E-cigarette palatability in smokers as a function of flavorings, nicotine content and propylthiouracil (PROP) taster phenotype

Abstract

BackgroundThe popularity of E-cigarettes is due in part to their flavorings. The purpose of this study was to determine the effect on smokers' sensory perceptions and liking of various e-cigarette flavorings, and the degree to which those perceptions are influenced by nicotine level, sex, and PROP bitter taster phenotype. MethodsWe recruited 132 non-treatment-seeking, daily cigarette smokers. In repeated trials in one laboratory session participants vaped the Joyetech eGo-C e-cigarette with each of the following flavorings (in random order): unflavored, tobacco, cherry, chocolate, and menthol. Participants vaped the e-juice first without nicotine and then with high nicotine (18 mg/ml), and provided sensory (bitterness/sourness, irritation, sweetness) and liking ratings. Perceived intensity of 6-n-propylthiouracil (PROP) was used to classify the participants as non-tasters (n = 28), medium-tasters (n = 74), or supertasters (n = 28). Mixed-effects linear models and generalized estimating equations were used to evaluate ratings as a function of flavor interacting with nicotine content, sex and taster phenotype, adjusting for age, race/ethnicity, menthol use, and nicotine dependence. ResultsRegardless of nicotine level, cherry (β = 1.76, p < .001) and chocolate (β = 0.69, p < .001) were rated as sweeter, but were not better liked, than unflavored e-juice. Menthol elicited the highest liking rating, especially for women (β = 12.23, p < .05) and supertasters (β = 20.52, p < .05). Regardless of flavor, high nicotine was rated as more irritating (OR = 1.43, 95% CI = 1.02–2.01) than the no-nicotine e-juice. Irritation (β = −13.65, p < .001), bitterness/sourness (β = −11.38, p < .001), and sweetness (β = 4.79, p < .001) were associated with liking. ConclusionMenthol may enhance e-cigarette palatability for some smokers, which may increase e-cigarette utility in smoking cessation.