If you’ve smelled floral absolutes such as rose or jasmine, you know they don’t smell the same as putting your nose in a fresh flower. The process of extracting the floral absolute yields a different chemical composition than the combination of constituents that is floating in the air right around a flower in what people call the “headspace.” Now that we can actually analyze the air around a blossom, we can measure what is in the headspace of a flower and use that information to accent floral absolutes to make them more like real fresh flowers, or to build floral accords for flowers that yield little to no absolute, or to simplify a floral accord down to a few basic ingredients that merely suggest aspects of that flower to complement the rest of the fragrance composition.
Headspace analysis may not trap all the scent components exactly as you smell it, so headspace analysts sometimes compare the headspace measurements to the chemical breakdown of absolutes to find a balance between the two that will best approximate the scent of the fresh live flower. Sometimes chemicals that are found in very small amounts have a huge impact on the flower’s scent, as in rose ketones for roses.
When researchers measure the headspace of living flowers still attached to the plant, they find differences depending on what time of day they take the measurements; flowers often peak in scent at the time of day or night when their pollinators are active. And of course, cut flowers rapidly change with time, producing different headspace results than living flowers. Headspace measurements also vary with region in which the plant is grown, as well as soil and weather conditions and other conditions specific to that particular year and location.
One problem in translating the headspace into a perfume is that some of the main constituents are short-lived topnotes that dissipate quickly on your skin, making it difficult to duplicate the flower’s scent for any long length of time. Although floral perfumes can be beautiful, we may not find something that exactly duplicates our favorite flower. Sometimes the beauty of floral perfumes is in the creative differences from the real flower; for example, the perfume may be a rich tapestry woven with other notes instead of being a soliflore, or it may be a creative interpretation of a soliflore that emphasizes certain aspects of the real flower and minimizes others.
I’ve thought about all these issues in the context of working on gardenia, especially since gardenia absolute is not commercially available (except for one very new and expensive source I mentioned here on the blog a while back). In a post soon I’ll delve more into the gardenia headspace components.
Updated to add: photo above is the old centifolia rose Fantin Latour in my garden (copyright Sonoma Scent Studio). Wonderful fragrance but just blooms once per year in spring. Gets to be huge here in California and covers itself with blooms.
Perfume in Progress 
Useful.