PMC

2D t-SNE projection of the 300-D embeddings of 40 food ingredients, five from each of the eight food categories. (A) FlavorDB (B) FlavorGraph.

The figure shows flavor preference response patterns in the 5-class latent class analysis solution. All participants were asked, “How much do you like the following flavors for e-cigarettes or vapes?” for eight listed flavors (Fruit flavors; Candy or dessert flavors; Mint flavors; Icy, frost, or menthol flavors; Combined icy flavors, like “icy fruit”; Alcohol flavors; Tobacco flavor; Unflavored) with response options: strongly dislike; somewhat dislike; neither like or dislike; somewhat like; strongly like. The height of the unfilled bars shows the percent of the total sample that endorsed each option for each flavor. The height of the filled bars shows the percent of the members assigned to the specific class that endorsed each option for each flavor. For example, members of Class 1 were less likely than the total sample to endorse strongly dislike, somewhat dislike, and neither like or dislike for the flavor mint, while also being more likely than the total sample to endorse strongly like for mint.

FlavorDB is a seamless amalgamation of ‘entity space’ and ‘flavor space’. The resource provides a comprehensive dataset along with a user-friendly interface and interlinked search engines for exploring the flavor universe.

Effects of E-liquid ± high and low percent flavorings in BHI on planktonic bacterial growth. Each bar represents Mean ± SEM percent change from the planktonic growth in BHI control media (no E-liquids), n = 4 to 12 are the number of replicates. a = p < 0.05 from flavorless E-liquid, b = p < 0.01 from flavorless E-liquid and c = p < 0.001 from flavorless E-liquid.

(A). Pellet Mass before and after E-liquid or stock flavor treatments. The weight of oral streptococci pellets was determined before and after treatment with 100 µL of PBS, or 100 µL of flavorless E-liquid, or cinnamon or menthol stock flavorings. Each bar represents mean ± SEM (n = 3). ** p < 0.01, *** p < 0.001. (B). Pellet size of representative centrifuge tubes. Bacteria were exposed to 100 µL of PBS, flavorless E-liquid, or cinnamon and menthol flavoring agents for 15 min. Bacteria were then washed and pelleted. Green arrows indicate precipitation of menthol crystals and orange arrows indicate the presence of a hydrophobic material associated with the cinnamon flavor.

Flavoring composition of four popular flavored refill solutions. GCMS performed on flavored solutions identified notable overlap of flavoring chemicals present with three present in all four analyzed and an additional 16 present in two or more. Analysis also identified a wide range in the number of unique flavorings present from three in tobacco to 34 in menthol. See the for specific chemicals.

FlavorGraph. (A) Ingredient-ingredient relation. The relations between ingredients are shown; two ingredients are a “good pair” if they are used together in a large number of food recipes. The relations were obtained from Recipe1M. (B) Ingredient-compound relation. The relations between ingredients and chemical compounds are shown. These relations were obtained from FlavorDB and HyperFoods. (C) A partial view of FlavorGraph. Only 160 out of 6653 ingredients, 154 out of 1646 compounds, and their relations are shown in Fig. 1 for better illustration. Note that the whole graph was used for model training.

High-capacity real-time cellular analysis reveals toxicity thresholds of e-liquid flavorings. The toxicity thresholds of individual e-cigarette liquid flavoring constituents on 16HBE14o- cells was determined by cellular impedance changes over 24 h. a-d The highest concentration of each flavoring constituent was representative of the % v/v present in e-cigarette liquid. e-g The highest concentration of each flavoring constituent represented 1/10th the % v/v present in e-cigarette liquid. All flavors except furaneol (f) and vanillin (g) displayed cell index changes consistent with cytotoxicity that was validated with an MTS assay (h). *indicates significant difference from control cells and ^indicates significant difference between concentrations of the same flavoring, P < 0.05 in a one-way ANOVA with a Tukey’s Multiple Comparison Test

Verbal descriptions of odors in untrained subjects, trainee cooks, flavorists, and perfumers. (A) Whereas novice (untrained) subjects used more often sources and negative emotional terms to describe smells, experts used more technical terms when asked to verbalize about odors. (B) Novices used more emotional terms than trainee cooks, flavorists and perfumers and these terms are more often negatives. The number of chemical terms and olfactory qualities to describe odors is significantly higher in flavorists and perfumers than in novices and trainee cooks. Further, novices used less odor source references than trainee cooks, flavorists and perfumers and trainee cooks used less odor source references than flavorists and perfumers. *p < 0.05 (corrected for multiple comparisons).

