Fatty acid molecules released during cooking may be enhancing the formation of clouds, which have a major cooling effect on the planet, according to a study. Scientists demonstrated for the first time that fatty acid molecules emitted from from deep fat fryers during cooking can spontaneously form complex 3-D structures in atmospheric aerosol droplets, according to the study published in the journal Nature Communications.
The team believes that the formation of these highly ordered structures is likely to extend the atmospheric lifetimes of these molecules and affects how clouds form. "It is known that fatty acid molecules coating the surface of aerosol particles in the atmosphere may affect the aerosols ability to seed cloud formation," Christian Pfrang, from the University of Reading in the UK. "However, this is the first time scientists have considered what these molecules do inside of the aerosol droplet, and we have shown that they may be assembling into a range of complex, ordered patterns and structures. This means they may last longer in the atmosphere," Pfrang said.
The researchers studied a model system to represent atmospheric aerosol consisting of individually levitated droplets of mixtures of brine and oleic acid, a fatty acid associated with cooking emissions. They observed that the fat molecules assembled into highly ordered "lyotropic" phases - crystal-like lattices of spheres or cylinders which are known to strongly affect water uptake from the surrounding environment, a key process in cloud nucleation, and viscosity, which affects chemical reaction rates.
Further experiments showed that the fatty acids were more resistant to chemical attack by ozone, and therefore can survive longer and travel further in the atmosphere, if they adopt these complex structures. The extended lifetimes of these molecules may facilitate droplet growth and thus cloud formation.