taste vs. flavor

• Taste


  Sensations evoked by solutions in the mouth that contact receptors in the tongue (and roof of the mouth) that then connect to axons in Cranial Nerves VII, IX, and X
• Taste


  • Discerning which chemicals we need to ingest because they are nutritious, versus which we need to spit out because they may be poisonous
• Liking "sweet"

  Hardwired into our brains, but we learn to like the chocolate flavor of the cookie based on experience
• We eat chocolate paired with sugar, fat and starch, which are sources of energy
• Taste and flavor actually holds the key to our survival
• Flavor

  The combination of true taste (sweet, salty, sour, bitter) and retronasal olfaction
• Retronasal olfaction

  Exhaling odorant molecules into our mouth, where they can travel up into our upper nasal cavity
• Aristotle didn't realize that the chemicals emitted by food was actually an odorant (e.g. volatiles)
• Volatiles can rise up behind the palate and enter the nose from the rear
• Orthonasal olfaction

  The detection of odorant molecules inhaled through the nose
• Retronasal olfaction


  Produced when volatiles released into the air inside our mouths, travel up through the retronasal passage into the nose, where they then move upward and contact the olfactory epithelium
• Retronasal olfaction is attributed to food and is combined with taste sensations to create "flavor"
• The difference between taste & flavor wasn't corrected until

  1812
• A student at Edinburgh University noticed that sensations from a spice like nutmeg was abolished when you plugged your nose
• Student concluded that the sensation evoked by nutmeg should be called a "flavor" and not a taste (William Prout)
• Plugging the nose prevents the airflow that carries odorants through the retronasal passage
• Gustation

  The sense of taste
• Gustation also draws on our sense of smell
• Taste sensors make a significant contribution to flavor perception
• Chewing

  Breaks down food substances into molecules that can be dissolved in saliva
• Taste Buds


  A globular cluster of cells that has the function of creating neural signals conveyed to the brain by taste nerves
• There are ~10,000 taste buds
• Taste buds are found on your tongue, the roof of the mouth, and the back of the throat
• Papillae

  Embedded in the papillae (gives the tongue its bumpy appearance)
• Types of papillae

  • Filiform- no taste function
  • Fungiform- tip of tongue, mushroom shaped
  • Foliate- sides of tongue, series of folds
  • Circumvallate- back of tongue, large and circular
• Taste cell

  A cell within the taste bud that contains sites on its apical projections that can interact with taste stimuli
• Taste receptor cells (TRCs) die and are replaced regularly (about every 10 days)
• Taste receptor cells respond to a limited number of molecule types
• Preferred molecules

  When a TRC comes in contact with one of its preferred molecules, it creates a message that travels along one of three cranial nerves to the brain
• Taste cells are clustered around a central pore (taste pore) that is continuous with the skin surface
• The taste cells extend several microvilli that are studded with taste receptor molecules
• Activation of these taste receptors and taste cells generates sensation of: sweet, umami (ie, savory), bitter, salty, and sour
• D.P. Hanig, 1901 measured taste thresholds for sweet, bitter, salty and sour all around the perimeter of the tongue
• D.P. Hanig plotted curves to show how taste qualities varied across tongue locations in 5 participants
• Edwin Boring, Sensation and Perception in the history of Experimental Psychology (1942) was responsible for a taste urban legend (bumbumbum...)
• Taste qualities

  • Sweet
  • Sour
  • Salty
  • Bitter
  • Umami
• The "tongue" map by Boring. Different areas of the tongue respond to different taste qualities
• differences in Sensitivity to 4 major tastes (Boring)

  Taste thresholds do vary across different tongue locations, the variation is actually quite small
• Thresholds only showed the lowest detectable taste concentrations rather than tastes experienced in the real world
• Real world taste intensities are produced by the summation across fibers with varying thresholds