Schematic of FlavorDB user interface highlighting features for searching and graphical navigation of data. (1) Flavor Molecule Search, (2) Entity/Ingredient Search, (3) Natural Source Search, (4) Flavor Pairing, (5) Advanced Search, (6) Molecular & Flavor Profile (including features for finding related entities, searching for structurally similar molecules, external link-outs and data download), (7) Molecule of the Day, (8) The Flavor Network and (9) Visual Search.

Kirby-Bauer assays depicting the effects of 100% concentrated flavorings in E-liquid on the Zone of Inhibition. Each bar represents mean ± SEM, n = 3 is the number of replicates. a = p < 0.05 from hydrogen peroxide (positive control) and b = p < 0.05 from negative control (flavorless E-liquid).

Product Appeal of e-Cigarettes with Fruit, Menthol, and Tobacco Flavored Solutions, by Power Setting (M±SE)
*Appeal rating significantly different between respective flavor condition and tobacco flavor condition at respective power setting (P < .001)
†Extent of difference in appeal between menthol and tobacco flavors significantly differs by power (Menthol × Power, P = .03).
Appeal = Average of “liking,” “willingness-to-use-again” and “disliking” (reverse-scored) (range 0-100).

Intake of flavored hydration gel during a 96-h choice test between two flavors; one that was previously available during shipping (or an equivalent period for controls; Paired) and the other that was novel (Unpaired). *p<0.05 relative to unpaired flavor. n = 24 per group.

Flavoring ingredients manually added to the mixing tank with a ventilated lid through an access port at a flavorings plant

The correlation between flavors and volatile flavor compounds. Correlation loadings plot of PLSR analysis between core volatile flavor compounds and flavors of CTLs (A). Co-occurrence networks of flavors and core volatile flavor compounds. Green line means negative correlation; red line means positive correlation (B).

Flavored solutions induced greater bronchodilation in newborn as compared to adult bronchial rings. Bronchial rings (BR) isolated from neonatal and adult ovine lung were treated with flavored solutions at 1:1000 dilution. (A) Menthol, strawberry, vanilla, and tobacco flavorings all induced bronchodilation of neonatal BR, while only menthol induced bronchodilation in adults (# p < 0.05 as compared to time control). Neonatal airway demonstrated significant decrease as compared to adult with both menthol and tobacco exposure (* p < 0.05 as compared to adult). Data are presented as mean + SEM. n = 3–8. (B) Representative tracing demonstrating neonatal and adult responses in BR treated with menthol flavoring (top) as compared to untreated (time control).

The flavors listed are based on products available on the market but is not a fully inclusive list.The flavors are organized in a new classification system. The inner circle is shaded based on the primary flavor category of the cigar. The outer circle correspond to the sub-category of flavors within the primary category.

FlavorGraph node representation results. (A) 2D t-SNE projection of whole food ingredient nodes (6653) and chemical compound nodes (flavor compounds: 1561, drug compounds: 84) from FlavorGraph. (B) <chemical hub ingredient-compound relation>. This figure shows the chemical compounds shared by wines and citrus fruits (orange, pineapple, grape, cranberry) and how they affect their overall taste. (C) <chemical hub ingredient-non hub ingredient>. This figure shows which common foods go well with certain wines and citrus fruits.

Chromatograms of PG/VG (vehicle control) and selected flavored e- liquids. A. PG/VG vehicle control chromatogram peaks were identified as PG (1.8 min) and VG (4.3 min). B. Apple Watermelon chromatogram flavoring agent peak was identified as triacetin (6.7 min). C. Strawberry Poptart chromatogram flavoring agent peaks were identified as triacetin (6.7 min), vanillin (7.2 min), and ethyl vanillin (7.6 min). D. Flamethrower chromatogram flavoring agent peak was identified as and trans-cinnamaldehyde (6.4 min).

Temporal graphs comparing trends of the volume of activity on r/JUUL related to flavors and strategies to evade flavored product restrictions as well as all activity on the subreddit. (Top) FTP policy workaround discussion (blue) as a portion of flavor discussion (orange) as a portion of all activity on the subreddit (gray). (Bottom) The all activity (gray) portion is removed to better visualize the variation in FTP policy workaround discussion (blue) as a portion of all flavor-related discussion (orange).