Assessment of gustatory function by means of tasting tablets

To develop a simple test for the screening of gustatory function in clinical settings.

We tested 101 healthy volunteers (44 male and 57 female volunteers; mean age, 47 y) with the following gustatory test: the substances sucrose (sweet), citric acid (sour), sodium chloride (salty), and caffeine (bitter) were presented as tablets (diameter 4 mm) similar to common sweetener tablets. For quantitative assessment of whole-mouth gustatory function we used six different dosages with dilutions of each tastant in 50% steps. The highest dosage could be easily detected (sucrose, 30 mg; citric acid, 3 mg; sodium chloride, 2 mg; caffeine, 2 mg), and the lowest concentration was within threshold range.

Twenty-eight tablets (six different dosages of the four basic tastes plus four tasteless tablets) were tried in a randomized order. The entire test required 15 to 20 minutes. To evaluate the within-subject test-retest reliability, sessions were repeated after 1 week. Results were compared with those obtained by means of a conventional three-drop, forced-choice procedure using the method of ascending limits.

Results of the new gustatory test were significantly correlated with those obtained using the three-drop, forced-choice procedure (correlation coefficient [r] = 0.66, P<.001). In general, women performed better than men. Furthermore, younger subjects exhibited a significantly higher gustatory sensitivity in both tests compared with older subjects.

This quantitative test of whole-mouth gustatory function is easy to use, can be self-administered, requires little time, and has a long shelf-life. It appears to be suited for routine clinical assessment of gustatory function.