Influence of odor intensity and mood on hedonic reactions to aroma compounds in a multi-ethnic sample of young adults

This study was designed to investigate: 1) how nasal irritation influences the sensory perception of aromas; 2) the role of emotions in the preference and acceptance of aroma compounds; and 3) if ethnicity and genetic variation in taste sensitivity to the bitter compound 6-n-propylthiouracil (PROP) influence these outcomes. Ninety-six subjects (East Asian, n=53 and American Caucasians, n=43) were classified as PROP super-tasters; medium-tasters; and non-tasters. Subjects sniffed (orthonasally) aqueous solutions of cinnamaldehyde, methyl cinnamate, citral, citronellol, geraniol, and phenyl ethyl alcohol (PEA) at low (range =1-2.5 ppm) and mid-range (range =4-100ppm) concentrations in two separate sessions. Subjects rated intensity and overall liking for each aroma using 15-cm line scales. Pungency was rated for the mid-range concentrations only. Self-reported mood reactions to all aromas were collected using 8-point VAS scales. Additionally, subjects selected the most related mood descriptor of each aroma as an implicit measurement. Data were analyzed using ANOVA, multiple linear regression, and principal component analysis (PCA). Nasal pungency contributed to intensity perception, however, pungency and intensity did not influence aroma liking. Liking of cinnamaldehyde and citral increased with increasing concentration (p=0.05-0.003), but concentration did not influence liking of the other aromas. At mid-range concentration, East Asians liked cinnamaldehyde less than American Caucasians. PROP did not influence liking alone, however, East Asian subjects liked cinnamaldehyde less with increasing sensitivity to PROP, as expected. Positive mood (the mean of happy and excited VAS ratings) was associated with greater liking of most of the samples (p<0.002 for all). In multiple regression, positive mood predicted liking of cinnamaldehyde, methyl cinnamate, citral, and PEA at both concentrations (R2=0.27-0.45, p