Sensory attributes of e-cigarette flavours and nicotine as mediators of interproduct differences in appeal among young adults

Objective To estimate the extent to which specific sensory attributes, for example, smoothness, mediate differences in electronic cigarette (e-cigarette) appeal between products in non-tobacco versus tobacco flavours and varying nicotine content in young adults. Method E-cigarette users (n=100; aged 18–34 years) administered standardised two-puff e-cigarette doses of different products varying in a flavour (fruit, menthol, tobacco) × nicotine (nicotine-containing (6 mg/mL freebase), nicotine-free) within-subject design. Participants rated sensory attributes (sweetness, bitterness, smoothness and harshness) and appeal on 100-unit visual analogue scales after administering each product. Sensory ratings were tested as simultaneous mediators of flavour, nicotine and flavour × nicotine effects on appeal. Results Appeal preferences for fruit versus tobacco flavours were mediated by sweetness-enhancing (βindirect=0.092), smoothness-enhancing (βindirect=0.045) and bitterness-reducing (βindirect=0.072) effects of fruit flavours. Appeal preferences for menthol versus tobacco flavours were mediated by menthol’s smoothness-enhancing (βindirect=0.039) and bitterness-reducing (βindirect=0.034) effects. Lower appeal of nicotine-containing versus nicotine-free products was mediated by nicotine’s sweetness-reducing (βindirect=–0.036), smoothness-reducing (βindirect=–0.156) and bitterness-increasing (βindirect=0.045) effects. Flavour × nicotine interaction effects on appeal were explained by menthol-related suppression of nicotine’s bitterness-enhancing and sweetness-reducing mediation pathways and fruit-related suppression of nicotine’s bitterness-enhancing mediation pathway. Harshness did not mediate appeal after adjusting for other sensory attributes. Conclusion Bitterness and smoothness may be cross-cutting mediators of interproduct variation in the effects of types of non-tobacco flavours and nicotine on e-cigarette appeal in young adults. Sweetness may also mediate appeal-enhancing effects of fruit and appeal-reducing effects of nicotine. Non-tobacco flavours may suppress appeal-reducing effects of nicotine in e-cigarettes through attenuation of nicotine’s aversive taste attributes.