Submitted on October 31, 2006
Accepted on January 25, 2007
Effects of linoleic acid on sweet, sour, salty and bitter taste thresholds and intensity ratings of adults
Richard D Mattes1*
1 Dept. of Foods and Nutrition, Purdue University, West Lafayette, Indiana, United States
* To whom correspondence should be addressed. E-mail: mattes{at}purdue.edu.
Evidence supporting a taste component for dietary fat has prompted study of plausible transduction mechanisms. One hypothesizes that long-chain, unsaturated fatty acids block selected delayed rectifying potassium channels resulting in a sensitization of taste receptor cells to stimulation by other taste compounds. This was tested in 17 male and 17 female adult. Participants were tested during two, 30 minute, test sessions per week for 8 weeks. Eight 5ml, room temperature, stimuli were assessed in random order via an ascending, three-alternative, forced-choice procedure. They included 1% solutions of linoleic acid with added NaCl, sucrose, citric acid, and caffeine as well as solutions of these taste compounds alone. Participants also rated the intensity of the five strongest concentrations using the general labeled magnitude scale. Ratings were made self-paced while wearing noseclips. It was hypothesized that taste thresholds would be lower and absolute intensity ratings or slopes of intensity functions would be higher for the stimuli mixed with the linoleic acid. Thresholds were compared by paired t-tests and intensity ratings by repeated measures analysis of variance. Thresholds were significantly higher (i.e., lower sensitivity) for the sodium chloride, citric acid and caffeine solutions with added fatty acid. Sweet, sour and salty intensity ratings were lower or unchanged by the addition of a fatty acid. The two highest concentrations of caffeine were rated as weaker in the presence of linoleic acid. These data do not support a mechanism for detecting dietary fats whereby fatty acids sensitize taste receptor cells to stimulation by taste compounds.
