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. © Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.