Basic Taste Qualities

As previously mentioned, there exists four basic taste qualities: sweet, sour, salty, and bitter. Taste sensations are usually a mixture of these various qualities. Each quality is elicited from a specific type of compound. Sour taste is produced by the hydrogen ion concentration in acids and salty taste is elicited by metal ions. Many organic substances elicit the sweet taste: sugars, alcohols, some amino acids, saccharin and some lead salts. Alkaloids such as quinine, nicotine, caffeine, morphine, and strychnine produce bitter tastes. There also exists nonalkaloid substances such as aspirin which give a bitter taste.

BASIC TASTE QUALITIES

Different regions of the human tongue very in sensitivity to the four basic qualities. The tip of the tongue is particularly sensitive to sweet substances, and the middle parts of the outer edges are most responsive to sour stimuli. Salty stimuli are most effective in an area on the edge of the tongue that partially overlaps these two regions. Bitter substances affect most strongly the receptors near the base of the tongue, in the region of the vallate papillae(Barlow, H.B. et al.).

Concerns for Sensory Evaluation:

• Concentration of the taste stimulus affects sensory perception.
  
• Conditions in the mouth which affect taste perceptions include the temperature, viscosity, rate, duration, and area of application of the stimulus, chemical state of the saliva, and the presence of other tastants in the solutions being tested.
  
• Aguesia, the absence of the sense of taste, is very rare.
  
• Taste sensitivity variability is great especially for the quality of bitterness.
  
• Oversaturation of taste receptors can occur especially with bitterness, which may bind to receptor cells for hours or even days.
  
• Sensory tasters should take small sips and keep each sip in the mouth for only a couple of seconds, then wait for 15 to 60 seconds before tasting again, depending on the strength of the sample.
  
• The first and second samples are the most sensitive and mental comparisons and evaluations required by the sensory test should be made in those sips.
  
• These considerations should be taken into account when devising or participating in sensory evaluation.

Sensory Physiology Nancy L. DeVore

Updated 8/29/97. Send mail to Food Resource, Oregon State University, Corvallis, OR.