According to BBC media reports, after a long dry weather, fresh air and moist soil will give off a pleasant smell, why? This all started with some chemical reactions in which the role of small organisms called bacteria, our plants, and the lightning in the sky is equally important in it. Because of the long-lasting charm of this smell, scientists have been trying to reveal the secrets even perfumers want to catch this smell their bottles to know about its truth.
For the first time in the 1960s, this wet earth fragrance named as petrichor by two Australian. According to them the when the rain hits the dry ground, it produces a warm earthy aroma and the main reason for this is bacteria. The name of researchers was Isabel Bear and Richard Thomas.
Professor Mark Buttner, director of molecular microbiology at the John Innes Centre, explained, “These organisms are abundant in the soil,” he told the BBC reporter. “People smell it. The moist soil smell is actually a molecule produced by a certain kind of bacteria. The molecule is called geosmin, produced by Streptomyces. Streptomyces are found in most healthy soils, and they are also used to make antibiotics. The water droplets release the geosmin to the air, and the concentration of geosmin after the shower is much higher than before the rain. Professor Butler added, “Many animals are sensitive to it and humans are particularly sensitive.”
These two researchers also found in the early 1960s, it was sold as a perfume in Uttar Pradesh, India, and had the name Matti ka attar. Nowadays, perfumers are increasingly using geosmin as a spice ingredient.
The perfumer Marina Barcenilla said, “This is a very powerful ingredient. When it is hit by rain, it smells like concrete. It has a very original taste.” She added Tao, “Even if you dilute it to a concentration of one billionth, humans can still smell it.”
We also have a strange relationship with geosmin. Although we are attracted by its fragrance, many of us don’t like its taste. It is not toxic to the human body, however, even the small amount of it makes some people off to drink mineral water or wine. Professor Jeppe Lund Nielsen of Aalborg University in Denmark commented, “We don’t know why people don’t like earth odor.” He added, “It’s not toxic to humans, but somehow we’ll Link it to negative things.”
According to Professor Nielsen’s research, geosmin may also be related to terpenes, which are sources of many plant odors.
Professor Philip Stevenson, head of research at the Royal Botanic Gardens (Kew) in London, said that rain may allow plants to emit these aromas. He told the BBC, “Usually, good phytochemicals are produced by leaf hair. Rainwater can destroy these chemicals and release compounds. The substance, just like you crushed dried herbs, the smell becomes stronger. “A very dry period can also slow down the metabolism of plants. Rain after a long drought will speed up metabolism and release a pleasant smell.
Also according to researchers, the lightning means thunderstorm also play an important to the role. During the Lightning and other discharge phenomena in the atmosphere produce a clean, intense ozone odor.
Professor Maribeth Stolzenburg of the University of Mississippi explained, “In addition to lightning, thunderstorms, especially rain, will improve air quality. Most of the particles, such as dust and aerosols, are carried away by the rain, air. It will become fresh.”