Signal Transduction of Umami Taste: Insights from Knockout Mice

Abstract

The sense of taste is comprised of four basic qualities: sweet, bitter, salty and sour. Umami, a Japanese term for delicious, although controversial for many years as a distinct taste is now widely accepted as a fifth taste quality. Compounds that taste umami include glutamate salts such as monosodium and monopotassium glutamate (MSG and MPG, respectively), nucleotide monophosphate (IMP, GMP), certain peptides and amino acids such as aspartate. A particular property of umami is that the taste of glutamate is enhanced by monophosphate nucleotides. Psychophysical studies and conditioned taste aversion experiments showed that humans and mice distinguish the taste of MSG from the four basic taste qualities. The umami taste may have evolved to help animals ingest food that have high protein content and is of significant importance to the food industry because of its flavor enhancement properties.