Using a concept similar to that used in commercial breath-freshening strips a researcher from Temple University has developed a new method for clinical taste testing.
Greg Smutzer, director of the Laboratory of Gustatory Psychophysics in the Biology Department of Temple's College of Science and Technology has developed taste strips similar to breath-freshening strips.
However, these edible strips contain one of the five basic tastes that are detected by humans - sweet, sour, salty, bitter and monosodium glutamate, which is also known as umami taste.
Smutzer began by using a combination of two polymers, pullulan and Methocel. He created the strips dissolving the polymers, in the form of powders, in warm water and then allowing the solution to cool to room temperature.
Added into the solution is a small amount of a taste stimulus that will give each strip the desired taste: sodium chloride for salty, sucrose for sweet, ascorbic acid for sour, quinine for bitter, and monosodium glutamate for umami taste.
Once the solution is cool, it is then poured onto Teflon-coated pans and allowed to dry five to six hours in order to produce a clear, thin film. When dry, the films are carefully removed, and cut into one-inch-square strips.
Smutzer said that pullulan, a major ingredient of the Listerine breath strips, is tasteless and dissolves within seconds in the mouth. Methocel is added in small amounts to increase the tensile strength of the pullulan films.
According to Smutzer, no standardized method for rapidly measuring taste function in humans is currently available, and taste norms for the human population as a function of age and sex have yet to be determined.
The development of the taste strips therefore solves the problem for researchers.
"What is typically done in the lab is a 'sip and spit' test, where a liquid solution is prepared that contains dissolved tastant. You then place a small amount of the solution, maybe half an ounce, into a small cup for the test subject to place into their mouth, swish around and then spit it out," Smutzer said.
However, he said that this type of test is difficult to administer outside the lab because the solutions have a very short shelf life and are not very portable.
Another big problem with the liquid test is that it cannot be effectively used to examine selected regions of the tongue, such as just one side, the front or the back of the tongue.
"It is very difficult to do regional testing with the liquid test because it is tough to concentrate liquid in just one area of the mouth. We can alter the size or thickness of these strips, place them on a desired area of the tongue and allow saliva to dissolve them without causing the tastant to spread over the surface of the tongue," Smutzer said.
Since different parts of the tongue may respond to different tastes, or may respond more or less strongly to the same taste stimulus.
Smutzer said his taste strips could be used to develop detailed taste maps of the tongue surface, a project he plans to examine in the future.
According to him, another major advantage of this technology is that the strips can measure thresholds for tastants at levels that are from 10 to 100 times lower when compared to a standard "sip and spit" test.
These lower threshold values for sweet, sour, salty, bitter or umami taste could be useful for examining taste disturbances in clinical populations where such disturbances have not been previously identified.
Smutzer added that his strips, which are stored at room temperature and have been used up to six months after being produced, could also be beneficial to the pharmaceutical industry, since certain medications can create temporary taste disturbances.
He said that subjects could be tested with taste strips during clinical trials to determine whether new drugs or therapies interfere with taste function.
The study has been published in the June 2 online "Ahead of Print" edition of The Laryngoscope, the journal of the American Laryngological, Rhinological and Otological Society.