The Test-Retest Reliability of Fatty Acid Taste Thresholds

Emerging evidence supports the existence of a fat specific oral detection system activated by fatty acids, which conveys the presence of fat in foods. Stability in psychophysical measurement of fatty acids is an essential step in supporting the existence of an oral fat detection system as well as supporting the association between fatty acid taste and development of obesity. This study aimed to determine the test-retest reliability of oral fatty acid thresholds. Seventeen subjects (eight males, age 31 +/- 2.3 years, BMI 22.9 +/- 0.6 kg/m(2), nine females, age 29 +/- 1.8 years, BMI 23.4 +/- 0.9 kg/m(2)) attended 30 laboratory sessions to determine oral detection thresholds for oleic acid (C18:1), linoleic acid (C18:2) and lauric acid (C12:0). Taste thresholds were also performed using sucrose (sweet), citric acid (sour), sodium chloride (salty), caffeine (bitter) and monosodium glutamate (umami). Each stimulus was evaluated on six occasions using ascending forced choice triangle tests, over 2 days. Diet records were also collected prior to each testing session. Fatty acid taste thresholds were determined for all subjects and strong intra-class correlations were found for within day and across day testing sessions for C18:1, C18:2 and C12:0. The strongest correlations were found for across day testing for C18:1 [intra-class correlation (ICC) = 0.78, confidence interval (CI) = 0.49-0.91], C18:2 (ICC = 0.94, CI = 0.84-0.98) and C12:0 (ICC = 0.80, CI = 0.54-0.92). Strong correlations were also found for sweet, sour, salty, bitter and umami tastes (ICC range, 0.7-0.9). This study provides evidence supportive of an oral fatty acid specific detection system.