A identificação do receptor de odorante humano para geosmina aumenta a compreensão da qualidade dos alimentos e da água

Researchers from the Leibniz Institute for Food Systems Biology at the Technical University of Munich have made a significant advancement in understanding the human sensory perception of geosmin, a volatile compound known for its “earthy” or “musty” odor. Led by Dietmar Krautwurst, the team has identified and characterized the specific human odorant receptor responsible for detecting this compound.

Geosmin, a compound produced by soil microorganisms, is commonly associated with the scent of rain on dry soil. It is also present in certain plants, such as cactus flowers and red beets. This compound influences the behavior of various animals; for example, it serves as a warning signal for fruit flies about spoiled food, while camels are attracted to water-rich areas due to the presence of geosmin. Lena Ball, a first author on the study, notes that this indicates geosmin functions as a chemical signaling substance across different species, including humans.

The presence of geosmin can significantly impact the sensory quality of food and water. According to Stephanie Frank, a food chemist at the Leibniz Institute, even minute concentrations—between 4 to 10 ng/L—are detectable by humans, which translates to the equivalent of a teaspoon of geosmin in the volume of 200 Olympic-sized swimming pools. Its detection is particularly problematic in products like fish, beans, cocoa, and various beverages, where it diminishes overall sensory acceptance.

Despite its known effects, the receptor that enables humans to perceive geosmin was previously unidentified. The research team has now conducted a comprehensive receptor screening, identifying the OR11A1 receptor as the sole human receptor responsive to geosmin. The team also tested this receptor against 177 other odorants, finding that only 2-ethylfenchol, another earthy-smelling compound, activated it significantly.

The study also included comparative analysis with receptors from other mammals, such as the kangaroo rat and polar bear. These comparisons revealed that the human OR11A1 receptor is less sensitive to geosmin compared to receptors from other animals, such as the kangaroo rat, whose receptor was approximately 100 times more sensitive.

The findings highlight the biological significance of geosmin as a signaling substance and suggest potential applications in developing detection systems for monitoring food quality and water safety. This research could contribute to advancements in ensuring the quality of food products and the management of freshwater resources.