Characterizing different-flavored e-cigarette solutions from user-reported sensory attributes and appeal.

Scientists and regulators need parsimonious methods of characterizing flavored e-cigarettes which may vary widely in both chemical flavoring constituents and marketing descriptors. This laboratory experiment characterized user-reported appeal and experience of five cross-cutting sensory attributes (sweetness, bitterness, smoothness, harshness, coolness) of 10 common e-cigarette flavors. In a within-subject double-blind single-visit protocol, current nicotine/tobacco product users (N = 119) self-administered a single puff of each e-liquid flavor via a pod-style device and rated its appeal and sensory attributes on 0-100 scales. Custom-manufactured e-liquids, nicotine concentration: M (SD) = 23.4 (0.9) mg/mL, representative of commonly marketed fruit (green apple, strawberry), dessert (dark chocolate, vanilla), mint (peppermint, spearmint), nonmint cooling (menthol, koolada), and tobacco (subtle tobacco, full-flavored tobacco) flavor descriptors were used and their constituents were independently analyzed. Results largely demonstrated that a flavor's sensory attributes concorded with its marketed flavor descriptor. Among the 10 flavors, vanilla was rated sweetest (B[difference vs. mean of 9 other flavors] = 14.44, 95% CI [10.84, 18.03]), full-flavored tobacco was most bitter, B = 8.34, 95% CI [4.73, 11.96], subtle tobacco was most harsh, B = 5.69, 95% CI [1.70, 9.68], and peppermint scored highest in both smoothness, B = 6.98, 95% CI [3.13, 10.82], and coolness, B = 29.25, 95% CI [25.50, 33.01]. Flavors with higher appeal ratings tended to be sweeter, smoother, cooler, and less bitter and harsh. Chemical analysis found numerous flavoring constituents among study products without any clear differentiation of chemicals being present in particular flavor categories, which underscores the utility of using sensory ratings to characterize different-flavored e-cigarettes over and above constituent analyses. Characterizing e-cigarette flavors by subjective sensory attributes may be useful in future research and regulatory activities. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Effect of Exposure to e-Cigarettes With Salt vs Free-Base Nicotine on the Appeal and Sensory Experience of Vaping: A Randomized Clinical Trial.

Importance: Alkaline free-base nicotine is bitter and a respiratory irritant. High-nicotine electronic cigarette (e-cigarette) products contain acid additives that change nicotine from a free-base to a protonated salt chemical form, which could improve the sensory experience of vaping, particularly among never smokers unaccustomed to inhaling free-base nicotine. Objective: To determine whether exposure to e-cigarettes with salt vs free-base nicotine formulations improves the appeal and sensory experience of vaping e-cigarettes and whether nicotine formulation effects differ by e-cigarette flavor and ever combustible cigarette smoking status. Design, Setting, and Participants: Single-visit double-blind within-participant randomized clinical trial was conducted in an academic medical center outpatient clinical research facility in Southern California. Participants were 119 individuals with past 30-day e-cigarette or combustible cigarette use aged 21 years or older recruited from November 2019 to March 2020. Interventions: Participants self-administered standardized puffs of each 10 differently flavored e-cigarette solutions using a pod-style device. Each flavor was administered in salt (benzoic acid added) and free-base (no benzoic acid) nicotine formulations with commensurate nicotine concentrations (mean, 23.6 mg/mL). The 20 solutions were administered in randomly assigned sequences. Immediately after puffing each solution, participants rated appeal and sensory attributes. Main Outcomes and Measures: Self-reported appeal (mean of like, dislike [reverse-scored], and willingness to use again ratings) and 4 sensory attributes (sweetness, smoothness, bitterness, and harshness; analyzed individually) on visual analog scales with not at all and extremely anchors (range, 0-100). Results: Of the 119 participants; 39 (32.8%) were female. The mean (SD) age was 42.1 (14.4) years; 105 (88.2%) were ever combustible cigarette smokers, and 66 (55.5%) were current e-cigarette users. Salt vs free-base nicotine formulations produced higher ratings of appeal (salt vs free-base mean difference effect estimate: b = 12.0; 95% CI, 9.9-14.1; P < .001), sweetness (b = 9.3; 95% CI, 7.1-11.4; P < .001), and smoothness (b = 17.4; 95% CI, 15.2-19.6; P < .001) and lower ratings of bitterness (b = -13.3; 95% CI, -15.4 to -11.2; P < .001) and harshness (b = -21.0; 95% CI, -23.2 to -18.7; P < .001). Nicotine formulation effects largely generalized across different flavors and the smoothness-enhancing and harshness-reducing effects of nicotine salt were stronger in never vs ever cigarette smokers. Conclusions and Relevance: In this randomized clinical trial of adult current nicotine or tobacco product users, controlled exposure to e-cigarette puffs with salt vs free-base nicotine formulations appeared to increase product appeal and improve the sensory experience of vaping, particularly among never smokers. Regulatory policies limiting acid additives in e-cigarettes might reduce the appeal of high-nicotine e-cigarettes among populations deterred from vaping e-cigarettes that emit harsh aerosol. Trial Registration: ClinicalTrials.gov Identifier: NCT04399031.

E-cigarette device power moderates the effects of non-tobacco flavors and nicotine on product appeal in young adults.

BACKGROUND: Identifying e-cigarette product characteristics that moderate the effects of non-tobacco flavors and nicotine on user appeal can inform regulations issued in tandem with e-cigarette nicotine and flavor policies aimed to protect young adult health. An e-cigarette device's electrical power affects the amount of solution aerosolized per puff, leading to more concentrated or diluted aerosol, which may alter product appeal. This laboratory experiment tested whether e-cigarette device power moderated the independent and interactive effects of non-tobacco flavors and nicotine on appeal in young adults. METHOD: In a within-subject design single-visit protocol, young adult e-cigarette users (N = 100) administered standardized doses of e-cigarette solutions varying in flavor (fruit, menthol, tobacco) and nicotine (nicotine-containing [6 mg/mL], nicotine-free). Solutions were administered via a variable-voltage tank-style device at low (7.3 W[3.3 V@1.5 Ω resistance]) and high (12.3 W[4.3 V@1.5 Ω resistance]) power settings. Participants rated each dose's appeal (0-100 scale). RESULTS: The high (vs. low) power setting attenuated the appeal-enhancing effects of menthol (vs. tobacco) flavors (Menthol × Power, estimate = -5.44, P = .03). Power did not moderate the appeal-enhancing effects of fruit flavors. High (vs. low) power amplified the appeal-reducing effects of nicotine-containing (vs. nicotine-free) solutions (Nicotine × Power, estimate = 6.69, P < .001) and augmented the extent to which fruit and menthol flavors suppressed nicotine's appeal-reducing effects (Flavor × Nicotine × Power, estimates = 9.40-14.85, Ps≤0.03). CONCLUSION: E-cigarette device power appears to moderate flavor- and nicotine-induced changes in product appeal in nuanced ways, including by augmenting the ability of non-tobacco flavors to mask nicotine's appeal-reducing effects. Regulatory restrictions on high-powered e-cigarette devices warrant consideration in efforts to protect young adult health.