Here is what the folks at Hop Tech
http://www.hoptech.com say about it:
Home :: Hop Oils, Essences and Extracts :: Late Hop Essences
HopTech's Late Hop Essences are the soluble portions of the hop oil that contribute to a beer's late hop character, usually imparted by hops added late in the boil. Depending on the essence's composition, two effects are possible. The "floral" essence adds a subtle floral taste (not aroma), and is not the same kind of "floral" aroma you get with our hop oils. It's really hard to describe, you'll have to try it. The most pronounced effect comes from the "spicy" essence. This has a dramatic effect on the beer's "mouth feel" adding a body and complexity that is truly amazing. It can really "perk up" a beer (when added to Bud, no one ever guessed it was Bud, even when served from a Bud bottle!). Useful effects occur at very low levels, from 50 to 100 parts per billion (ppb) of the active constituents, and you can mix them for combined effects. As with our hop oils, we have formulated these essences to make them easy to add to your beer. 1 tsp adds 50 ppb to five gallons. Add just prior to bottling or to the serving keg. Supplied in 2 oz dispenser-top bottles, enough for 30 gallons of beer at 100 ppb.
This would be great information except that who knows how many ppb you need in your beer. These being late hop essences, you won't get much in the way of bittering. That's why IBU's aren't listed for that product. The spec sheet I have here says to experiment using an eye dropper to dose a 12 ounce glass to taste. It has been a couple years since I used the stuff so I don't remember how much I used. I do remember that it doesn't take much.
Wayne
