Olfactive Chemistry: Geosmin- After the Storm

Posted on by in Mark Behnke, Olfactory Chemistry and tagged , , , , .

As we come to the end of the first half of 2016 there has been an interesting trend from some of my favorite indie perfumers. There has been more usage of the aromachemical geosmin to different effect. Geosmin is one of the more interesting ingredients on the perfumer’s palette.

Everybody is familiar with the smell of geosmin in Nature. It is that smell in the air which hangs after a heavy rain. It comes about because there is a natural bacteria, Streptomyces, which leaves geosmin behind when it dies. The longer the dry spell the more the chemical is on the surfaces. If a thunderstorm comes along it releases the geosmin into the air. This is that smell also called petrichor. It is earthy and mineralic in turns. The actual chemical structure is below.

decalin geosmin

Geosmin is two six membered carbon rings fused together into a structure called a decalin. Then two methyl (CH3) groups and one alcohol (OH) are what it takes to transform the slightly mentholated odor of decalin into the after the rain smell of geosmin.

The isolation of geosmin is a fascinating study of the ancient and the modern. The ancient way comes from India. Dried out disks of earth which the monsoons have covered and now evaporated are produced. These disks are them placed in primitive distillation apparatus to form what is called mitti attar. This is the earliest isolation of geosmin. There is a great story in The Atlantic from April of 2015 which describes the entire process in detail.

The other way is by mimicking the natural bacteria to make it via biosynthesis. Professor David Cane and his group at Brown University discovered an enzyme from the natural bacteria Streptomyces coelicor. (Journal of the American Chemical Society, vol. 28, pg 8128-8129, 2006) This is the enzyme which transforms the non-cyclic farnesyl diphosphate into geosmin. The study of the transformation of farnesyl diphosphate into natural chemicals has led to the ability to imitate these processes to produce natural products for medicinal as well as olfactory purposes. In the scheme below you can see the process that the enzyme geosmin synthase uses to convert the acyclic to the cyclic. Now geosmin is readily available as a perfume ingredient.

farnesyl to geosmin

The odor profile of geosmin allows it to be used in marine styles of fragrance as perfumer Christi Meshell does in her House of Matriarch Albatross. In that perfume she uses it as the smell of the rocky coast of the Pacific Northwest. Shelley Waddington also is inspired by the same locale and her use of geosmin carries the damp forest milieu in En Voyage Rainmaker. Perhaps my favorite use so far this year comes from Zoologist Bat where perfumer Ellen Covey working under Victor Wong’s creative direction uses geosmin as a key component of the wet cave accord which grounds that fragrance.

If your fragrance carries the smell of after the storm geosmin is probably the reason.

–Mark Behnke

New Perfume Review House of Matriarch Albatross- Getting Littoral About It

Posted on by in Mark Behnke, New Perfume Reviews and tagged , , , .
2

One of my wishes every year is for one of the cadre of independent perfumers to have a mainstream success. One of the first steps towards this is for these perfumes to become more readily available to the perfume consumer. Which means it somehow has to make it to the mall. There have been a few who have taken the initiative to do just that. One of the most current efforts is independent perfumer Christi Meshell’s House of Matriarch launching a collection of nine fragrances, old and new, in Nordstrom’s across the country. I am rooting for Ms. Meshell because she has developed into an assured artist over the time I have followed her fragrances. I believe she offers an alternative to what else will be found on Nordstrom’s fragrance counter. If these can entice a few of those consumers over to something less commercial in aesthetic this could be the start of my wish coming true.

One of the ways to coax someone into becoming more adventurous is to give them a different riff on a style they know well. One of the perfumes, House of Matriarch Albatross, attempts this with the woody aquatic genre. Ms. Meshell was inspired by the Salish Sea area of her native Pacific Northwest. In that area of the world the pine trees grow right down to the rocky shoreline while the slate grey cold ocean laps against the craggy strand. This zone where the land meets the water is called the Littoral zone. Ms. Meshell uses Albatross as a literal interpretation of the littoral of the Salish Sea.

Christi-Meshell

Christi Meshell

What separates independent perfumery from the mainstream is the ability to use unusual ingredients. Ms. Meshell doesn’t conjure the ocean by throwing a ton of Calone into Albatross and moving on. Her marine accord accentuates the cool salinity of the ocean water and not the warm sea spray so prevalent within the aquatic genre. It is that chilly watery accord which opens Albatross. This then captures the evergreens on the shore with a mixture of cork oak and pinon oil. This has a sharp woody quality which is the perfect conjuration of this milieu as the cold breeze bites a bit when you breathe deeply. Albatross has a similar bite as the pines ride the wave of the marine accord. Over a few hours the pine mellows and dries out into what Ms. Meshell calls a driftwood accord. What this means is early on the pine accord is sappy. By the later parts of the drydown that sappiness is gone leaving a drier more austere version of the pine.

Albatross has 10-12 hour longevity and average sillage.

I’ve never visited the Salish Sea but I’ve spent a lot of time in the East Coast version of the Littoral zone of Acadia National Park in Maine. Albatross accurately captures that intersection of brine and pine, literally.

Disclosure; This review was based on a sample provided by House of Matriarch.

–Mark Behnke