Oral examinations and whole-mouth taste tests using four tastes (sweet, salt, sour and bitter) solutions were conducted on the subjects.
The bitter solutions (0.05 m caffeine, 2.0 × 10−4 m SOA, 1.81 × 10− m quinine HCl, 6.0 × 10−4 m PROP) were tested in the following order: SOA, caffeine, quinine, PROP; PROP, quinine, caffeine, SOA.
After participants completed the tests with bitter solutions dissolved in water, they used the same scale to rate the taste intensity of a paper strip containing ∼1.2 mg of PROP that would dissolve in saliva upon being placed into the mouth.
Their taste descriptors for the 58 μg/ml orthosilicic acid solution were 'bitter sweet' or 'sweet'sweet
As expected CRS-exposed animals lost their preference for saccharin, but also failed to avoid a bitter quinine solution.
Directly following the last measurement for saccharin preference we changed to a 2-bottle preference test between water and mildly bitter quinine solution.
Bittern, very bitter-tasting solution that remains after evaporation and crystallization of sodium chloride (table salt) from brines and seawater.
Quinine, a bitter-tasting solution, is a punishment of the same sensory modality as a water reward.
To end the most bitter standoffs, perhaps the solution is as straightforward as getting each side to recognize the other's right to see the morning sun.
