The sense of smell: contributions of orthonasal and retronasal perception applied to metallic flavor of drinking water

Abstract

The human senses are important assessment tools that assist water industry with effective water quality and water security monitoring. Flavor perception is combination of taste and odor; odor perception is a combination of orthonasal and retronasal perception. Orthonasal perception is associated with the sniff and describes entry of odor molecules though nostrils to nasal cavity followed by interaction with odor receptor neurons. Retronasal perception describes mechanism in which odor molecules present in mouth are transported to back of nasopharynx and then to odor receptor neurons. Although both pathways bring odor molecules to olfactory epithelium where they are perceived and processed by brain, retronasal route is more important for humans in terms of detecting ingested odors. For copper (II), metallic flavour is a combination of a weak bitter taste and a strong metallic odor that is produced as a biochemical reaction in mouth. Copper (II) in presence of oxygen causes lipid oxidation of arachidonic, linoleic, and oleic acids in mouth. A more thorough understanding of sense of smell will greatly aid water industry in its quest to produce a palatable product.