With the help of mathematics, researchers categorized odors

Jason Castro, Bates College, Chakra Chennubhotia, University of Pittsburgh, and Arvind Ramanathan, Oak Ridge National Laboratory, published in PLOS ONE journal that there are about 10 basic categories of odor. The researchers used mathematical method to simplify the olfactory information into coherent categories. This is similar to the technique of compressing digital audio files or image file without losing the quality. The 10 basic odors as identified by the team are: fragrant, woody/resinous, fruity (non citrus), chemical, mint/peppermint, sweet, popcorn, lemon and two kinds of sickening odors: pungent and decayed. Castro says, "It's an open question how many fundamental types of odor qualities there are. This is in striking contrast to olfaction's 'sister sense,' taste, where we know that five basic qualities seem to organize sensations. According to Castro, the world of smells is tightly structured which is organized by a handful of basic categories. Now the researchers are trying to apply this finding to a range of chemical structures so that they can predict how a particular chemical is going to smell.