A new approach to taste testing

Greg Smutzer, director of the Laboratory of Gustatory Psychophysics in the Biology Department of Temple University’s College of Science and Technology, has created taste strips similar to breath-freshening strips, but 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.

This research, A Test for Measuring Gustatory Function, has been published in the online 'Ahead of Print' edition of the journal of the American Laryngological, Rhinological and Otological Society, The Laryngoscope.

The idea was born when a laboratory equipment repairman, who was a friend of Smutzer’s, stopped by the laboratory more than four years ago and offered him one of the new breath-freshening strips.

He said, “You have to try one of these,” Smutzer recalled. “I had never seen the strips before. But as soon as he showed them to me, one of my first thoughts was, this technology would be ideal for a taste test because it is so simple to use.”

Smutzer starts by using a combination of two polymers, pullulan and Methocel. His strips are created by 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.

He 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.

The development of the taste strips solves a problem for researchers. According to Smutzer, no standardised 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.

An advantage of this technology, according to Smutzer, 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.