Science makes important first step towards the smelloscope

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Smells make a vivid impression, but are nearly impossible to describe. Scientists have just created 'perfumery radar' - a classification system of smells that may pin down the elusive phenomenon.

The human sense of smell is much derided. Our noses are weak. We lean on our eyesight and our hearing to guide us through the world. One of the things holding back our ability to smell is the fact that smell is often so personal. There are some scents that the majority of people can recognize - roasting meat, smoke, maple syrup - but most scents remain undefinable. Unless people know the provenance of the smell, like food odors, there are relatively few words that describe what the smell is.

The words that humans do use to describe scents are heavily influenced by a person's experience and preferences. Expose an outdoorsey person to the smell of wet wood chips and they might describe the smell as 'organic' or 'green'. A city person, on the other hand, might associate those smells with the scents of vegetables left too long in the fridge and describe them as 'rotten' or 'stale'.


Even among people who smell things for a living, there is a wide variety of classifications for different smells. Over the years, odors have been classified into 'families,' smells that had common elements. Families were given all kinds of labels; putrid, resinous, oriental, floral, minty, camphoraceous. Little agreement could be reached between people that 'this' odor, even simple odors, belonged in 'that' family. When perfumes started layering scents, the classification became that much more difficult.


A new method, developed by researchers at the University of Porto, combines 'physicochemical models and qualitative descriptors,' to classify perfumes into families that can be universally recognized. It also incorporates their odor intensity and the evaporation process of the various different scens that make up complex fragrances.

The methodology is long, and complicated. It first separates the pure scents combined in a perfume into various basic scents like 'fruity' or 'citrus.' The perfumes are then subjected to gas chromatographic techniques to single out fragrance components. The researchers take those fragrance compounds and applied the Odor Value Concept, a dimensionless calculation that measures the intensity of the fragrance.


The results of the new methodology lined up very well with the classification of scents done by professional perfumers, and may form the basis of a classification of smells. Every Futurama viewer knows how many lives that could save in the future.

Via Industrial and Engineering Chemistry Research.