to the finished beer.
The principal hop essential oils are:
Humulene is thought to lend the distinctive "noble" character to noble hops; most varieties traditionally considered noble are high in humulene, while many bittering hop varieties have very low levels. The noble character is strongest when the hops are used in dry hopping or late hop additions; if boiled for longer periods, humulene lends the finished beer an herbal or spicy character.
Melts above 168F/75C, Boils off at 194F/90C
Myrcene yields flavors that were not traditionally considered desirable by European brewers, and noble hops are very low in myrcene. However, many American hop varieties are very high in myrcene; it makes up up to 60% of total oil in Cascade and up to 70% in Amarillo. Also found in some citrus fruits, myrcene lends American hops many of their distinctive flavors.
Melts above 80F/26C, Boils off at 120F/50C
When added late in, or after, the boil, myrcene adds the intense, pungent aroma associated with American dry-hopped beers. When boiled for longer periods, it yields the characteristic citrus and pine aromas of American craft beer.
Caryophyllene adds a spicy, herbal character similar to humulene when boiled. Its effect on flavor when fresh is not well understood.
Melts above 130F/52C, Boils off at 205F/96C
Farnesene makes up a very low percentage of total oil in most hop varieties. However, it is considered significant because it makes up a substantial proportion of some noble hops. Its effect on flavor and aroma is unknown.
Melts above 190F/85C, Never boils off
For a list of Hops with Oils listed see...
http://www.usahops.org/graphics/File/HG ... -24-12.pdf
Sorry for the long "old School" post, Please add or remove any thing that you can. It will help.
Honest Officer, I swear to Drunk, I am Not God.