A study of iris – from crop to perfume

iris-flower

Good morning students! Please take your seats, take out your notebooks and open up your minds to learn something new. Welcome to room 20, where you are going to take advanced iris class today. Why iris? – someone may ask. We are taking a study of iris because according to Undina-ian calendar February of 2018 is proclaimed as a Month of Irises. My name is Mr. Chemist and I will be your teacher for today. I assume that you all love iris if you’re here today, which is an ideal situation for any teacher – to have a group of students who really want to learn something about the topic.

The name iris derives from ancient Greece where it meant ‘rainbow’ and where it was also used as the name of the goddess of the rainbow, Irida. It is believed that iris was given as a name of this flower due to its multiple possibilities of blooming colors. Oddly enough iris flower is considered odorless. Other animals with more sensitive noses can probably smell it but for humans it’s basically impossible to detect an iris scent from a flower. How can it be used in perfumery then? The truth is that most important part of iris is not its flower, but its root. That’s where all the ‘magic’ happens.

orris-root

Orris root, as it is called by professionals has a long way to go before it will be ready for use in a fragrance & only two species: Iris germanica and Iris pallida are being commonly used for that. After iris blooming time their rhizomes (roots) are being harvested. Once collected they have to be thoroughly cleaned from ground and dirt, peeled, then they are cut into smaller pieces. Clean and chopped iris rhizomes are ready to undergo a process of drying, then aging. Dried root pieces will continue to age in controlled environment for as long as 3 to 5 years. At that time chemical reactions will take place.

This is one of the most important parts in a production of iris as a perfumery ingredient, because final efficiency of a harvest is depending on how well the reactions inside rhizomes will go. So, anyone knows what types of reactions happen during those 5 years of maturing? Chemical compounds of oils and fats inside orris root usually undergo two types of reactions. First of all there is a degradation reaction – a process in which big, heavy molecules break down into smaller ones due to destroying of some chemical bonding. Second, in my opinion more important process is oxidation.

iris-garden

Oxidation, as you might have guessed from the name of the reaction type is a process in which an atom of oxygen gets ‘attached’ to an organic compound and new bond (usually between carbon-C and oxygen-O) is formed. This leads us to irones – a very important carrier of a fragrance that we associate with iris. Triterpenoids found in orris root slowly oxidize over time and form alpha-irone (below, upper structure) and gamma-irone (below, lower structure). Their general chemical formula is C14H22O. Structurally they are similar to ionones – group of aroma compounds found in rose oil. Scent of irones is described as sweet, floral, woody, iris, ionone. It’s a very valuable molecule.

irones

Once the whole process of aging and maturing of dried rhizomes comes to an end they are steam-distilled. This process draws out fragrant compounds from the inside of orris root pieces. In the distiller receiver you obtain an oily fraction that will solidify when it cools down due to high content of myristic acid (up to 85%) – what you obtain is an iris butter (or iris concrete) which usually has 13-17% of irones. If you wash iris butter with a 95% alcohol you’ll obtain iris absolute, richer in irones (generally up to 75% of them). Orris concrete and absolute possess a heavy, tenacious aroma.

Olfactory profile of both is also reminiscent of violet, since violets also contain irones as one of their fragrant compounds. Iris in perfume is also known for its extreme value. Because 1000 kg of orris root produces only around 2 kg of iris butter (yield of 0,2%) it ranks as one of the five most expensive raw materials. Iris absolute is 5 times more expensive than concrete due to much higher concentration of precious irones. For that reason natural iris is only used in most exquisite and luxurious perfume creations. Modern chemical synthesis found a way to produce synthetic irone (6-methyl alpha ionone) but it doesn’t have the same superb quality as natural product.

orris-roots

Because iris is so expensive it is never used in abundance but even 0,1 – 0,2% of it in a perfume formula will bring a touch of cold elegance with hints of floral, powdery or more buttery tones. I hope you found this class a valuable lesson that will help you to appreciate iris even more. Now that you understand the whole process of obtaining iris butter and iris absolute, as well as motifs behind its price, it should be much easier to love your iris fragrances even more. Before you leave I’d like to share with you this gorgeous journey of iris video from IFF. Professor Undina also asked that you sign on to the attendance list with your iris scent of the day. Class dismissed, off you go!

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Februiris – a Month of Irises

Remember how last year in February we all had fun doing a Month of Roses project together? It was such an entertaining activity to follow the calendar and see what perfumes other people were wearing. And it was mostly thanks to you that it worked out because if I were to do it alone I would’ve quickly ran out of possible scents to wear. The idea of a February project is being taken 1 level up by Undina, who decided to pull off a Month of Irises this month! And being an iris devotee I just really wanted to be a co-author and participant of this event. As Hajuusuri wrote in one of her comments, swapping blogs for a day or doing a project like this feels like a family gathering. That’s true!

irises

In case of Februiris (that’s how I’m going to call a Month of Irises) it’s even more fascinating because despite the fact that others might have different perfume preferences than me, it will gather around those who love a common note – in this case iris. Going through comments of other participants there’s always a chance that someone will mention an iris fragrance I’ve never tried or heard before. That’s how lemmings are being born. Since it’s 17th day of February we’re already going through a 3rd week of the project. So if you haven’t yet joined Undina’s initiative I urge you to rush to her blog to see how we did in week 1 and week 2. And do join the fun in week 3. The more the merrier. So far I’m doing well, I wear different fragrance each day but doubt I can do 28 days that way. Even if I use full bottles, decants and samples I don’t have enough. But it’s fun anyway!

[note] picture found via Gardenista

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