Every part of an odor molecule does not stimulate the odor receptors in the nose. Usually a limited part of the molecule stimulates the receptors and send an odor signal to the brain. Referring to the active material in it we can classify the foul odors to three types.
Fatty acids : Sourish odors, sweat odors, olive oil processing industries odors and etc can be named in this class. Generally the source of this kind of an odor is rancidity, various fermentations, sweat and etc. Because the odors in this class cause relatively smaller troubles compared to the other odor problems and are more easily competed, they do not cause serious problems.
Sulfur compounds : These odors are generally formed of organic sulfite and mercaptan. They are generally caused by sources like anaerobic reactions, rotten zucchini and similar plants, decay of dead bodies.
Nitrogen compounds : These odors are generally caused by amines. Practically they are generated from rotten fish, dead bodies, urine and etc. sources.
Besides the above classification of odors, in some rare cases the nitrogen in the reactive part of some of the odor molecules is replaced by phosphore and the sulfur is replaced by selenium. In such cases the odor is even stronger and irresistible.
If we look at the case of odors from the theoretic side, below table can describe if which chemicals cause which odor. |